#  -*-cperl-*-
#  $Id$
#
#  Copyright (c) 2002-2008 Greg Sabino Mullane and others: see the Changes file
#  Portions Copyright (c) 2002 Jeffrey W. Baker
#  Portions Copyright (c) 1997-2001 Edmund Mergl
#  Portions Copyright (c) 1994-1997 Tim Bunce
#
#  You may distribute under the terms of either the GNU General Public
#  License or the Artistic License, as specified in the Perl README file.


use strict;
use warnings;
use 5.006001;

{
	package DBD::Pg;

	use version; our $VERSION = qv('2.9.0');

	use DBI ();
	use DynaLoader ();
	use Exporter ();
	use vars qw(@ISA %EXPORT_TAGS $err $errstr $sqlstate $drh $dbh $DBDPG_DEFAULT @EXPORT);
	@ISA = qw(DynaLoader Exporter);


	%EXPORT_TAGS =
		(
		 async => [qw(PG_ASYNC PG_OLDQUERY_CANCEL PG_OLDQUERY_WAIT)],
		 pg_types => [qw(
			PG_ABSTIME PG_ABSTIMEARRAY PG_ACLITEM PG_ACLITEMARRAY PG_ANY
			PG_ANYARRAY PG_ANYELEMENT PG_ANYENUM PG_ANYNONARRAY PG_BIT
			PG_BITARRAY PG_BOOL PG_BOOLARRAY PG_BOX PG_BOXARRAY
			PG_BPCHAR PG_BPCHARARRAY PG_BYTEA PG_BYTEAARRAY PG_CHAR
			PG_CHARARRAY PG_CID PG_CIDARRAY PG_CIDR PG_CIDRARRAY
			PG_CIRCLE PG_CIRCLEARRAY PG_CSTRING PG_CSTRINGARRAY PG_DATE
			PG_DATEARRAY PG_FLOAT4 PG_FLOAT4ARRAY PG_FLOAT8 PG_FLOAT8ARRAY
			PG_GTSVECTOR PG_GTSVECTORARRAY PG_INET PG_INETARRAY PG_INT2
			PG_INT2ARRAY PG_INT2VECTOR PG_INT2VECTORARRAY PG_INT4 PG_INT4ARRAY
			PG_INT8 PG_INT8ARRAY PG_INTERNAL PG_INTERVAL PG_INTERVALARRAY
			PG_LANGUAGE_HANDLER PG_LINE PG_LINEARRAY PG_LSEG PG_LSEGARRAY
			PG_MACADDR PG_MACADDRARRAY PG_MONEY PG_MONEYARRAY PG_NAME
			PG_NAMEARRAY PG_NUMERIC PG_NUMERICARRAY PG_OID PG_OIDARRAY
			PG_OIDVECTOR PG_OIDVECTORARRAY PG_OPAQUE PG_PATH PG_PATHARRAY
			PG_PG_ATTRIBUTE PG_PG_CLASS PG_PG_PROC PG_PG_TYPE PG_POINT
			PG_POINTARRAY PG_POLYGON PG_POLYGONARRAY PG_RECORD PG_REFCURSOR
			PG_REFCURSORARRAY PG_REGCLASS PG_REGCLASSARRAY PG_REGCONFIG PG_REGCONFIGARRAY
			PG_REGDICTIONARY PG_REGDICTIONARYARRAY PG_REGOPER PG_REGOPERARRAY PG_REGOPERATOR
			PG_REGOPERATORARRAY PG_REGPROC PG_REGPROCARRAY PG_REGPROCEDURE PG_REGPROCEDUREARRAY
			PG_REGTYPE PG_REGTYPEARRAY PG_RELTIME PG_RELTIMEARRAY PG_SMGR
			PG_TEXT PG_TEXTARRAY PG_TID PG_TIDARRAY PG_TIME
			PG_TIMEARRAY PG_TIMESTAMP PG_TIMESTAMPARRAY PG_TIMESTAMPTZ PG_TIMESTAMPTZARRAY
			PG_TIMETZ PG_TIMETZARRAY PG_TINTERVAL PG_TINTERVALARRAY PG_TRIGGER
			PG_TSQUERY PG_TSQUERYARRAY PG_TSVECTOR PG_TSVECTORARRAY PG_TXID_SNAPSHOT
			PG_TXID_SNAPSHOTARRAY PG_UNKNOWN PG_UUID PG_UUIDARRAY PG_VARBIT
			PG_VARBITARRAY PG_VARCHAR PG_VARCHARARRAY PG_VOID PG_XID
			PG_XIDARRAY PG_XML PG_XMLARRAY
		)]
	);

	{
		package DBD::Pg::DefaultValue;
		sub new { my $self = {}; return bless $self, shift; }
	}
	$DBDPG_DEFAULT = DBD::Pg::DefaultValue->new();
	Exporter::export_ok_tags('pg_types', 'async');
	@EXPORT = qw($DBDPG_DEFAULT PG_ASYNC PG_OLDQUERY_CANCEL PG_OLDQUERY_WAIT PG_BYTEA);

	require_version DBI 1.52;

	bootstrap DBD::Pg $VERSION;

	$err = 0;       # holds error code for DBI::err
	$errstr = '';   # holds error string for DBI::errstr
	$sqlstate = ''; # holds five character SQLSTATE code
	$drh = undef;   # holds driver handle once initialized

	## These two methods are here to allow calling before connect()
	sub parse_trace_flag {
		my ($class, $flag) = @_;
		return 0x01000000 if $flag eq 'pglibpq';
		return 0x02000000 if $flag eq 'pgstart';
		return 0x04000000 if $flag eq 'pgend';
		return 0x08000000 if $flag eq 'pgprefix';
		return 0x10000000 if $flag eq 'pglogin';
		return 0x20000000 if $flag eq 'pgquote';
		return DBI::parse_trace_flag($class, $flag);
	}
	sub parse_trace_flags {
		my ($class, $flags) = @_;
		return DBI::parse_trace_flags($class, $flags);
	}

	sub CLONE {
		$drh = undef;
		return;
	}

	## Deprecated
	sub _pg_use_catalog {
		return 'pg_catalog.';
	}

	sub driver {
		return $drh if defined $drh;
		my($class, $attr) = @_;

		$class .= '::dr';

		$drh = DBI::_new_drh($class, {
			'Name'        => 'Pg',
			'Version'     => $VERSION,
			'Err'         => \$DBD::Pg::err,
			'Errstr'      => \$DBD::Pg::errstr,
			'State'       => \$DBD::Pg::sqlstate,
			'Attribution' => "DBD::Pg $VERSION by Greg Sabino Mullane and others",
		});


		DBD::Pg::db->install_method('pg_cancel');
		DBD::Pg::db->install_method('pg_endcopy');
		DBD::Pg::db->install_method('pg_getline');
		DBD::Pg::db->install_method('pg_getcopydata');
		DBD::Pg::db->install_method('pg_getcopydata_async');
		DBD::Pg::db->install_method('pg_notifies');
		DBD::Pg::db->install_method('pg_putcopydata');
		DBD::Pg::db->install_method('pg_putcopyend');
		DBD::Pg::db->install_method('pg_ping');
		DBD::Pg::db->install_method('pg_putline');
		DBD::Pg::db->install_method('pg_ready');
		DBD::Pg::db->install_method('pg_release');
		DBD::Pg::db->install_method('pg_result');
		DBD::Pg::db->install_method('pg_rollback_to');
		DBD::Pg::db->install_method('pg_savepoint');
		DBD::Pg::db->install_method('pg_server_trace');
		DBD::Pg::db->install_method('pg_server_untrace');
		DBD::Pg::db->install_method('pg_type_info');

		DBD::Pg::st->install_method('pg_cancel');
		DBD::Pg::st->install_method('pg_result');
		DBD::Pg::st->install_method('pg_ready');

		return $drh;

	} ## end of driver


	1;

} ## end of package DBD::Pg


{
	package DBD::Pg::dr;

	use strict;

	## Returns an array of formatted database names from the pg_database table
	sub data_sources {

		my $drh = shift;
		my $attr = shift || '';
		## Future: connect to "postgres" when the minimum version we support is 8.0
		my $connstring = 'dbname=template1';
		if ($ENV{DBI_DSN}) {
			($connstring = $ENV{DBI_DSN}) =~ s/dbi:Pg://;
		}
		if (length $attr) {
			$connstring .= ";$attr";
		}

		my $dbh = DBD::Pg::dr::connect($drh, $connstring) or return undef;
		$dbh->{AutoCommit}=1;
		my $SQL = 'SELECT pg_catalog.quote_ident(datname) FROM pg_catalog.pg_database ORDER BY 1';
		my $sth = $dbh->prepare($SQL);
		$sth->execute() or die $DBI::errstr;
		$attr and $attr = ";$attr";
		my @sources = map { "dbi:Pg:dbname=$_->[0]$attr" } @{$sth->fetchall_arrayref()};
		$dbh->disconnect;
		return @sources;
	}


	sub connect { ## no critic (ProhibitBuiltinHomonyms)
		my ($drh, $dbname, $user, $pass)= @_;

		## Allow "db" and "database" as synonyms for "dbname"
		$dbname =~ s/\b(?:db|database)\s*=/dbname=/;

		my $name = $dbname;
		if ($dbname =~ m{dbname\s*=\s*[\"\']([^\"\']+)}) {
			$name = "'$1'";
			$dbname =~ s/\"/\'/g;
		}
		elsif ($dbname =~ m{dbname\s*=\s*([^;]+)}) {
			$name = $1;
		}

 		$user = defined($user) ? $user : defined $ENV{DBI_USER} ? $ENV{DBI_USER} : '';
		$pass = defined($pass) ? $pass : defined $ENV{DBI_PASS} ? $ENV{DBI_PASS} : '';

		my ($dbh) = DBI::_new_dbh($drh, {
			'Name'         => $dbname,
			'Username'     => $user,
			'CURRENT_USER' => $user,
		 });

		# Connect to the database..
		DBD::Pg::db::_login($dbh, $dbname, $user, $pass) or return undef;

		my $version = $dbh->{pg_server_version};
		$dbh->{private_dbdpg}{version} = $version;

		return $dbh;
	}

	sub private_attribute_info {
		return {
		};
	}

} ## end of package DBD::Pg::dr


{
	package DBD::Pg::db;

	use DBI qw(:sql_types);

	use strict;

	sub parse_trace_flag {
		my ($h, $flag) = @_;
		return DBD::Pg->parse_trace_flag($flag);
	}

	sub prepare {
		my($dbh, $statement, @attribs) = @_;

		return undef if ! defined $statement;

		# Create a 'blank' statement handle:
		my $sth = DBI::_new_sth($dbh, {
			'Statement' => $statement,
		});

		DBD::Pg::st::_prepare($sth, $statement, @attribs) || 0;

		return $sth;
	}

	sub last_insert_id {

		my ($dbh, $catalog, $schema, $table, $col, $attr) = @_;

		## Our ultimate goal is to get a sequence
		my ($sth, $count, $SQL, $sequence);

		## Cache all of our table lookups? Default is yes
		my $cache = 1;

		## Catalog and col are not used
		$schema = '' if ! defined $schema;
		$table = '' if ! defined $table;
		my $cachename = "lii$table$schema";

		if (defined $attr and length $attr) {
			## If not a hash, assume it is a sequence name
			if (! ref $attr) {
				$attr = {sequence => $attr};
			}
			elsif (ref $attr ne 'HASH') {
				$dbh->set_err(1, 'last_insert_id must be passed a hashref as the final argument');
				return undef;
			}
			## Named sequence overrides any table or schema settings
			if (exists $attr->{sequence} and length $attr->{sequence}) {
				$sequence = $attr->{sequence};
			}
			if (exists $attr->{pg_cache}) {
				$cache = $attr->{pg_cache};
			}
		}

		if (! defined $sequence and exists $dbh->{private_dbdpg}{$cachename} and $cache) {
			$sequence = $dbh->{private_dbdpg}{$cachename};
		}
		elsif (! defined $sequence) {
			## At this point, we must have a valid table name
			if (! length $table) {
				$dbh->set_err(1, 'last_insert_id needs at least a sequence or table name');
				return undef;
			}
			my @args = ($table);
			## Make sure the table in question exists and grab its oid
			my ($schemajoin,$schemawhere) = ('','');
			if (length $schema) {
				$schemajoin = "\n JOIN pg_catalog.pg_namespace n ON (n.oid = c.relnamespace)";
				$schemawhere = "\n AND n.nspname = ?";
				push @args, $schema;
			}
			$SQL = "SELECT c.oid FROM pg_catalog.pg_class c $schemajoin\n WHERE relname = ?$schemawhere";
			if (! length $schema) {
				$SQL .= ' AND pg_catalog.pg_table_is_visible(c.oid)';
			}
			$sth = $dbh->prepare_cached($SQL);
			$count = $sth->execute(@args);
			if (!defined $count or $count eq '0E0') {
				$sth->finish();
				my $message = qq{Could not find the table "$table"};
				length $schema and $message .= qq{ in the schema "$schema"};
				$dbh->set_err(1, $message);
				return undef;
			}
			my $oid = $sth->fetchall_arrayref()->[0][0];
			$oid =~ /(\d+)/ or die qq{OID was not numeric?!?\n};
			$oid = $1;
			## This table has a primary key. Is there a sequence associated with it via a unique, indexed column?
			$SQL = "SELECT a.attname, i.indisprimary, pg_catalog.pg_get_expr(adbin,adrelid)\n".
				"FROM pg_catalog.pg_index i, pg_catalog.pg_attribute a, pg_catalog.pg_attrdef d\n ".
				"WHERE i.indrelid = $oid AND d.adrelid=a.attrelid AND d.adnum=a.attnum\n".
				"  AND a.attrelid = $oid AND i.indisunique IS TRUE\n".
				"  AND a.atthasdef IS TRUE AND i.indkey[0]=a.attnum\n".
				q{ AND d.adsrc ~ '^nextval'};
			$sth = $dbh->prepare($SQL);
			$count = $sth->execute();
			if (!defined $count or $count eq '0E0') {
				$sth->finish();
				$dbh->set_err(1, qq{No suitable column found for last_insert_id of table "$table"});
				return undef;
			}
			my $info = $sth->fetchall_arrayref();

			## We have at least one with a default value. See if we can determine sequences
			my @def;
			for (@$info) {
				next unless $_->[2] =~ /^nextval\(+'([^']+)'::/o;
				push @$_, $1;
				push @def, $_;
			}
			if (!@def) {
				$dbh->set_err(1, qq{No suitable column found for last_insert_id of table "$table"\n});
			}
			## Tiebreaker goes to the primary keys
			if (@def > 1) {
				my @pri = grep { $_->[1] } @def;
				if (1 != @pri) {
					$dbh->set_err(1, qq{No suitable column found for last_insert_id of table "$table"\n});
				}
				@def = @pri;
			}
			$sequence = $def[0]->[3];
			## Cache this information for subsequent calls
			$dbh->{private_dbdpg}{$cachename} = $sequence;
		}

		$sth = $dbh->prepare_cached('SELECT currval(?)');
		$count = $sth->execute($sequence);
		return undef if ! defined $count;
		return $sth->fetchall_arrayref()->[0][0];

	} ## end of last_insert_id

	sub ping {
		my $dbh = shift;
		local $SIG{__WARN__} = sub { } if $dbh->FETCH('PrintError');
		my $ret = DBD::Pg::db::_ping($dbh);
		return $ret < 1 ? 0 : $ret;
	}

	sub pg_ping {
		my $dbh = shift;
		local $SIG{__WARN__} = sub { } if $dbh->FETCH('PrintError');
		return DBD::Pg::db::_ping($dbh);
	}

	sub pg_type_info {
		my($dbh,$pg_type) = @_;
		local $SIG{__WARN__} = sub { } if $dbh->FETCH('PrintError');
		my $ret = DBD::Pg::db::_pg_type_info($pg_type);
		return $ret;
	}

	# Column expected in statement handle returned.
	# table_cat, table_schem, table_name, column_name, data_type, type_name,
 	# column_size, buffer_length, DECIMAL_DIGITS, NUM_PREC_RADIX, NULLABLE,
	# REMARKS, COLUMN_DEF, SQL_DATA_TYPE, SQL_DATETIME_SUB, CHAR_OCTET_LENGTH,
	# ORDINAL_POSITION, IS_NULLABLE
	# The result set is ordered by TABLE_SCHEM, TABLE_NAME and ORDINAL_POSITION.

	sub column_info {
		my $dbh = shift;
		my ($catalog, $schema, $table, $column) = @_;

		my @search;
		## If the schema or table has an underscore or a %, use a LIKE comparison
		if (defined $schema and length $schema) {
			push @search, 'n.nspname ' . ($schema =~ /[_%]/ ? 'LIKE ' : '= ') .
				$dbh->quote($schema);
		}
		if (defined $table and length $table) {
			push @search, 'c.relname ' . ($table =~ /[_%]/ ? 'LIKE ' : '= ') .
				$dbh->quote($table);
		}
		if (defined $column and length $column) {
			push @search, 'a.attname ' . ($column =~ /[_%]/ ? 'LIKE ' : '= ') .
				$dbh->quote($column);
		}

		my $whereclause = join "\n\t\t\t\tAND ", '', @search;

		my $schemajoin = 'JOIN pg_catalog.pg_namespace n ON (n.oid = c.relnamespace)';

		my $remarks = 'pg_catalog.col_description(a.attrelid, a.attnum)';

		my $col_info_sql = qq!
			SELECT
				NULL::text AS "TABLE_CAT"
				, quote_ident(n.nspname) AS "TABLE_SCHEM"
				, quote_ident(c.relname) AS "TABLE_NAME"
				, quote_ident(a.attname) AS "COLUMN_NAME"
				, a.atttypid AS "DATA_TYPE"
				, pg_catalog.format_type(a.atttypid, NULL) AS "TYPE_NAME"
				, a.attlen AS "COLUMN_SIZE"
				, NULL::text AS "BUFFER_LENGTH"
				, NULL::text AS "DECIMAL_DIGITS"
				, NULL::text AS "NUM_PREC_RADIX"
				, CASE a.attnotnull WHEN 't' THEN 0 ELSE 1 END AS "NULLABLE"
				, $remarks AS "REMARKS"
				, af.adsrc AS "COLUMN_DEF"
				, NULL::text AS "SQL_DATA_TYPE"
				, NULL::text AS "SQL_DATETIME_SUB"
				, NULL::text AS "CHAR_OCTET_LENGTH"
				, a.attnum AS "ORDINAL_POSITION"
				, CASE a.attnotnull WHEN 't' THEN 'NO' ELSE 'YES' END AS "IS_NULLABLE"
				, pg_catalog.format_type(a.atttypid, a.atttypmod) AS "pg_type"
				, '?' AS "pg_constraint"
				, n.nspname AS "pg_schema"
				, c.relname AS "pg_table"
				, a.attname AS "pg_column"
				, a.attrelid AS "pg_attrelid"
				, a.attnum AS "pg_attnum"
				, a.atttypmod AS "pg_atttypmod"
				, t.typtype AS "_pg_type_typtype"
				, t.oid AS "_pg_type_oid"
			FROM
				pg_catalog.pg_type t
				JOIN pg_catalog.pg_attribute a ON (t.oid = a.atttypid)
				JOIN pg_catalog.pg_class c ON (a.attrelid = c.oid)
				LEFT JOIN pg_catalog.pg_attrdef af ON (a.attnum = af.adnum AND a.attrelid = af.adrelid)
				$schemajoin
			WHERE
				a.attnum >= 0
				AND c.relkind IN ('r','v')
				$whereclause
			ORDER BY "TABLE_SCHEM", "TABLE_NAME", "ORDINAL_POSITION"
			!;

		my $data = $dbh->selectall_arrayref($col_info_sql) or return undef;

		# To turn the data back into a statement handle, we need 
		# to fetch the data as an array of arrays, and also have a
		# a matching array of all the column names
		my %col_map = (qw/
			TABLE_CAT             0
			TABLE_SCHEM           1
			TABLE_NAME            2
			COLUMN_NAME           3
			DATA_TYPE             4
			TYPE_NAME             5
			COLUMN_SIZE           6
			BUFFER_LENGTH         7
			DECIMAL_DIGITS        8
			NUM_PREC_RADIX        9
			NULLABLE             10
			REMARKS              11
			COLUMN_DEF           12
			SQL_DATA_TYPE        13
			SQL_DATETIME_SUB     14
			CHAR_OCTET_LENGTH    15
			ORDINAL_POSITION     16
			IS_NULLABLE          17
			pg_type              18
			pg_constraint        19
			pg_schema            20
			pg_table             21
			pg_column            22
			pg_enum_values       23
			/);

		for my $row (@$data) {
			my $typoid = pop @$row;
			my $typtype = pop @$row;
			my $typmod = pop @$row;
			my $attnum = pop @$row;
			my $aid = pop @$row;

			$row->[$col_map{COLUMN_SIZE}] =
 				_calc_col_size($typmod,$row->[$col_map{COLUMN_SIZE}]);

			# Replace the Pg type with the SQL_ type
			$row->[$col_map{DATA_TYPE}] = DBD::Pg::db::pg_type_info($dbh,$row->[$col_map{DATA_TYPE}]);

			# Add pg_constraint
			my $SQL = q{SELECT consrc FROM pg_catalog.pg_constraint WHERE contype = 'c' AND }.
				qq{conrelid = $aid AND conkey = '{$attnum}'};
			my $info = $dbh->selectall_arrayref($SQL);
			if (@$info) {
				$row->[19] = $info->[0][0];
			}
			else {
				$row->[19] = undef;
			}

			if ( $typtype eq 'e' ) {
				my $SQL = "SELECT enumlabel FROM pg_catalog.pg_enum WHERE enumtypid = $typoid ORDER BY oid";
				$row->[23] = $dbh->selectcol_arrayref($SQL);
			}
			else {
				$row->[23] = undef;
			}
		}

		# Since we've processed the data in Perl, we have to jump through a hoop
		# To turn it back into a statement handle
		#
		return _prepare_from_data
			(
			 'column_info',
			 $data,
			 [ sort { $col_map{$a} <=> $col_map{$b} } keys %col_map]
			 );
	}

	sub _prepare_from_data {
		my ($statement, $data, $names, %attr) = @_;
		my $sponge = DBI->connect('dbi:Sponge:', '', '', { RaiseError => 1 });
		my $sth = $sponge->prepare($statement, { rows=>$data, NAME=>$names, %attr });
		return $sth;
	}

	sub statistics_info {

		my $dbh = shift;
		my ($catalog, $schema, $table, $unique_only, $quick, $attr) = @_;

		## Catalog is ignored, but table is mandatory
		return undef unless defined $table and length $table;

		my $schema_where = '';
		my @exe_args = ($table);

		my $input_schema = (defined $schema and length $schema) ? 1 : 0;

		if ($input_schema) {
			$schema_where = 'AND n.nspname = ? AND n.oid = d.relnamespace';
			push(@exe_args, $schema);
		}
		else {
			$schema_where = 'AND n.oid = d.relnamespace';
		}

		my $table_stats_sql = qq{
			SELECT d.relpages, d.reltuples, n.nspname
			FROM   pg_catalog.pg_class d, pg_catalog.pg_namespace n
			WHERE  d.relname = ? $schema_where
		};

		my $colnames_sql = qq{
			SELECT
				a.attnum, a.attname
			FROM
				pg_catalog.pg_attribute a, pg_catalog.pg_class d, pg_catalog.pg_namespace n
			WHERE
				a.attrelid = d.oid AND d.relname = ? $schema_where
		};

		my $stats_sql = qq{
			SELECT
				c.relname, i.indkey, i.indisunique, i.indisclustered, a.amname,
				n.nspname, c.relpages, c.reltuples, i.indexprs,
				pg_get_expr(i.indpred,i.indrelid) as predicate
			FROM
				pg_catalog.pg_index i, pg_catalog.pg_class c,
				pg_catalog.pg_class d, pg_catalog.pg_am a,
				pg_catalog.pg_namespace n
			WHERE
				d.relname = ? $schema_where AND d.oid = i.indrelid
				AND i.indexrelid = c.oid AND c.relam = a.oid
			ORDER BY
				i.indisunique desc, a.amname, c.relname
		};

		my @output_rows;

		# Table-level stats
		if (!$unique_only) {
			my $table_stats_sth = $dbh->prepare($table_stats_sql);
			$table_stats_sth->execute(@exe_args) or return undef;
			my $tst = $table_stats_sth->fetchrow_hashref or return undef;
			push(@output_rows, [
				undef,            # TABLE_CAT
				$tst->{nspname},  # TABLE_SCHEM
				$table,           # TABLE_NAME
				undef,            # NON_UNIQUE
				undef,            # INDEX_QUALIFIER
				undef,            # INDEX_NAME
				'table',          # TYPE
				undef,            # ORDINAL_POSITION
				undef,            # COLUMN_NAME
				undef,            # ASC_OR_DESC
				$tst->{reltuples},# CARDINALITY
				$tst->{relpages}, # PAGES
				undef,            # FILTER_CONDITION
			]);
		}

		# Fetch the column names for later use
		my $colnames_sth = $dbh->prepare($colnames_sql);
		$colnames_sth->execute(@exe_args) or return undef;
		my $colnames = $colnames_sth->fetchall_hashref('attnum');

		# Fetch the index definitions
		my $sth = $dbh->prepare($stats_sql);
		$sth->execute(@exe_args) or return undef;

		STAT_ROW:
		while (my $row = $sth->fetchrow_hashref) {
			next if $row->{indexprs}; # We can't return these accurately via this interface ...
			next if $unique_only and !$row->{indisunique};

			my $indtype = $row->{indisclustered}
				? 'clustered'
				: ( $row->{amname} eq 'btree' )
					? 'btree'
					: ($row->{amname} eq 'hash' )
						? 'hashed' : 'other';

			my $nonunique = $row->{indisunique} ? 0 : 1;

			my @index_row = (
				undef,             # TABLE_CAT
				$row->{nspname},   # TABLE_SCHEM
				$table,            # TABLE_NAME
				$nonunique,        # NON_UNIQUE
				undef,             # INDEX_QUALIFIER
				$row->{relname},   # INDEX_NAME
				$indtype,          # TYPE
				undef,             # ORDINAL_POSITION
				undef,             # COLUMN_NAME
				'A',               # ASC_OR_DESC
				$row->{reltuples}, # CARDINALITY
				$row->{relpages},  # PAGES
				$row->{predicate}, # FILTER_CONDITION
			);

			my $col_nums = $row->{indkey};
			$col_nums =~ s/^\s+//;
			my @col_nums = split(/\s+/, $col_nums);

			my $ord_pos = 1;
			for my $col_num (@col_nums) {
				my @copy = @index_row;
				$copy[7] = $ord_pos++; # ORDINAL_POSITION
				$copy[8] = $colnames->{$col_num}->{attname}; # COLUMN_NAME
				push(@output_rows, \@copy);
			}
		}

		my @output_colnames = qw/ TABLE_CAT TABLE_SCHEM TABLE_NAME NON_UNIQUE INDEX_QUALIFIER
					INDEX_NAME TYPE ORDINAL_POSITION COLUMN_NAME ASC_OR_DESC
					CARDINALITY PAGES FILTER_CONDITION /;

		return _prepare_from_data('statistics_info', \@output_rows, \@output_colnames);
	}

	sub primary_key_info {

		my $dbh = shift;
		my ($catalog, $schema, $table, $attr) = @_;

		## Catalog is ignored, but table is mandatory
		return undef unless defined $table and length $table;

		my $whereclause = 'AND c.relname = ' . $dbh->quote($table);

		if (defined $schema and length $schema) {
			$whereclause .= "\n\t\t\tAND n.nspname = " . $dbh->quote($schema);
		}

		my $TSJOIN = 'pg_catalog.pg_tablespace t ON (t.oid = c.reltablespace)';
		if ($dbh->{private_dbdpg}{version} < 80000) {
			$TSJOIN = '(SELECT 0 AS oid, 0 AS spcname, 0 AS spclocation LIMIT 0) AS t ON (t.oid=1)';
		}

		my $pri_key_sql = qq{
			SELECT
				  c.oid
				, quote_ident(n.nspname)
				, quote_ident(c.relname)
				, quote_ident(c2.relname)
				, i.indkey, quote_ident(t.spcname), quote_ident(t.spclocation)
				, n.nspname, c.relname, c2.relname
			FROM
				pg_catalog.pg_class c
				JOIN pg_catalog.pg_index i ON (i.indrelid = c.oid)
				JOIN pg_catalog.pg_class c2 ON (c2.oid = i.indexrelid)
				LEFT JOIN pg_catalog.pg_namespace n ON (n.oid = c.relnamespace)
				LEFT JOIN $TSJOIN
			WHERE
				i.indisprimary IS TRUE
			$whereclause
		};

		my $sth = $dbh->prepare($pri_key_sql) or return undef;
		$sth->execute();
		my $info = $sth->fetchall_arrayref()->[0];
		return undef if ! defined $info;

		# Get the attribute information
		my $indkey = join ',', split /\s+/, $info->[4];
		my $sql = qq{
			SELECT a.attnum, pg_catalog.quote_ident(a.attname) AS colname,
				pg_catalog.quote_ident(t.typname) AS typename
			FROM pg_catalog.pg_attribute a, pg_catalog.pg_type t
			WHERE a.attrelid = '$info->[0]'
			AND a.atttypid = t.oid
			AND attnum IN ($indkey);
		};
		$sth = $dbh->prepare($sql) or return undef;
		$sth->execute();
		my $attribs = $sth->fetchall_hashref('attnum');

		my $pkinfo = [];

		## Normal way: complete "row" per column in the primary key
		if (!exists $attr->{'pg_onerow'}) {
			my $x=0;
			my @key_seq = split/\s+/, $info->[4];
			for (@key_seq) {
				# TABLE_CAT
				$pkinfo->[$x][0] = undef;
				# SCHEMA_NAME
				$pkinfo->[$x][1] = $info->[1];
				# TABLE_NAME
				$pkinfo->[$x][2] = $info->[2];
				# COLUMN_NAME
				$pkinfo->[$x][3] = $attribs->{$_}{colname};
				# KEY_SEQ
				$pkinfo->[$x][4] = $_;
				# PK_NAME
				$pkinfo->[$x][5] = $info->[3];
				# DATA_TYPE
				$pkinfo->[$x][6] = $attribs->{$_}{typename};
				$pkinfo->[$x][7] = $info->[5];
				$pkinfo->[$x][8] = $info->[6];
				$pkinfo->[$x][9] = $info->[7];
				$pkinfo->[$x][10] = $info->[8];
				$pkinfo->[$x][11] = $info->[9];
				$x++;
			}
		}
		else { ## Nicer way: return only one row

			# TABLE_CAT
			$info->[0] = undef;
			# TABLESPACES
			$info->[7] = $info->[5];
			$info->[8] = $info->[6];
			# Unquoted names
			$info->[9] = $info->[7];
			$info->[10] = $info->[8];
			$info->[11] = $info->[9];
			# PK_NAME
			$info->[5] = $info->[3];
			# COLUMN_NAME
			$info->[3] = 2==$attr->{'pg_onerow'} ?
				[ map { $attribs->{$_}{colname} } split /\s+/, $info->[4] ] :
					join ', ', map { $attribs->{$_}{colname} } split /\s+/, $info->[4];
			# DATA_TYPE
			$info->[6] = 2==$attr->{'pg_onerow'} ?
				[ map { $attribs->{$_}{typename} } split /\s+/, $info->[4] ] :
					join ', ', map { $attribs->{$_}{typename} } split /\s+/, $info->[4];
			# KEY_SEQ
			$info->[4] = 2==$attr->{'pg_onerow'} ?
				[ split /\s+/, $info->[4] ] :
					join ', ', split /\s+/, $info->[4];

			$pkinfo = [$info];
		}

		my @cols = (qw(TABLE_CAT TABLE_SCHEM TABLE_NAME COLUMN_NAME
									 KEY_SEQ PK_NAME DATA_TYPE));
		push @cols, 'pg_tablespace_name', 'pg_tablespace_location';
		push @cols, 'pg_schema', 'pg_table', 'pg_column';

		return _prepare_from_data('primary_key_info', $pkinfo, \@cols);

	}

	sub primary_key {
		my $sth = primary_key_info(@_[0..3], {pg_onerow => 2});
		return defined $sth ? @{$sth->fetchall_arrayref()->[0][3]} : ();
	}


	sub foreign_key_info {

		my $dbh = shift;

		## PK: catalog, schema, table, FK: catalog, schema, table, attr

		## Each of these may be undef or empty
		my $pschema = $_[1] || '';
		my $ptable = $_[2] || '';
		my $fschema = $_[4] || '';
		my $ftable = $_[5] || '';
		my $args = $_[6];

		## No way to currently specify it, but we are ready when there is
		my $odbc = 0;

		## Must have at least one named table
		return undef if !$ptable and !$ftable;

		## If only the primary table is given, we return only those columns
		## that are used as foreign keys, even if that means that we return
		## unique keys but not primary one. We also return all the foreign
		## tables/columns that are referencing them, of course.

		## The first step is to find the oid of each specific table in the args:
		## Return undef if no matching relation found
		my %oid;
		for ([$ptable, $pschema, 'P'], [$ftable, $fschema, 'F']) {
			if (length $_->[0]) {
				my $SQL = "SELECT c.oid AS schema FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n\n".
					'WHERE c.relnamespace = n.oid AND c.relname = ' . $dbh->quote($_->[0]);
				if (length $_->[1]) {
					$SQL .= ' AND n.nspname = ' . $dbh->quote($_->[1]);
				}
				my $info = $dbh->selectall_arrayref($SQL);
				return undef if ! @$info;
				$oid{$_->[2]} = $info->[0][0];
			}
		}

		## We now need information about each constraint we care about.
		## Foreign table: only 'f' / Primary table: only 'p' or 'u'
		my $WHERE = $odbc ? q{((contype = 'p'} : q{((contype IN ('p','u')};
		if (length $ptable) {
			$WHERE .= " AND conrelid=$oid{'P'}::oid";
		}
		else {
			$WHERE .= " AND conrelid IN (SELECT DISTINCT confrelid FROM pg_catalog.pg_constraint WHERE conrelid=$oid{'F'}::oid)";
			if (length $pschema) {
				$WHERE .= ' AND n2.nspname = ' . $dbh->quote($pschema);
			}
		}

		$WHERE .= ")\n \t\t\t\tOR \n \t\t\t\t(contype = 'f'";
		if (length $ftable) {
			$WHERE .= " AND conrelid=$oid{'F'}::oid";
			if (length $ptable) {
				$WHERE .= " AND confrelid=$oid{'P'}::oid";
			}
		}
		else {
			$WHERE .= " AND confrelid = $oid{'P'}::oid";
			if (length $fschema) {
				$WHERE .= ' AND n2.nspname = ' . $dbh->quote($fschema);
			}
		}
		$WHERE .= '))';

		## Grab everything except specific column names:
		my $fk_sql = qq{
		SELECT conrelid, confrelid, contype, conkey, confkey,
			pg_catalog.quote_ident(c.relname) AS t_name, pg_catalog.quote_ident(n2.nspname) AS t_schema,
			pg_catalog.quote_ident(n.nspname) AS c_schema, pg_catalog.quote_ident(conname) AS c_name,
			CASE
				WHEN confupdtype = 'c' THEN 0
				WHEN confupdtype = 'r' THEN 1
				WHEN confupdtype = 'n' THEN 2
				WHEN confupdtype = 'a' THEN 3
				WHEN confupdtype = 'd' THEN 4
				ELSE -1
			END AS update,
			CASE
				WHEN confdeltype = 'c' THEN 0
				WHEN confdeltype = 'r' THEN 1
				WHEN confdeltype = 'n' THEN 2
				WHEN confdeltype = 'a' THEN 3
				WHEN confdeltype = 'd' THEN 4
				ELSE -1
			END AS delete,
			CASE
				WHEN condeferrable = 'f' THEN 7
				WHEN condeferred = 't' THEN 6
				WHEN condeferred = 'f' THEN 5
				ELSE -1
			END AS defer
			FROM pg_catalog.pg_constraint k, pg_catalog.pg_class c, pg_catalog.pg_namespace n, pg_catalog.pg_namespace n2
			WHERE $WHERE
				AND k.connamespace = n.oid
				AND k.conrelid = c.oid
				AND c.relnamespace = n2.oid
				ORDER BY conrelid ASC
				};

		my $sth = $dbh->prepare($fk_sql);
		$sth->execute();
		my $info = $sth->fetchall_arrayref({});
		return undef if ! defined $info or ! @$info;

		## Return undef if just ptable given but no fk found
		return undef if ! length $ftable and ! grep { $_->{'contype'} eq 'f'} @$info;

		## Figure out which columns we need information about
		my %colnum;
		for my $row (@$info) {
			for (@{$row->{'conkey'}}) {
				$colnum{$row->{'conrelid'}}{$_}++;
			}
			if ($row->{'contype'} eq 'f') {
				for (@{$row->{'confkey'}}) {
					$colnum{$row->{'confrelid'}}{$_}++;
				}
			}
		}
		## Get the information about the columns computed above
		my $SQL = qq{
			SELECT a.attrelid, a.attnum, pg_catalog.quote_ident(a.attname) AS colname, 
				pg_catalog.quote_ident(t.typname) AS typename
			FROM pg_catalog.pg_attribute a, pg_catalog.pg_type t
			WHERE a.atttypid = t.oid
			AND (\n};

		$SQL .= join "\n\t\t\t\tOR\n" => map {
			my $cols = join ',' => keys %{$colnum{$_}};
			"\t\t\t\t( a.attrelid = '$_' AND a.attnum IN ($cols) )"
		} sort keys %colnum;

		$sth = $dbh->prepare(qq{$SQL \)});
		$sth->execute();
		my $attribs = $sth->fetchall_arrayref({});

		## Make a lookup hash
		my %attinfo;
		for (@$attribs) {
			$attinfo{"$_->{'attrelid'}"}{"$_->{'attnum'}"} = $_;
		}

		## This is an array in case we have identical oid/column combos. Lowest oid wins
		my %ukey;
		for my $c (grep { $_->{'contype'} ne 'f' } @$info) {
			## Munge multi-column keys into sequential order
			my $multi = join ' ' => sort @{$c->{'conkey'}};
			push @{$ukey{$c->{'conrelid'}}{$multi}}, $c;
		}

		## Finally, return as a SQL/CLI structure:
		my $fkinfo = [];
		my $x=0;
		for my $t (sort { $a->{'c_name'} cmp $b->{'c_name'} } grep { $_->{'contype'} eq 'f' } @$info) {
			## We need to find which constraint row (if any) matches our confrelid-confkey combo
			## by checking out ukey hash. We sort for proper matching of { 1 2 } vs. { 2 1 }
			## No match means we have a pure index constraint
			my $u;
			my $multi = join ' ' => sort @{$t->{'confkey'}};
			if (exists $ukey{$t->{'confrelid'}}{$multi}) {
				$u = $ukey{$t->{'confrelid'}}{$multi}->[0];
			}
			else {
				## Mark this as an index so we can fudge things later on
				$multi = 'index';
				## Grab the first one found, modify later on as needed
				$u = ((values %{$ukey{$t->{'confrelid'}}})[0]||[])->[0];
				## Bail in case there was no match
				next if ! ref $u;
			}

			## ODBC is primary keys only
			next if $odbc and ($u->{'contype'} ne 'p' or $multi eq 'index');

			my $conkey = $t->{'conkey'};
			my $confkey = $t->{'confkey'};
			for (my $y=0; $conkey->[$y]; $y++) {
				# UK_TABLE_CAT
				$fkinfo->[$x][0] = undef;
				# UK_TABLE_SCHEM
				$fkinfo->[$x][1] = $u->{'t_schema'};
				# UK_TABLE_NAME
				$fkinfo->[$x][2] = $u->{'t_name'};
				# UK_COLUMN_NAME
				$fkinfo->[$x][3] = $attinfo{$t->{'confrelid'}}{$confkey->[$y]}{'colname'};
				# FK_TABLE_CAT
				$fkinfo->[$x][4] = undef;
				# FK_TABLE_SCHEM
				$fkinfo->[$x][5] = $t->{'t_schema'};
				# FK_TABLE_NAME
				$fkinfo->[$x][6] = $t->{'t_name'};
				# FK_COLUMN_NAME
				$fkinfo->[$x][7] = $attinfo{$t->{'conrelid'}}{$conkey->[$y]}{'colname'};
				# ORDINAL_POSITION
				$fkinfo->[$x][8] = $conkey->[$y];
				# UPDATE_RULE
				$fkinfo->[$x][9] = "$t->{'update'}";
				# DELETE_RULE
				$fkinfo->[$x][10] = "$t->{'delete'}";
				# FK_NAME
				$fkinfo->[$x][11] = $t->{'c_name'};
				# UK_NAME (may be undef if an index with no named constraint)
				$fkinfo->[$x][12] = $multi eq 'index' ? undef : $u->{'c_name'};
				# DEFERRABILITY
				$fkinfo->[$x][13] = "$t->{'defer'}";
				# UNIQUE_OR_PRIMARY
				$fkinfo->[$x][14] = ($u->{'contype'} eq 'p' and $multi ne 'index') ? 'PRIMARY' : 'UNIQUE';
				# UK_DATA_TYPE
				$fkinfo->[$x][15] = $attinfo{$t->{'confrelid'}}{$confkey->[$y]}{'typename'};
				# FK_DATA_TYPE
				$fkinfo->[$x][16] = $attinfo{$t->{'conrelid'}}{$conkey->[$y]}{'typename'};
				$x++;
			} ## End each column in this foreign key
		} ## End each foreign key

		my @CLI_cols = (qw(
			UK_TABLE_CAT UK_TABLE_SCHEM UK_TABLE_NAME UK_COLUMN_NAME
			FK_TABLE_CAT FK_TABLE_SCHEM FK_TABLE_NAME FK_COLUMN_NAME
			ORDINAL_POSITION UPDATE_RULE DELETE_RULE FK_NAME UK_NAME
			DEFERABILITY UNIQUE_OR_PRIMARY UK_DATA_TYPE FK_DATA_TYPE
		));

		my @ODBC_cols = (qw(
			PKTABLE_CAT PKTABLE_SCHEM PKTABLE_NAME PKCOLUMN_NAME
			FKTABLE_CAT FKTABLE_SCHEM FKTABLE_NAME FKCOLUMN_NAME
			KEY_SEQ UPDATE_RULE DELETE_RULE FK_NAME PK_NAME
			DEFERABILITY UNIQUE_OR_PRIMARY PK_DATA_TYPE FKDATA_TYPE
		));
		return _prepare_from_data('foreign_key_info', $fkinfo, $odbc ? \@ODBC_cols : \@CLI_cols);

	}


	sub table_info {

		my $dbh = shift;
		my ($catalog, $schema, $table, $type) = @_;

		my $tbl_sql = ();

		my $extracols = q{,NULL::text AS pg_schema, NULL::text AS pg_table};
		if ( # Rule 19a
				(defined $catalog and $catalog eq '%')
				and (defined $schema and $schema eq '')
				and (defined $table and $table eq '')
			 ) {
			$tbl_sql = qq{
					SELECT
						 NULL::text AS "TABLE_CAT"
					 , NULL::text AS "TABLE_SCHEM"
					 , NULL::text AS "TABLE_NAME"
					 , NULL::text AS "TABLE_TYPE"
					 , NULL::text AS "REMARKS" $extracols
					};
		}
		elsif (# Rule 19b
					 (defined $catalog and $catalog eq '')
					 and (defined $schema and $schema eq '%')
					 and (defined $table and $table eq '')
					) {
			$extracols = q{,n.nspname AS pg_schema, NULL::text AS pg_table};
			$tbl_sql = qq{SELECT
						 NULL::text AS "TABLE_CAT"
					 , quote_ident(n.nspname) AS "TABLE_SCHEM"
					 , NULL::text AS "TABLE_NAME"
					 , NULL::text AS "TABLE_TYPE"
					 , CASE WHEN n.nspname ~ '^pg_' THEN 'system schema' ELSE 'owned by ' || pg_get_userbyid(n.nspowner) END AS "REMARKS" $extracols
					FROM pg_catalog.pg_namespace n
					ORDER BY "TABLE_SCHEM"
					};
		}
		elsif (# Rule 19c
					 (defined $catalog and $catalog eq '')
					 and (defined $schema and $schema eq '')
					 and (defined $table and $table eq '')
					 and (defined $type and $type eq '%')
					) {
			$tbl_sql = qq{
					SELECT
					   NULL::text AS "TABLE_CAT"
					 , NULL::text AS "TABLE_SCHEM"
					 , NULL::text AS "TABLE_NAME"
					 , 'TABLE'    AS "TABLE_TYPE"
					 , 'relkind: r' AS "REMARKS" $extracols
					UNION
					SELECT
					   NULL::text AS "TABLE_CAT"
					 , NULL::text AS "TABLE_SCHEM"
					 , NULL::text AS "TABLE_NAME"
					 , 'VIEW'     AS "TABLE_TYPE"
					 , 'relkind: v' AS "REMARKS" $extracols
				};
		}
		else {
			# Default SQL
			$extracols = q{,n.nspname AS pg_schema, c.relname AS pg_table};
			my @search;
			my $showtablespace = ', quote_ident(t.spcname) AS "pg_tablespace_name", quote_ident(t.spclocation) AS "pg_tablespace_location"';

			## If the schema or table has an underscore or a %, use a LIKE comparison
			if (defined $schema and length $schema) {
					push @search, 'n.nspname ' . ($schema =~ /[_%]/ ? 'LIKE ' : '= ') . $dbh->quote($schema);
			}
			if (defined $table and length $table) {
					push @search, 'c.relname ' . ($table =~ /[_%]/ ? 'LIKE ' : '= ') . $dbh->quote($table);
			}
			## All we can see is "table" or "view". Default is both
			my $typesearch = q{IN ('r','v')};
			if (defined $type and length $type) {
				if ($type =~ /\btable\b/i and $type !~ /\bview\b/i) {
					$typesearch = q{= 'r'};
				}
				elsif ($type =~ /\bview\b/i and $type !~ /\btable\b/i) {
					$typesearch = q{= 'v'};
				}
			}
			push @search, "c.relkind $typesearch";

			my $TSJOIN = 'pg_catalog.pg_tablespace t ON (t.oid = c.reltablespace)';
			if ($dbh->{private_dbdpg}{version} < 80000) {
				$TSJOIN = '(SELECT 0 AS oid, 0 AS spcname, 0 AS spclocation LIMIT 0) AS t ON (t.oid=1)';
			}
			my $whereclause = join "\n\t\t\t\t\t AND " => @search;
			$tbl_sql = qq{
				SELECT NULL::text AS "TABLE_CAT"
					 , quote_ident(n.nspname) AS "TABLE_SCHEM"
					 , quote_ident(c.relname) AS "TABLE_NAME"
					 , CASE
					 		WHEN c.relkind = 'v' THEN
								CASE WHEN quote_ident(n.nspname) ~ '^pg_' THEN 'SYSTEM VIEW' ELSE 'VIEW' END
							ELSE
								CASE WHEN quote_ident(n.nspname) ~ '^pg_' THEN 'SYSTEM TABLE' ELSE 'TABLE' END
						END AS "TABLE_TYPE"
					 , d.description AS "REMARKS" $showtablespace $extracols
				FROM pg_catalog.pg_class AS c
					LEFT JOIN pg_catalog.pg_description AS d
						ON (c.oid = d.objoid AND c.tableoid = d.classoid AND d.objsubid = 0)
					LEFT JOIN pg_catalog.pg_namespace n ON (n.oid = c.relnamespace)
					LEFT JOIN $TSJOIN
				WHERE $whereclause
				ORDER BY "TABLE_TYPE", "TABLE_CAT", "TABLE_SCHEM", "TABLE_NAME"
				};
		}
		my $sth = $dbh->prepare( $tbl_sql ) or return undef;
		$sth->execute();

		return $sth;
	}

	sub tables {
			my ($dbh, @args) = @_;
			my $attr = $args[4];
			my $sth = $dbh->table_info(@args) or return;
			my $tables = $sth->fetchall_arrayref() or return;
			my @tables = map { (! (ref $attr eq 'HASH' and $attr->{pg_noprefix})) ?
						"$_->[1].$_->[2]" : $_->[2] } @$tables;
			return @tables;
	}

	sub table_attributes {
		my ($dbh, $table) = @_;

		my $sth = $dbh->column_info(undef,undef,$table,undef);

		my %convert = (
			COLUMN_NAME   => 'NAME',
			DATA_TYPE     => 'TYPE',
			COLUMN_SIZE   => 'SIZE',
			NULLABLE      => 'NOTNULL',
			REMARKS       => 'REMARKS',
			COLUMN_DEF    => 'DEFAULT',
			pg_constraint => 'CONSTRAINT',
		);

		my $attrs = $sth->fetchall_arrayref(\%convert);

		for my $row (@$attrs) {
			# switch the column names
			for my $name (keys %$row) {
				$row->{ $convert{$name} } = $row->{$name};

				## Keep some original columns
				delete $row->{$name} unless ($name eq 'REMARKS' or $name eq 'NULLABLE');

			}
			# Moved check outside of loop as it was inverting the NOTNULL value for
			# attribute.
			# NOTNULL inverts the sense of NULLABLE
			$row->{NOTNULL} = ($row->{NOTNULL} ? 0 : 1);

			my @pri_keys = ();
			@pri_keys = $dbh->primary_key( undef, undef, $table );
			$row->{PRIMARY_KEY} = scalar(grep { /^$row->{NAME}$/i } @pri_keys) ? 1 : 0;
		}

		return $attrs;

	}

	sub _calc_col_size {

		my $mod = shift;
		my $size = shift;


		if ((defined $size) and ($size > 0)) {
			return $size;
		} elsif ($mod > 0xffff) {
			my $prec = ($mod & 0xffff) - 4;
			$mod >>= 16;
			my $dig = $mod;
			return "$prec,$dig";
		} elsif ($mod >= 4) {
			return $mod - 4;
		} # else {
			# $rtn = $mod;
			# $rtn = undef;
		# }

		return;
	}


	sub type_info_all {
		my ($dbh) = @_;

		my $names =
			{
			 TYPE_NAME          => 0,
			 DATA_TYPE          => 1,
			 COLUMN_SIZE        => 2,
			 LITERAL_PREFIX     => 3,
			 LITERAL_SUFFIX     => 4,
			 CREATE_PARAMS      => 5,
			 NULLABLE           => 6,
			 CASE_SENSITIVE     => 7,
			 SEARCHABLE         => 8,
			 UNSIGNED_ATTRIBUTE => 9,
			 FIXED_PREC_SCALE   => 10,
			 AUTO_UNIQUE_VALUE  => 11,
			 LOCAL_TYPE_NAME    => 12,
			 MINIMUM_SCALE      => 13,
			 MAXIMUM_SCALE      => 14,
			 SQL_DATA_TYPE      => 15,
			 SQL_DATETIME_SUB   => 16,
			 NUM_PREC_RADIX     => 17,
			 INTERVAL_PRECISION => 18,
			};

		## This list is derived from dbi_sql.h in DBI, from types.c and types.h, and from the PG docs

		## Aids to make the list more readable:
		my $GIG = 1073741824;
		my $PS = 'precision/scale';
		my $LEN = 'length';
		my $UN = undef;
		my $ti =
			[
			 $names,
# name     sql_type          size   pfx/sfx crt   n/c/s    +-/P/I   local       min max  sub rdx itvl

['unknown',  SQL_UNKNOWN_TYPE,  0,    $UN,$UN,   $UN,  1,0,0, $UN,0,0, 'UNKNOWN',   $UN,$UN,
             SQL_UNKNOWN_TYPE,                                                             $UN, $UN, $UN ],
['bytea',    SQL_VARBINARY,     $GIG, q{'},q{'}, $UN,  1,0,3, $UN,0,0, 'BYTEA',     $UN,$UN,
             SQL_VARBINARY,                                                                $UN, $UN, $UN ],
['bpchar',   SQL_CHAR,          $GIG, q{'},q{'}, $LEN, 1,1,3, $UN,0,0, 'CHARACTER', $UN,$UN,
             SQL_CHAR,                                                                     $UN, $UN, $UN ],
['numeric',  SQL_DECIMAL,       1000, $UN,$UN,   $PS,  1,0,2, 0,0,0,   'FLOAT',     0,1000,
             SQL_DECIMAL,                                                                  $UN, $UN, $UN ],
['numeric',  SQL_NUMERIC,       1000, $UN,$UN,   $PS,  1,0,2, 0,0,0,   'FLOAT',     0,1000,
             SQL_NUMERIC,                                                                  $UN, $UN, $UN ],
['int4',     SQL_INTEGER,       10,   $UN,$UN,   $UN,  1,0,2, 0,0,0,   'INTEGER',   0,0,
             SQL_INTEGER,                                                                  $UN, $UN, $UN ],
['int2',     SQL_SMALLINT,      5,    $UN,$UN,   $UN,  1,0,2, 0,0,0,   'SMALLINT',  0,0,
             SQL_SMALLINT,                                                                 $UN, $UN, $UN ],
['float4',   SQL_FLOAT,         6,    $UN,$UN,   $PS,  1,0,2, 0,0,0,   'FLOAT',     0,6,
             SQL_FLOAT,                                                                    $UN, $UN, $UN ],
['float8',   SQL_REAL,          15,   $UN,$UN,   $PS,  1,0,2, 0,0,0,   'REAL',      0,15,
             SQL_REAL,                                                                     $UN, $UN, $UN ],
['int8',     SQL_DOUBLE,        20,   $UN,$UN,   $UN,  1,0,2, 0,0,0,   'LONGINT',   0,0,
             SQL_DOUBLE,                                                                   $UN, $UN, $UN ],
['date',     SQL_DATE,          10,   q{'},q{'}, $UN,  1,0,2, $UN,0,0, 'DATE',      0,0,
             SQL_DATE,                                                                     $UN, $UN, $UN ],
['tinterval',SQL_TIME,          18,   q{'},q{'}, $UN,  1,0,2, $UN,0,0, 'TINTERVAL', 0,6,
             SQL_TIME,                                                                     $UN, $UN, $UN ],
['timestamp',SQL_TIMESTAMP,     29,   q{'},q{'}, $UN,  1,0,2, $UN,0,0, 'TIMESTAMP', 0,6,
             SQL_TIMESTAMP,                                                                $UN, $UN, $UN ],
['text',     SQL_VARCHAR,       $GIG, q{'},q{'}, $LEN, 1,1,3, $UN,0,0, 'TEXT',      $UN,$UN,
             SQL_VARCHAR,                                                                  $UN, $UN, $UN ],
['bool',     SQL_BOOLEAN,       1,    q{'},q{'}, $UN,  1,0,2, $UN,0,0, 'BOOLEAN',   $UN,$UN,
             SQL_BOOLEAN,                                                                  $UN, $UN, $UN ],
['array',    SQL_ARRAY,         1,    q{'},q{'}, $UN,  1,0,2, $UN,0,0, 'ARRAY',     $UN,$UN,
             SQL_ARRAY,                                                                    $UN, $UN, $UN ],
['date',     SQL_TYPE_DATE,     10,   q{'},q{'}, $UN,  1,0,2, $UN,0,0, 'DATE',      0,0,
             SQL_TYPE_DATE,                                                                $UN, $UN, $UN ],
['time',     SQL_TYPE_TIME,     18,   q{'},q{'}, $UN,  1,0,2, $UN,0,0, 'TIME',      0,6,
             SQL_TYPE_TIME,                                                                $UN, $UN, $UN ],
['timestamp',SQL_TYPE_TIMESTAMP,29,   q{'},q{'}, $UN,  1,0,2, $UN,0,0, 'TIMESTAMP', 0,6,
             SQL_TYPE_TIMESTAMP,                                                           $UN, $UN, $UN ],
['timetz',   SQL_TYPE_TIME_WITH_TIMEZONE,
                                29,   q{'},q{'}, $UN,  1,0,2, $UN,0,0, 'TIMETZ',    0,6,
             SQL_TYPE_TIME_WITH_TIMEZONE,                                                  $UN, $UN, $UN ],
['timestamptz',SQL_TYPE_TIMESTAMP_WITH_TIMEZONE,
                                29,   q{'},q{'}, $UN,  1,0,2, $UN,0,0, 'TIMESTAMPTZ',0,6,
             SQL_TYPE_TIMESTAMP_WITH_TIMEZONE,                                             $UN, $UN, $UN ],
		#
		# intentionally omitted: char, all geometric types, internal types
	];
	return $ti;
	}


	# Characters that need to be escaped by quote().
	my %esc = (
		q{'}  => '\\047', # '\\' . sprintf("%03o", ord("'")), # ISO SQL 2
		'\\' => '\\134', # '\\' . sprintf("%03o", ord("\\")),
	);

	# Set up lookup for SQL types we don't want to escape.
	my %no_escape = map { $_ => 1 }
		DBI::SQL_INTEGER, DBI::SQL_SMALLINT, DBI::SQL_DECIMAL,
		DBI::SQL_FLOAT, DBI::SQL_REAL, DBI::SQL_DOUBLE, DBI::SQL_NUMERIC;

	sub get_info {

		my ($dbh,$type) = @_;

		return undef unless defined $type and length $type;

		my %type = (

## Driver information:

     116 => ['SQL_ACTIVE_ENVIRONMENTS',             0                         ], ## unlimited
   10021 => ['SQL_ASYNC_MODE',                      2                         ], ## SQL_AM_STATEMENT
     120 => ['SQL_BATCH_ROW_COUNT',                 2                         ], ## SQL_BRC_EXPLICIT
     121 => ['SQL_BATCH_SUPPORT',                   3                         ], ## 12 SELECT_PROC + ROW_COUNT_PROC
       2 => ['SQL_DATA_SOURCE_NAME',                "dbi:Pg:$dbh->{Name}"     ],
       3 => ['SQL_DRIVER_HDBC',                     0                         ], ## not applicable
     135 => ['SQL_DRIVER_HDESC',                    0                         ], ## not applicable
       4 => ['SQL_DRIVER_HENV',                     0                         ], ## not applicable
      76 => ['SQL_DRIVER_HLIB',                     0                         ], ## not applicable
       5 => ['SQL_DRIVER_HSTMT',                    0                         ], ## not applicable
	   ## Not clear what should go here. Some things suggest 'Pg', others 'Pg.pm'. We'll use DBD::Pg for now
       6 => ['SQL_DRIVER_NAME',                     'DBD::Pg'                 ],
      77 => ['SQL_DRIVER_ODBC_VERSION',             '03.00'                   ],
       7 => ['SQL_DRIVER_VER',                      'DBDVERSION'              ], ## magic word
     144 => ['SQL_DYNAMIC_CURSOR_ATTRIBUTES1',      0                         ], ## we can FETCH, but not via methods
     145 => ['SQL_DYNAMIC_CURSOR_ATTRIBUTES2',      0                         ], ## same as above
      84 => ['SQL_FILE_USAGE',                      0                         ], ## SQL_FILE_NOT_SUPPORTED (this is good)
     146 => ['SQL_FORWARD_ONLY_CURSOR_ATTRIBUTES1', 519                       ], ## not clear what this refers to in DBD context
     147 => ['SQL_FORWARD_ONLY_CURSOR_ATTRIBUTES2', 5209                      ], ## see above
      81 => ['SQL_GETDATA_EXTENSIONS',              15                        ], ## 1+2+4+8
     149 => ['SQL_INFO_SCHEMA_VIEWS',               3932149                   ], ## not: assert, charset, collat, trans
     150 => ['SQL_KEYSET_CURSOR_ATTRIBUTES1',       0                         ], ## applies to us?
     151 => ['SQL_KEYSET_CURSOR_ATTRIBUTES2',       0                         ], ## see above
   10022 => ['SQL_MAX_ASYNC_CONCURRENT_STATEMENTS', 0                         ], ## unlimited, probably
       0 => ['SQL_MAX_DRIVER_CONNECTIONS',          'MAXCONNECTIONS'          ], ## magic word
     152 => ['SQL_ODBC_INTERFACE_CONFORMANCE',      1                         ], ## SQL_OIC_LEVEL_1
      10 => ['SQL_ODBC_VER',                        '03.00.0000'              ],
     153 => ['SQL_PARAM_ARRAY_ROW_COUNTS',          2                         ], ## correct?
     154 => ['SQL_PARAM_ARRAY_SELECTS',             3                         ], ## PAS_NO_SELECT
      11 => ['SQL_ROW_UPDATES',                     'N'                       ],
      14 => ['SQL_SEARCH_PATTERN_ESCAPE',           '\\'                      ],
      13 => ['SQL_SERVER_NAME',                     'CURRENTDB'               ], ## magic word
     166 => ['SQL_STANDARD_CLI_CONFORMANCE',        2                         ], ## ??
     167 => ['SQL_STATIC_CURSOR_ATTRIBUTES1',       519                       ], ## ??
     168 => ['SQL_STATIC_CURSOR_ATTRIBUTES2',       5209                      ], ## ??

## DBMS Information

      16 => ['SQL_DATABASE_NAME',                   'CURRENTDB'               ], ## magic word
      17 => ['SQL_DBMS_NAME',                       'PostgreSQL'              ],
      18 => ['SQL_DBMS_VERSION',                    'ODBCVERSION'             ], ## magic word

## Data source information

      20 => ['SQL_ACCESSIBLE_PROCEDURES',           'Y'                       ], ## is this really true?
      19 => ['SQL_ACCESSIBLE_TABLES',               'Y'                       ], ## is this really true?
      82 => ['SQL_BOOKMARK_PERSISTENCE',            0                         ],
      42 => ['SQL_CATALOG_TERM',                    ''                        ], ## empty = catalogs are not supported
   10004 => ['SQL_COLLATION_SEQ',                   'ENCODING'                ], ## magic word
      22 => ['SQL_CONCAT_NULL_BEHAVIOR',            0                         ], ## SQL_CB_NULL
      23 => ['SQL_CURSOR_COMMIT_BEHAVIOR',          1                         ], ## SQL_CB_CLOSE
      24 => ['SQL_CURSOR_ROLLBACK_BEHAVIOR',        1                         ], ## SQL_CB_CLOSE
   10001 => ['SQL_CURSOR_SENSITIVITY',              1                         ], ## SQL_INSENSITIVE
      25 => ['SQL_DATA_SOURCE_READ_ONLY',           'READONLY'                ], ## magic word
      26 => ['SQL_DEFAULT_TXN_ISOLATION',           'DEFAULTTXN'              ], ## magic word (2 or 8)
   10002 => ['SQL_DESCRIBE_PARAMETER',              'Y'                       ],
      36 => ['SQL_MULT_RESULT_SETS',                'Y'                       ],
      37 => ['SQL_MULTIPLE_ACTIVE_TXN',             'Y'                       ],
     111 => ['SQL_NEED_LONG_DATA_LEN',              'N'                       ],
      85 => ['SQL_NULL_COLLATION',                  0                         ], ## SQL_NC_HIGH
      40 => ['SQL_PROCEDURE_TERM',                  'function'                ], ## for now
      39 => ['SQL_SCHEMA_TERM',                     'schema'                  ],
      44 => ['SQL_SCROLL_OPTIONS',                  8                         ], ## not really for DBD?
      45 => ['SQL_TABLE_TERM',                      'table'                   ],
      46 => ['SQL_TXN_CAPABLE',                     2                         ], ## SQL_TC_ALL
      72 => ['SQL_TXN_ISOLATION_OPTION',            10                        ], ## 2+8
      47 => ['SQL_USER_NAME',                       $dbh->{CURRENT_USER}      ],

## Supported SQL

     169  => ['SQL_AGGREGATE_FUNCTIONS',            127                       ], ## all of 'em
     117  => ['SQL_ALTER_DOMAIN',                   31                        ], ## all but deferred
      86  => ['SQL_ALTER_TABLE',                    32639                     ], ## no collate
     114  => ['SQL_CATALOG_LOCATION',               0                         ],
   10003  => ['SQL_CATALOG_NAME',                   'N'                       ],
      41  => ['SQL_CATALOG_NAME_SEPARATOR',         ''                        ],
      92  => ['SQL_CATALOG_USAGE',                  0                         ],
      87  => ['SQL_COLUMN_ALIAS',                   'Y'                       ],
      74  => ['SQL_CORRELATION_NAME',               2                         ], ## SQL_CN_ANY
     127  => ['SQL_CREATE_ASSERTION',               0                         ],
     128  => ['SQL_CREATE_CHARACTER_SET',           0                         ],
     129  => ['SQL_CREATE_COLLATION',               0                         ],
     130  => ['SQL_CREATE_DOMAIN',                  23                        ], ## no collation, no defer
     131  => ['SQL_CREATE_SCHEMA',                  3                         ], ## 1+2 schema + authorize
     132  => ['SQL_CREATE_TABLE',                   13845                     ], ## no collation
     133  => ['SQL_CREATE_TRANSLATION',             0                         ],
     134  => ['SQL_CREATE_VIEW',                    9                         ], ## local + create?
     119  => ['SQL_DATETIME_LITERALS',              65535                     ], ## all?
     170  => ['SQL_DDL_INDEX',                      3                         ], ## create + drop
     136  => ['SQL_DROP_ASSERTION',                 0                         ],
     137  => ['SQL_DROP_CHARACTER_SET',             0                         ],
     138  => ['SQL_DROP_COLLATION',                 0                         ],
     139  => ['SQL_DROP_DOMAIN',                    7                         ],
     140  => ['SQL_DROP_SCHEMA',                    7                         ],
     141  => ['SQL_DROP_TABLE',                     7                         ],
     142  => ['SQL_DROP_TRANSLATION',               0                         ],
     143  => ['SQL_DROP_VIEW',                      7                         ],
      27  => ['SQL_EXPRESSIONS_IN_ORDERBY',         'Y'                       ],
      88  => ['SQL_GROUP_BY',                       2                         ], ## GROUP_BY_CONTAINS_SELECT
      28  => ['SQL_IDENTIFIER_CASE',                2                         ], ## SQL_IC_LOWER
      29  => ['SQL_IDENTIFIER_QUOTE_CHAR',          q{"}                      ],
     148  => ['SQL_INDEX_KEYWORDS',                 0                         ], ## not needed for Pg
     172  => ['SQL_INSERT_STATEMENT',               7                         ], ## 1+2+4 = all
      73  => ['SQL_INTEGERITY',                     'Y'                       ], ## e.g. ON DELETE CASCADE?
      89  => ['SQL_KEYWORDS',                       'KEYWORDS'                ], ## magic word
     113  => ['SQL_LIKE_ESCAPE_CLAUSE',             'Y'                       ],
      75  => ['SQL_NON_NULLABLE_COLUMNS',           1                         ], ## NNC_NOT_NULL
     115  => ['SQL_OJ_CAPABILITIES',                127                       ], ## all
      90  => ['SQL_ORDER_BY_COLUMNS_IN_SELECT',     'N'                       ],
      38  => ['SQL_OUTER_JOINS',                    'Y'                       ],
      21  => ['SQL_PROCEDURES',                     'Y'                       ],
      93  => ['SQL_QUOTED_IDENTIFIER_CASE',         3                         ], ## SQL_IC_SENSITIVE
      91  => ['SQL_SCHEMA_USAGE',                   31                        ], ## all
      94  => ['SQL_SPECIAL_CHARACTERS',             '$'                       ], ## there are actually many more...
     118  => ['SQL_SQL_CONFORMANCE',                4                         ], ## SQL92_INTERMEDIATE ??
      95  => ['SQL_SUBQUERIES',                     31                        ], ## all
      96  => ['SQL_UNION',                          3                         ], ## 1+2 = all

## SQL limits

     112  => ['SQL_MAX_BINARY_LITERAL_LEN',         0                         ],
      34  => ['SQL_MAX_CATALOG_NAME_LEN',           0                         ],
     108  => ['SQL_MAX_CHAR_LITERAL_LEN',           0                         ],
      30  => ['SQL_MAX_COLUMN_NAME_LEN',            'NAMEDATALEN'             ], ## magic word
      97  => ['SQL_MAX_COLUMNS_IN_GROUP_BY',        0                         ],
      98  => ['SQL_MAX_COLUMNS_IN_INDEX',           0                         ],
      99  => ['SQL_MAX_COLUMNS_IN_ORDER_BY',        0                         ],
     100  => ['SQL_MAX_COLUMNS_IN_SELECT',          0                         ],
     101  => ['SQL_MAX_COLUMNS_IN_TABLE',           250                       ], ## 250-1600 (depends on column types)
      31  => ['SQL_MAX_CURSOR_NAME_LEN',            'NAMEDATALEN'             ], ## magic word
   10005  => ['SQL_MAX_IDENTIFIER_LEN',             'NAMEDATALEN'             ], ## magic word
     102  => ['SQL_MAX_INDEX_SIZE',                 0                         ],
     102  => ['SQL_MAX_PROCEDURE_NAME_LEN',         'NAMEDATALEN'             ], ## magic word
     104  => ['SQL_MAX_ROW_SIZE',                   0                         ], ## actually 1.6 TB, but too big to represent here
     103  => ['SQL_MAX_ROW_SIZE_INCLUDES_LONG',     'Y'                       ],
      32  => ['SQL_MAX_SCHEMA_NAME_LEN',            'NAMEDATALEN'             ], ## magic word
     105  => ['SQL_MAX_STATEMENT_LEN',              0                         ],
      35  => ['SQL_MAX_TABLE_NAME_LEN',             'NAMEDATALEN'             ], ## magic word
     106  => ['SQL_MAX_TABLES_IN_SELECT',           0                         ],
     107  => ['SQL_MAX_USER_NAME_LEN',              'NAMEDATALEN'             ], ## magic word

## Scalar function information

      48  => ['SQL_CONVERT_FUNCTIONS',              2                         ], ## CVT_CAST only?
      49  => ['SQL_NUMERIC_FUNCTIONS',              16777215                  ], ## ?? all but some naming clashes: rand(om), trunc(ate), log10=ln, etc.
      50  => ['SQL_STRING_FUNCTIONS',               16280984                  ], ## ??
      51  => ['SQL_SYSTEM_FUNCTIONS',               0                         ], ## ??
     109  => ['SQL_TIMEDATE_ADD_INTERVALS',         0                         ], ## ?? no explicit timestampadd?
     110  => ['SQL_TIMEDATE_DIFF_INTERVALS',        0                         ], ## ??
      52  => ['SQL_TIMEDATE_FUNCTIONS',             1966083                   ],

## Conversion information - all but BIT, LONGVARBINARY, and LONGVARCHAR

      53  => ['SQL_CONVERT_BIGINT',                 1830399                    ],
      54  => ['SQL_CONVERT_BINARY',                 1830399                    ],
      55  => ['SQL_CONVERT_BIT',                    0                          ],
      56  => ['SQL_CONVERT_CHAR',                   1830399                    ],
      57  => ['SQL_CONVERT_DATE',                   1830399                    ],
      58  => ['SQL_CONVERT_DECIMAL',                1830399                    ],
      59  => ['SQL_CONVERT_DOUBLE',                 1830399                    ],
      60  => ['SQL_CONVERT_FLOAT',                  1830399                    ],
      61  => ['SQL_CONVERT_INTEGER',                1830399                    ],
     123  => ['SQL_CONVERT_INTERVAL_DAY_TIME',      1830399                    ],
     124  => ['SQL_CONVERT_INTERVAL_YEAR_MONTH',    1830399                    ],
      71  => ['SQL_CONVERT_LONGVARBINARY',          0                          ],
      62  => ['SQL_CONVERT_LONGVARCHAR',            0                          ],
      63  => ['SQL_CONVERT_NUMERIC',                1830399                    ],
      64  => ['SQL_CONVERT_REAL',                   1830399                    ],
      65  => ['SQL_CONVERT_SMALLINT',               1830399                    ],
      66  => ['SQL_CONVERT_TIME',                   1830399                    ],
      67  => ['SQL_CONVERT_TIMESTAMP',              1830399                    ],
      68  => ['SQL_CONVERT_TINYINT',                1830399                    ],
      69  => ['SQL_CONVERT_VARBINARY',              0                          ],
      70  => ['SQL_CONVERT_VARCHAR',                1830399                    ],
     122  => ['SQL_CONVERT_WCHAR',                  0                          ],
     125  => ['SQL_CONVERT_WLONGVARCHAR',           0                          ],
     126  => ['SQL_CONVERT_WVARCHAR',               0                          ],

		); ## end of %type

		## Put both numbers and names into a hash
		my %t;
		for (keys %type) {
			$t{$_} = $type{$_}->[1];
			$t{$type{$_}->[0]} = $type{$_}->[1];
		}

		return undef unless exists $t{$type};

		my $ans = $t{$type};

		if ($ans eq 'NAMEDATALEN') {
			return $dbh->selectall_arrayref('SHOW max_identifier_length')->[0][0];
		}
		elsif ($ans eq 'ODBCVERSION') {
			my $version = $dbh->{private_dbdpg}{version};
			return '00.00.0000' unless $version =~ /^(\d\d?)(\d\d)(\d\d)$/o;
			return sprintf '%02d.%02d.%.2d00', $1,$2,$3;
		}
		elsif ($ans eq 'DBDVERSION') {
			my $simpleversion = $DBD::Pg::VERSION;
			$simpleversion =~ s/_/./g;
			return sprintf '%02d.%02d.%1d%1d%1d%1d', split (/\./, "$simpleversion.0.0.0.0.0.0");
		}
		 elsif ($ans eq 'MAXCONNECTIONS') {
			 return $dbh->selectall_arrayref('SHOW max_connections')->[0][0];
		 }
		 elsif ($ans eq 'ENCODING') {
			 return $dbh->selectall_arrayref('SHOW server_encoding')->[0][0];
		 }
		 elsif ($ans eq 'KEYWORDS') {
			## http://www.postgresql.org/docs/current/static/sql-keywords-appendix.html
			## Basically, we want ones that are 'reserved' for PostgreSQL but not 'reserved' in SQL:2003
			## 
			return join ',' => (qw(ANALYSE ANALYZE ASC DEFERRABLE DESC DO FREEZE ILIKE INITIALLY ISNULL LIMIT NOTNULL OFF OFFSET PLACING RETURNING VERBOSE));
		 }
		 elsif ($ans eq 'CURRENTDB') {
			 return $dbh->selectall_arrayref('SELECT pg_catalog.current_database()')->[0][0];
		 }
		 elsif ($ans eq 'READONLY') {
			 my $SQL = q{SELECT CASE WHEN setting = 'on' THEN 'Y' ELSE 'N' END FROM pg_settings WHERE name = 'transaction_read_only'};
			 my $info = $dbh->selectall_arrayref($SQL);
			 return defined $info->[0] ? $info->[0][0] : 'N';
		 }
		 elsif ($ans eq 'DEFAULTTXN') {
			 my $SQL = q{SELECT CASE WHEN setting = 'read committed' THEN 2 ELSE 8 END FROM pg_settings WHERE name = 'default_transaction_isolation'};
			 my $info = $dbh->selectall_arrayref($SQL);
			 return defined $info->[0] ? $info->[0][0] : 2;
		 }

		 return $ans;
	} # end of get_info

	sub private_attribute_info {
		return {
				pg_async_status                => undef,
				pg_bool_tf                     => undef,
				pg_db                          => undef,
				pg_default_port                => undef,
				pg_enable_utf8                 => undef,
				pg_errorlevel                  => undef,
				pg_expand_array                => undef,
				pg_host                        => undef,
				pg_INV_READ                    => undef,
				pg_INV_WRITE                   => undef,
				pg_lib_version                 => undef,
				pg_options                     => undef,
				pg_pass                        => undef,
				pg_pid                         => undef,
				pg_placeholder_dollaronly      => undef,
				pg_port                        => undef,
				pg_prepare_now                 => undef,
				pg_protocol                    => undef,
				pg_server_prepare              => undef,
				pg_server_version              => undef,
				pg_socket                      => undef,
				pg_standard_conforming_strings => undef,
				pg_user                        => undef,
		};
	}
}


{
	package DBD::Pg::st;

	sub parse_trace_flag {
		my ($h, $flag) = @_;
		return DBD::Pg->parse_trace_flag($flag);
	}

	sub bind_param_array {

		## The DBI version is broken, so we implement a near-copy here
		my $sth = shift;
		my ($p_id, $value_array, $attr) = @_;

		return $sth->set_err(1, "Value for parameter $p_id must be a scalar or an arrayref, not a ".ref($value_array))
			if defined $value_array and ref $value_array and ref $value_array ne 'ARRAY';

		return $sth->set_err(1, q{Can't use named placeholders for non-driver supported bind_param_array})
			unless DBI::looks_like_number($p_id); # because we rely on execute(@ary) here

		# get/create arrayref to hold params
		my $hash_of_arrays = $sth->{ParamArrays} ||= { };

		if (ref $value_array eq 'ARRAY') {
			# check that input has same length as existing
			# find first arrayref entry (if any)
			for (keys %$hash_of_arrays) {
				my $v = $$hash_of_arrays{$_};
				next unless ref $v eq 'ARRAY';
				return $sth->set_err
					(1,"Arrayref for parameter $p_id has ".@$value_array.' elements'
					 ." but parameter $_ has ".@$v)
					if @$value_array != @$v;
			}
		}

		$$hash_of_arrays{$p_id} = $value_array;
		return $sth->bind_param($p_id, '', $attr) if $attr; ## This is the big change so -w does not complain
		return 1;
	} ## end bind_param_array

	sub private_attribute_info {
		return {
				pg_async                  => undef,
				pg_bound                  => undef,
				pg_current_row            => undef,
				pg_direct                 => undef,
				pg_numbound               => undef,
				pg_cmd_status             => undef,
				pg_oid_status             => undef,
				pg_placeholder_dollaronly => undef,
				pg_prepare_name           => undef,
				pg_prepare_now            => undef,
				pg_segments               => undef,
				pg_server_prepare         => undef,
				pg_size                   => undef,
				pg_type                   => undef,
		};
    }

} ## end st section

1;

__END__

=head1 NAME

DBD::Pg - PostgreSQL database driver for the DBI module

=head1 SYNOPSIS

  use DBI;

  $dbh = DBI->connect("dbi:Pg:dbname=$dbname", '', '', {AutoCommit => 0});
  # The AutoCommit attribute should always be explicitly set

  # For some advanced uses you may need PostgreSQL type values:
  use DBD::Pg qw(:pg_types);

  # For asynchronous calls, import the async constants:
  use DBD::Pg qw(:async);

  $dbh->do('INSERT INTO mytable(a) VALUES (1)');

  $sth = $dbh->prepare('INSERT INTO mytable(a) VALUES (?)');
  $sth->execute();

=head1 VERSION

This documents version 2.9.0 of the DBD::Pg module

=head1 DESCRIPTION

DBD::Pg is a Perl module that works with the DBI module to provide access to
PostgreSQL databases.

=head1 MODULE DOCUMENTATION

This documentation describes driver specific behavior and restrictions. It is
not supposed to be used as the only reference for the user. In any case
consult the B<DBI> documentation first!

=for html <a href="http://search.cpan.org/~timb/DBI/DBI.pm">Latest DBI docmentation.</a>

=head1 THE DBI CLASS

=head2 DBI Class Methods

=head3 B<connect>

This method creates a database handle by connecting to a database, and is the DBI 
equivalent of the "new" method. To connect to a Postgres database with a minimum of parameters, 
use the following syntax:

  $dbh = DBI->connect("dbi:Pg:dbname=$dbname", '', '', {AutoCommit => 0});

This connects to the database named in the C<$dbname> variable on the default port (usually 5432) 
without any user authentication.

The following connect statement shows almost all possible parameters:

  $dbh = DBI->connect("dbi:Pg:dbname=$dbname;host=$host;port=$port;options=$options",
                      $username,
                      $password,
                      {AutoCommit => 0, RaiseError => 1, PrintError => 0}
                     );

If a parameter is not given, the connect() method will first look for 
specific environment variables, and then fall back to hard-coded defaults:

  parameter    environment variable    hard coded default
  ------------------------------------------------------
  host         PGHOST                  local domain socket
  hostaddr     PGHOSTADDR              local domain socket
  port         PGPORT                  5432
  dbname*      PGDATABASE              current userid
  username     PGUSER                  current userid
  password     PGPASSWORD              (none)
  options      PGOPTIONS               (none)
  service      PGSERVICE               (none)
  sslmode      PGSSLMODE               (none)

* May also use the aliases C<db> or C<database>

If the username and password values passed via C<connect()> are undefined (as opposed 
to merely being empty strings), DBI will use the environment variables I<DBI_USER> 
and I<DBI_PASS> if they exist.

You can also connect by using a service connection file, which is named 
F<pg_service.conf>. The location of this file can be controlled by 
setting the I<PGSYSCONFDIR> environment variable. To use one of the named 
services within the file, set the name by using either the I<service> parameter 
or the environment variable I<PGSERVICE>. Note that when connecting this way, 
only the minimum parameters should be used. For example, to connect to a 
service named "zephyr", you could use:

  $dbh = DBI->connect("dbi:Pg:service=zephyr", '', '');

You could also set C<$ENV{PGSERVICE}> to "zephyr" and connect like this:

  $dbh = DBI->connect("dbi:Pg:", '', '');

The format of the F<pg_service.conf> file is simply a bracketed service 
name, followed by one parameter per line in the format name=value.
For example:

  [zephyr]
  dbname=winds
  user=wisp
  password=W$2Hc00YSgP
  port=6543

There are four valid arguments to the I<sslmode> parameter, which controls 
whether to use SSL to connect to the database:

=over 4

=item * disable: SSL connections are never used

=item * allow: try non-SSL, then SSL

=item * prefer: try SSL, then non-SSL

=item * require: connect only with SSL

=back

You can also connect using sockets in a specific directory. This 
may be needed if the server you are connecting to has a different 
default socket directory from the one used to compile DBD::Pg. 
Use the complete path to the socket directory as the name of the 
host, like this:

  $dbh = DBI->connect('dbi:Pg:dbname=foo;host=/var/tmp/socket',
    $username,
    $password,
    {AutoCommit => 0, RaiseError => 1});

=head3 B<connect_cached>

  $dbh = DBI->connect_cached("dbi:Pg:dbname=$dbname", $username, $password, \%options);

Implemented by DBI, no driver-specific impact.

=head3 B<data_sources>

  @data_sources = DBI->data_sources('Pg');
  @data_sources = $dbh->data_sources();

Returns a list of available databases. Unless the environment variable C<DBI_DSN> is set, 
a connection will be attempted to the database C<template1>. The normal connection 
environment variables also apply, such as C<PGHOST>, C<PGPORT>, C<DBI_USER>, 
C<DBI_PASS>, and C<PGSERVICE>.

You can also pass in options to add to the connection string For example, to specify 
an alternate port and host:

  @data_sources = DBI->data_sources('Pg', 'port=5824;host=example.com');

  or:

  @data_sources = $dbh->data_sources('port=5824;host=example.com');


=head2 Methods Common To All Handles

For all of the methods below, B<$h> can be either a database handle (B<$dbh>) 
or a statement handle (B<$sth>). Note that I<$dbh> and I<$sth> can be replaced with 
any variable name you choose: these are just the names most often used. Another 
common variable used in this documentation is $I<rv>, which stands for "return value".

=head3 B<err>

  $rv = $h->err;

Returns the error code from the last method called. For the connect method it returns
C<PQstatus>, which is a number used by I<libpq> (the Postgres connection library). A value of 0 
indicates no error (CONNECTION_OK), while any other number indicates a failed connection. The 
only other number commonly seen is 1 (CONNECTION_BAD). See the libpq documentation for the 
complete list of return codes.

In all other non-connect methods C<$h->err> returns the C<PQresultStatus> of the current
handle. This is a number used by libpq and is one of:

  0  Empty query string
  1  A command that returns no data successfully completed.
  2  A command that returns data sucessfully completed.
  3  A COPY OUT command is still in progress.
  4  A COPY IN command is still in progress.
  5  A bad response was received from the backend.
  6  A nonfatal error occurred (a notice or warning message)
  7  A fatal error was returned: the last query failed.

=head3 B<errstr>

  $str = $h->errstr;

Returns the last error that was reported by Postgres. This message is affected 
by the L</pg_errorlevel> setting.

=head3 B<state>

  $str = $h->state;

Returns a five-character "SQLSTATE" code. Success is indicated by a C<00000> code, which 
gets mapped to an empty string by DBI. A code of C<S8006> indicates a connection failure, 
usually because the connection to the Postgres server has been lost.

While this method can be called as either C<$sth->state> or C<$dbh->state>, it 
is usually clearer to always use C<$dbh->state>.

The list of codes used by PostgreSQL can be found at:
L<http://www.postgresql.org/docs/current/static/errcodes-appendix.html>

Note that these codes are part of the SQL standard and only a small number 
of them will be used by PostgreSQL.

Common codes:

  00000 Successful completion
  25P01 No active SQL transaction
  25P02 In failed SQL transaction
  S8006 Connection failure

=head3 B<trace>

  $h->trace($trace_settings);
  $h->trace($trace_settings, $trace_filename);
  $trace_settings = $h->trace;

Changes the trace settings on a database or statement handle. 
The optional second argument specifies a file to write the 
trace information to. If no filename is given, the information 
is written to F<STDERR>. Note that tracing can be set globally as 
well by setting C<DBI-E<gt>trace>, or by using the environment 
variable I<DBI_TRACE>.

The value is either a numeric level or a named flag. For the 
flags that DBD::Pg uses, see L<parse_trace_flag|/parse_trace_flag and parse_trace_flags>.

=head3 B<trace_msg>

  $h->trace_msg($message_text);
  $h->trace_msg($message_text, $min_level);

Writes a message to the current trace output (as set by the L</trace> method). If a second argument 
is given, the message is only written if the current tracing level is equal to or greater than 
the C<$min_level>.

=head3 B<parse_trace_flag> and B<parse_trace_flags>

  $h->trace($h->parse_trace_flags('SQL|pglibpq'));
  $h->trace($h->parse_trace_flags('1|pgstart'));

  my $value = DBD::Pg->parse_trace_flag('pglibpq');
  DBI->trace($value);

The parse_trace_flags method is used to convert one or more named 
flags to a number which can passed to the L</trace> method.
DBD::Pg currently supports the DBI-specific flag, C<SQL>, 
as well as the ones listed below.

Flags can be combined by using the parse_trace_flags method, 
which simply calls C<parse_trace_flag> on each item and 
combines them.

Sometimes you may wish to turn the tracing on before you connect 
to the database. The second example above shows a way of doing this: 
the call to C<DBD::Pg-E<gt>parse_trace_flags> provides a number than can 
be fed to C<DBI-E<gt>trace> before you create a database handle.

DBD::Pg supports the following trace flags:

=over 4

=item SQL

Outputs all SQL statements. Note that the output provided will not 
necessarily be in a form suitable to passing directly to Postgres, 
as server-side prepared statements are used extensively by DBD::Pg.
For maximum portability of output (but with a potential performance 
hit), use with C<$dbh->{pg_server_prepare} = 0>

=item pglibpq

Outputs the name of each libpq function (without arguments) immediately 
before running it. This is a good way to trace the flow of your program 
at a low level. This information is also output if the trace level 
is set to 4 or greater.

=item pgstart

Outputs the name of each internal DBD::Pg function, and other information such as 
the function arguments or important global variables, as each function starts. This 
information is also output if the trace level is set to 4 or greater.

=item pgend

Outputs a simple message at the very end of each internal DBD::Pg function. This is also 
output if the trace level is set to 4 or greater.

=item pgprefix

Forces each line of trace output to begin with the string B<C<dbdpg: >>. This helps to 
differentiate it from the normal DBI trace output.

=item pglogin

Outputs a message showing the connection string right before a new database connection 
is attempted, a message when the connection was successful, and a message right after 
the database has been disconnected. Also output if trace level is 5 or greater.

=back

=for text See the DBI section on TRACING for more information.

=for html See the <a href="http://search.cpan.org/~timb/DBI/DBI.pm#TRACING">DBI section on TRACING</a> for more information.<br />

=head3 B<func>

DBD::Pg uses the C<func> method to support a variety of functions. 
Note that the name of the function comes I<last>, after the arguments.

=over

=item table_attributes

  $attrs = $dbh->func($table, 'table_attributes');

Use of the tables_attributes function is no longer recommended. Instead,
you can use the more portable C<column_info> and C<primary_key> methods
to access the same information.

The table_attributes method returns, for the given table argument, a
reference to an array of hashes, each of which contains the following keys:

  NAME        attribute name
  TYPE        attribute type
  SIZE        attribute size (-1 for variable size)
  NULLABLE    flag nullable
  DEFAULT     default value
  CONSTRAINT  constraint
  PRIMARY_KEY flag is_primary_key
  REMARKS     attribute description

=item lo_creat

  $lobjId = $dbh->func($mode, 'lo_creat');

Creates a new large object and returns the object-id. C<$mode> is a bitmask
describing different attributes of the new object. Use the following
constants:

  $dbh->{pg_INV_WRITE}
  $dbh->{pg_INV_READ}

Upon failure it returns C<undef>.

=item lo_open

  $lobj_fd = $dbh->func($lobjId, $mode, 'lo_open');

Opens an existing large object and returns an object-descriptor for use in
subsequent C<lo_*> calls. For the mode bits see L</lo_creat>. Returns C<undef>
upon failure. Note that 0 is a perfectly correct (and common) object descriptor!

=item lo_write

  $nbytes = $dbh->func($lobj_fd, $buffer, $len, 'lo_write');

Writes C<$len> bytes of c<$buffer> into the large object C<$lobj_fd>. Returns the number
of bytes written and C<undef> upon failure.

=item lo_read

  $nbytes = $dbh->func($lobj_fd, $buffer, $len, 'lo_read');

Reads C<$len> bytes into c<$buffer> from large object C<$lobj_fd>. Returns the number of
bytes read and C<undef> upon failure.

=item lo_lseek

  $loc = $dbh->func($lobj_fd, $offset, $whence, 'lo_lseek');

Changes the current read or write location on the large object
C<$obj_id>. Currently C<$whence> can only be 0 (which is L_SET). Returns the current
location and C<undef> upon failure.

=item lo_tell

  $loc = $dbh->func($lobj_fd, 'lo_tell');

Returns the current read or write location on the large object C<$lobj_fd> and C<undef> upon failure.

=item lo_close

  $lobj_fd = $dbh->func($lobj_fd, 'lo_close');

Closes an existing large object. Returns true upon success and false upon failure.

=item lo_unlink

  $ret = $dbh->func($lobjId, 'lo_unlink');

Deletes an existing large object. Returns true upon success and false upon failure.

=item lo_import

  $lobjId = $dbh->func($filename, 'lo_import');

Imports a Unix file as a large object and returns the object id of the new
object or C<undef> upon failure.

=item lo_export

  $ret = $dbh->func($lobjId, $filename, 'lo_export');

Exports a large object into a Unix file. Returns false upon failure, true otherwise.

=item getfd

  $fd = $dbh->func('getfd');

Deprecated, use L<$dbh-E<gt>{pg_socket}|/pg_socket> instead.

=back

=head3 B<private_attribute_info>

  $hashref = $dbh->private_attribute_info();
  $hashref = $sth->private_attribute_info();

Returns a hash of all private attributes used by DBD::Pg, for either 
a database or a statement handle. Currently, all the hash values are undef.

=head1 ATTRIBUTES COMMON TO ALL HANDLES

=head3 B<InactiveDestroy> (boolean)

If set to true, then the L</disconnect> method will not be automatically called when 
the database handle goes out of scope. This is required if you are forking, and even 
then you must tread carefully and ensure that either the parent or the child handles 
all database calls from that point forwards, so that messages from the Postgres backend 
are only handled by one of the processes. If you don't set things up properly, you 
will see messages such as "I<server closed the connection unexpectedly>". A better solution 
is usually to rewrite your application not to use forking. See the section on 
L</Asynchronous Queries> for a way to have your script continue to work while the database 
is processing a request.

=head3 B<RaiseError> (boolean, inherited)

Forces errors to always raise an exception. Although it defaults to off, it is recommended that this 
be turned on, as the alternative is to check the return value of every method (prepare, execute, fetch, etc.) 
to check for any problems. See the DBI docs for more information.

=head3 B<PrintError> (boolean, inherited)

Forces database errors to also generate warnings, which can then be filtered with methods such as 
locally redefining I<$SIG{__WARN__}> or using modules such as C<CGI::Carp>. This attribute is on 
by default.

=head3 B<ShowErrorStatement> (boolean, inherited)

Appends information about the current statement to error messages. If placeholder information 
is available, adds that as well. Defaults to false.

=head3 B<Warn> (boolean, inherited)

Enables warnings. This is on by default, and should only be turned off in a local block 
for a short a time only when absolutely needed.

=head3 B<Executed> (boolean, read-only)

Indicates if a handle has been executed. For database handles, this value is true after the L</do> method has been called, or 
when one of the child statement handles has issued an L</execute>. Issuing a L</commit> or L</rollback> always resets the 
attribute to false for database handles. For statement handles, any call to L</execute> or its variants will flip the value to 
true for the lifetime of the statement handle.

=head3 B<Type> (scalar)

Returns C<dr> for a driver handle, C<db> for a database handle, and C<st> for a statement handle. 
Should be rarely needed.

=head3 B<TraceLevel> (integer, inherited)

Sets the trace level, similar to the L</trace> method. See the sections on 
L</trace> and L</parse_trace_flag> for more details.

=head3 B<Active> (boolean, read-only)

Indicates if a handle is active or not. For database handles, this indicates if the database has 
been disconnected or not. For statement handles, it indicates if all the data has been fetched yet 
or not. Use of this attribute is not encouraged.

=head3 B<Kids> (integer, read-only)

Returns the number of child processes created for each handle type. For a driver handle, indicates the number 
of database handles created. For a database handle, indicates the number of statement handles created. For 
statement handles, it always returns zero, because statement handles do not create kids.

=head3 B<ActiveKids> (integer, read-only)

Same as C<Kids>, but only returns those that are active.

=head3 B<CachedKids> (hash ref)

Returns a hashref of handles. If called on a database handle, returns all statement handles created by use of the 
C<prepare_cached> method. If called on a driver handle, returns all database handles created by the L</connect_cached> 
method.

=head3 B<ChildHandles> (array ref)

Implemented by DBI, no driver-specific impact.

=head3 B<PrintWarn> (boolean, inherited)

Implemented by DBI, no driver-specific impact.

=head3 B<HandleError> (boolean, inherited)

Implemented by DBI, no driver-specific impact.

=head3 B<HandleSetErr> (code ref, inherited)

Implemented by DBI, no driver-specific impact.

=head3 B<ErrCount> (unsigned integer)

Implemented by DBI, no driver-specific impact.

=head3 B<FetchHashKeyName> (string, inherited)

Implemented by DBI, no driver-specific impact.

=head3 B<ChopBlanks> (boolean, inherited)

Supported by this driver as proposed by DBI. This method is similar to the
SQL function C<RTRIM>.

=head3 B<Taint> (boolean, inherited)

Implemented by DBI, no driver-specific impact.

=head3 B<TaintIn> (boolean, inherited)

Implemented by DBI, no driver-specific impact.

=head3 B<TaintOut> (boolean, inherited)

Implemented by DBI, no driver-specific impact.

=head3 B<Profile> (inherited)

Implemented by DBI, no driver-specific impact.

=head3 B<LongReadLen> (integer, inherited)

Not used by this driver.

=head3 B<LongTruncOk> (boolean, inherited)

Not used by this driver.

=head3 B<CompatMode> (boolean, inherited)

Not used by this driver.

=head1 DBI DATABASE HANDLE OBJECTS

=head2 Database Handle Methods

=head3 B<selectall_arrayref>

  $ary_ref = $dbh->selectall_arrayref($sql);
  $ary_ref = $dbh->selectall_arrayref($sql, \%attr);
  $ary_ref = $dbh->selectall_arrayref($sql, \%attr, @bind_values);

Returns a reference to an array containing the rows returned by preparing and executing the SQL string.
See the DBI documentation for full details. 

=head3 B<selectall_hashref>

  $hash_ref = $dbh->selectall_hashref($sql, $key_field);

Returns a reference to a hash containing the rows returned by preparing and executing the SQL string.
See the DBI documentation for full details. 

=head3 B<selectcol_arrayref>

  $ary_ref = $dbh->selectcol_arrayref($sql, \%attr, @bind_values);

Returns a reference to an array containing the first column 
from each rows returned by preparing and executing the SQL string. It is possible to specify exactly 
which columns to return. See the DBI documentation for full details. 

=head3 B<prepare>

  $sth = $dbh->prepare($statement, \%attr);

WARNING: DBD::Pg now (as of version 1.40) uses true prepared statements by sending them 
to the backend to be prepared by the Postgres server. Statements 
that were legal before may no longer work. See below for details.

The prepare method prepares a statement for later execution. PostgreSQL supports 
prepared statements, which enables DBD::Pg to only send the query once, and
simply send the arguments for every subsequent call to L</execute>.
DBD::Pg can use these server-side prepared statements, or it can
just send the entire query to the server each time. The best way
is automatically chosen for each query. This will be sufficient for
most users: keep reading for a more detailed explanation and some
optional flags.

Queries that do not begin with the word "SELECT", "INSERT", 
"UPDATE", or "DELETE" are never sent as server-side prepared statements.

Deciding whether or not to use prepared statements depends on many factors, 
but you can force them to be used or not used by using the 
L</pg_server_prepare> attribute when calling L</prepare>. Setting this to "0" means to never use 
prepared statements. Setting L</pg_server_prepare> to "1" means that prepared 
statements should be used whenever possible. This is the default when connected 
to Postgres servers version 8.0 or higher. Servers that are version 7.4 get a special 
default value of "2", because server-side statements were only partially supported 
in that version. In this case, it only uses server-side prepares if all 
parameters are specifically bound.

The L</pg_server_prepare> attribute can also be set at connection time like so:

  $dbh = DBI->connect($DBNAME, $DBUSER, $DBPASS,
                      { AutoCommit => 0,
                        RaiseError => 1,
                        pg_server_prepare => 0,
                      });

or you may set it after your database handle is created:

  $dbh->{pg_server_prepare} = 1;

To enable it for just one particular statement:

  $sth = $dbh->prepare("SELECT id FROM mytable WHERE val = ?",
                       { pg_server_prepare => 1 });

You can even toggle between the two as you go:

  $sth->{pg_server_prepare} = 1;
  $sth->execute(22);
  $sth->{pg_server_prepare} = 0;
  $sth->execute(44);
  $sth->{pg_server_prepare} = 1;
  $sth->execute(66);

In the above example, the first execute will use the previously prepared statement.
The second execute will not, but will build the query into a single string and send
it to the server. The third one will act like the first and only send the arguments.
Even if you toggle back and forth, a statement is only prepared once.

Using prepared statements is in theory quite a bit faster: not only does the
PostgreSQL backend only have to prepare the query only once, but DBD::Pg no
longer has to worry about quoting each value before sending it to the server.

However, there are some drawbacks. The server cannot always choose the ideal
parse plan because it will not know the arguments before hand. But for most
situations in which you will be executing similar data many times, the default
plan will probably work out well. Programs such as PgBouncer which cache connections 
at a low level should not use prepared statements via DBD::Pg, or must take 
extra care in the application to account for the fact that prepared statements 
are not shared across database connections. Further discussion on this subject is beyond
the scope of this documentation: please consult the pgsql-performance mailing
list, L<http://archives.postgresql.org/pgsql-performance/>

Only certain commands will be sent to a server-side prepare: currently these
include C<SELECT>, C<INSERT>, C<UPDATE>, and C<DELETE>. DBD::Pg uses a simple
naming scheme for the prepared statements themselves: B<dbdpg_XY_Z>, where B<Y> is the current 
PID, B<X> is either 'p' or 'n' (depending on if the PID is a positive or negative 
number), and B<Z> is a number that starts at 1 and increases each time a new statement 
is prepared. This number is tracked at the database handle level, so multiple
statement handles will not collide.

You cannot send more than one command at a time in the same prepare command 
(by separating them with semi-colons) when using server-side prepares.

The actual C<PREPARE> is usually not performed until the first execute is called, due
to the fact that information on the data types (provided by L</bind_param>) may
be provided after the prepare but before the execute.

A server-side prepare may happen before the first L</execute>, but only if the server can
handle the server-side prepare, and the statement contains no placeholders. It will 
also be prepared if the L</pg_prepare_now> attribute is passed in and set to a true 
value. Similarly, the L</pg_prepare_now> attribute can be set to 0 to ensure that
the statement is B<not> prepared immediately, although the cases in which you would
want this are very rare. Finally, you can set the default behavior of all prepare
statements by setting the L</pg_prepare_now> attribute on the database handle:

  $dbh->{pg_prepare_now} = 1;

The following two examples will be prepared right away:

  $sth->prepare("SELECT 123"); ## no placeholders

  $sth->prepare("SELECT 123, ?", {pg_prepare_now => 1});

The following two examples will NOT be prepared right away:

  $sth->prepare("SELECT 123, ?"); ## has a placeholder

  $sth->prepare("SELECT 123", {pg_prepare_now => 0});

There are times when you may want to prepare a statement yourself. To do this,
simply send the C<PREPARE> statement directly to the server (e.g. with
the L</do> method). Create a statement handle and set the prepared name via
the L</pg_prepare_name> attribute. The statement handle can be created with a dummy
statement, as it will not be executed. However, it should have the same
number of placeholders as your prepared statement. Example:

  $dbh->do("PREPARE mystat AS SELECT COUNT(*) FROM pg_class WHERE reltuples < ?");
  $sth = $dbh->prepare("SELECT ?");
  $sth->bind_param(1, 1, SQL_INTEGER);
  $sth->{pg_prepare_name} = "mystat";
  $sth->execute(123);

The above will run the equivalent of this query on the backend:

  EXECUTE mystat(123);

which is the equivalent of:

  SELECT COUNT(*) FROM pg_class WHERE reltuples < 123;

You can force DBD::Pg to send your query directly to the server by adding
the L</pg_direct> attribute to your prepare call. This is not recommended,
but is added just in case you need it.

=head3 B<Placeholders>

There are three types of placeholders that can be used in DBD::Pg. The first is
the "question mark" type, in which each placeholder is represented by a single
question mark character. This is the method recommended by the DBI specs and is the most
portable. Each question mark is internally replaced by a "dollar sign number" in the order
in which they appear in the query (important when using L</bind_param>).

The method second type of placeholder is "dollar sign numbers". This is the method
that Postgres uses internally and is overall probably the best method to use
if you do not need compatibility with other database systems. DBD::Pg, like
PostgreSQL, allows the same number to be used more than once in the query.
Numbers must start with "1" and increment by one value (but can appear in any order 
within the query). If the same number appears more than once in a query, it is treated as a 
single parameter and all instances are replaced at once. Examples:

Not legal:

  $SQL = 'SELECT count(*) FROM pg_class WHERE relpages > $2'; # Does not start with 1

  $SQL = 'SELECT count(*) FROM pg_class WHERE relpages BETWEEN $1 AND $3'; # Missing 2

Legal:

  $SQL = 'SELECT count(*) FROM pg_class WHERE relpages > $1';

  $SQL = 'SELECT count(*) FROM pg_class WHERE relpages BETWEEN $1 AND $2';

  $SQL = 'SELECT count(*) FROM pg_class WHERE relpages BETWEEN $2 AND $1'; # legal but confusing

  $SQL = 'SELECT count(*) FROM pg_class WHERE relpages BETWEEN $1 AND $2 AND reltuples > $1';

  $SQL = 'SELECT count(*) FROM pg_class WHERE relpages > $1 AND reltuples > $1';

In the final statement above, DBI thinks there is only one placeholder, so this
statement will replace both placeholders:

  $sth->bind_param(1, 2045);

While a simple execute with no bind_param calls requires only a single argument as well:

  $sth->execute(2045);

The final placeholder type is "named parameters" in the format ":foo". While this
syntax is supported by DBD::Pg, its use is discouraged in favor of 
dollar-sign numbers.

The different types of placeholders cannot be mixed within a statement, but you may
use different ones for each statement handle you have. This is confusing at best, so 
stick to one style within your program.

If your queries use operators that contain question marks (e.g. some of the native 
Postgres geometric operators) or array slices (e.g. C<data[100:300]>), you can tell 
DBD::Pg to ignore any non-dollar sign placeholders by setting the 
L</pg_placeholder_dollaronly> attribute at either the database handle or the statement 
handle level. Examples:

  $dbh->{pg_placeholder_dollaronly} = 1;
  $sth = $dbh->prepare(q{SELECT * FROM mytable WHERE lseg1 ?# lseg2 AND name = $1});
  $sth->execute('segname');

Alternatively, you can set it at prepare time:

  $sth = $dbh->prepare(q{SELECT * FROM mytable WHERE lseg1 ?-| lseg2 AND name = $1},
    {pg_placeholder_dollaronly = 1});
  $sth->execute('segname');

=head3 B<prepare_cached>

  $sth = $dbh->prepare_cached($statement, \%attr);

Implemented by DBI, no driver-specific impact. This method is most useful
when using a server that supports server-side prepares, and you have asked
the prepare to happen immediately via the L</pg_prepare_now> attribute.

=head3 B<do>

  $rv = $dbh->do($statement);
  $rv = $dbh->do($statement, \%attr);
  $rv = $dbh->do($statement, \%attr, @bind_values);

Prepare and execute a single statement. Returns the number of rows affected if the 
query was successful, returns undef if an error occurred, and returns -1 if the 
number of rows is unknown or not available. Note that this method will return B<0E0> instead
of 0 for 'no rows were affected', in order to always return a true value if no error occurred.

If neither C<\%attr> nor C<@bind_values> is given, the query will be sent directly
to the server without the overhead of internally creating a statement handle and
running prepare and execute, for a measurable speed increase.

Note that an empty statement (a string with no length) will not be passed to
the server; if you want a simple test, use "SELECT 123" or the L</ping> method.

=head3 B<last_insert_id>

  $rv = $dbh->last_insert_id(undef, $schema, $table, undef);
  $rv = $dbh->last_insert_id(undef, $schema, $table, undef, {sequence => $seqname});

Attempts to return the id of the last value to be inserted into a table.
You can either provide a sequence name (preferred) or provide a table
name with optional schema, and DBD::Pg will attempt to find the sequence itself. 
The current value of the sequence is returned by a call to the C<CURRVAL()> 
PostgreSQL function. This will fail if the sequence has not yet been used in the 
current database connection.

If you do not know the name of the sequence, you can provide a table name and
DBD::Pg will attempt to return the correct value. To do this, there must be at
least one column in the table with a C<NOT NULL> constraint, that has a unique
constraint, and which uses a sequence as a default value. If more than one column
meets these conditions, the primary key will be used. This involves some
looking up of things in the system table, so DBD::Pg will cache the sequence
name for subsequent calls. If you need to disable this caching for some reason,
(such as the sequence name changing), you can control it by adding C<pg_cache => 0> 
to the final (hashref) argument for last_insert_id.

Please keep in mind that this method is far from foolproof, so make your
script use it properly. Specifically, make sure that it is called
immediately after the insert, and that the insert does not add a value
to the column that is using the sequence as a default value. However, because 
we are using sequences, you can be sure that the value you got back has not 
been used by any other process.

Some examples:

  $dbh->do("CREATE SEQUENCE lii_seq START 1");
  $dbh->do("CREATE TABLE lii (
    foobar INTEGER NOT NULL UNIQUE DEFAULT nextval('lii_seq'),
    baz VARCHAR)");
  $SQL = "INSERT INTO lii(baz) VALUES (?)";
  $sth = $dbh->prepare($SQL);
  for (qw(uno dos tres cuatro)) {
    $sth->execute($_);
    my $newid = $dbh->last_insert_id(C<undef>,undef,undef,undef,{sequence=>'lii_seq'});
    print "Last insert id was $newid\n";
  }

If you did not want to worry about the sequence name:

  $dbh->do("CREATE TABLE lii2 (
    foobar SERIAL UNIQUE,
    baz VARCHAR)");
  $SQL = "INSERT INTO lii2(baz) VALUES (?)";
  $sth = $dbh->prepare($SQL);
  for (qw(uno dos tres cuatro)) {
    $sth->execute($_);
    my $newid = $dbh->last_insert_id(undef,undef,"lii2",undef);
    print "Last insert id was $newid\n";
  }

=head3 B<commit>

  $rv = $dbh->commit;

Issues a COMMIT to the server, indicating that the current transaction is finished and that 
all changes made will be visible to other processes. If AutoCommit is enabled, then 
a warning is given and no COMMIT is issued. Returns true on success, false on error.
See also the the section on L</Transactions>.

=head3 B<rollback>

  $rv = $dbh->rollback;

Issues a ROLLBACK to the server, which discards any changes made in the current transaction. If AutoCommit 
is enabled, then a warning is given and no ROLLBACK is issued. Returns true on success, and 
false on error. See also the the section on L</Transactions>.

=head3 B<begin_work>

This method turns on transactions until the next call to L</commit> or L</rollback>, if L</AutoCommit> is 
currently enabled. If it is not enabled, calling begin_work will issue an error. Note that the 
transaction will not actually begin until the first statement after begin_work is called.
Example:

  $dbh->{AutoCommit} = 1;
  $dbh->do("INSERT INTO foo VALUES (123)"); ## Changes committed immediately
  $dbh->begin_work();
  ## Not in a transaction yet, but AutoCommit is set to 0

  $dbh->do("INSERT INTO foo VALUES (345)");
  ## DBD::PG actually issues two statements here:
  ## BEGIN;
  ## INSERT INTO foo VALUES (345)
  ## We are now in a transaction

  $dbh->commit();
  ## AutoCommit is now set to 1 again

=head3 B<disconnect>

  $rv = $dbh->disconnect;

Disconnects from the Postgres database. Any uncommitted changes will be rolled back upon disconnection. It's 
good policy to always explicitly call commit or rollback at some point before disconnecting, rather than 
relying on the default rollback behavior.

This method may give warnings about "disconnect invalidates X active statement handle(s)". This means that 
you called C<$sth-E<gt>execute()> but did not finish fetching all the rows from them. To avoid seeing this 
warning, either fetch all the rows or call C<$sth-E<gt>finish()> for each executed statement handle.

If the script exits before disconnect is called (or, more precisely, if the database handle is no longer 
referenced by anything), then the database handle's DESTROY method will call the rollback() and disconnect() 
methods automatically. It is best to explicitly disconnect rather than rely on this behavior.

=head3 B<pg_notifies>

  $ret = $dbh->pg_notifies;

Looks for any asynchronous notifications received and returns either C<undef> 
or a reference to a three-element array consisting of an event name, the PID 
of the backend that sent the NOTIFY command, and the optional payload string. 
Note that this does not check if the connection to the database is still valid first - 
for that, use the c<ping> method. You may need to commit if not in autocommit mode - 
new notices will not be picked up while in the middle of a transaction. An example:

  $dbh->do("LISTEN abc");
  $dbh->do("LISTEN def");

  ## Hang around until we get the message we want
  LISTENLOOP: {
    while (my $notify = $dbh->pg_notifies) {
      my ($name, $pid, $payload) = @$notify;
      print qq{I received notice "$name" from PID $pid, payload was "$payload"\n};
      ## Do something based on the notice received
    }
    $dbh->ping() or die qq{Ping failed!};
    $dbh->commit();
    sleep(5);
    redo;
  }

Payloads will always be an empty string unless you are connecting to a Postgres 
server version 8.4 or higher.

=head3 B<ping>

  $rv = $dbh->ping;

This C<ping> method is used to check the validity of a database handle. The value returned is 
either 0, indicating that the connection is no longer valid, or a positive integer, indicating 
the following:

  Value    Meaning
  --------------------------------------------------
    1      Database is idle (not in a transaction)
    2      Database is active, there is a command in progress (usually seen after a COPY command)
    3      Database is idle within a transaction
    4      Database is idle, within a failed transaction

Additional information on why a handle is not valid can be obtained by using the 
L</pg_ping> method.

=head3 B<pg_ping>

  $rv = $dbh->pg_ping;

This is a DBD::Pg-specific extension to the L</ping> method. This will check the 
validity of a database handle in exactly the same way as C<ping>, but instead of 
returning a 0 for an invalid connection, it will return a negative number. So in 
addition to returning the positive numbers documented for C<ping>, it may also 
return the following:

  Value    Meaning
  --------------------------------------------------
   -1      There is no connection to the database at all (e.g. after C<disconnect>)
   -2      An unknown transaction status was returned (e.g. after forking)
   -3      The handle exists, but no data was returned from a test query.

In practice, you should only ever see -1 and -2.

=head3 B<get_info>

  $value = $dbh->get_info($info_type);

Supports a very large set (> 250) of the information types, including the minimum 
recommended by DBI.

=head3 B<table_info>

  $sth = $dbh->table_info(undef, $schema, $table, $type);

Returns all tables and views visible to the current user. 
The schema and table arguments will do a C<LIKE> search if a percent sign (C<%>) or an 
underscore (C<_>) is detected in the argument. The C<$type> argument accepts a value of either 
"TABLE" or "VIEW" (using both is the default action). Note that a statement handle is returned, 
and not a direct list of tables. See the examples below for ways to handle this.

The following fields are returned:

B<TABLE_CAT>: Always NULL, as Postgres does not have the concept of catalogs.

B<TABLE_SCHEM>: The name of the schema that the table or view is in.

B<TABLE_NAME>: The name of the table or view.

B<TABLE_TYPE>: The type of object returned. Will be one of "TABLE", "VIEW", 
or "SYSTEM TABLE".

The TABLE_SCHEM and TABLE_NAME will be quoted via C<quote_ident()>.

Two additional fields specific to DBD::Pg are returned:

B<pg_schema>: the unquoted name of the schema

B<pg_table>: the unquoted name of the table

If your database supports tablespaces (version 8.0 or greater), two additional
DBD::Pg specific fields are returned:

B<pg_tablespace_name>: the name of the tablespace the table is in

B<pg_tablespace_location>: the location of the tablespace the table is in

Tables that have not been assigned to a particular tablespace (or views) 
will return NULL (C<undef>) for both of the above field.

Rows are returned alphabetically, with all tables first, and then all views.

Examples of use:

  ## Display all tables and views in the public schema:
  $sth = $dbh->table_info('', 'public', undef, undef);
  for my $rel ({@$sth->fetchall_arrayref({})}) {
    print "$rel->{TABLE_TYPE} name is $rel->{TABLE_NAME}\n";
  }


  # Display the schema of all tables named 'foo':
  $sth = $dbh->table_info('', undef, 'foo', 'TABLE');
  for my $rel (@{$sth->fetchall_arrayref({})}) {
    print "Table name is $rel->{TABLE_SCHEM}.$rel->{TABLE_NAME}\n";
  }

=head3 B<column_info>

  $sth = $dbh->column_info( undef, $schema, $table, $column );

Supported by this driver as proposed by DBI with the follow exceptions.
These fields are currently always returned with NULL (C<undef>) values:

   TABLE_CAT
   BUFFER_LENGTH
   DECIMAL_DIGITS
   NUM_PREC_RADIX
   SQL_DATA_TYPE
   SQL_DATETIME_SUB
   CHAR_OCTET_LENGTH

Also, six additional non-standard fields are returned:

B<pg_type>: data type with additional info i.e. "character varying(20)"

B<pg_constraint>: holds column constraint definition

B<pg_schema>: the unquoted name of the schema

B<pg_table>: the unquoted name of the table

B<pg_column>: the unquoted name of the column

B<pg_enum_values>: an array reference of allowed values for an enum column

Note that the TABLE_SCHEM, TABLE_NAME, and COLUMN_NAME fields all return 
output wrapped in quote_ident(). If you need the unquoted version, use 
the pg_ fields above.

=head3 B<primary_key_info>

  $sth = $dbh->primary_key_info( undef, $schema, $table, \%attr );

Supported by this driver as proposed by DBI. There are no search patterns allowed, but leaving the 
$schema argument blank will cause the first table found in the schema 
search path to be used. An additional field, "DATA_TYPE", is returned and 
shows the data type for each of the arguments in the "COLUMN_NAME" field.

This method will also return tablespace information for servers that support
tablespaces. See the L</table_info> entry for more information.

The five additional custom fields returned are:

B<pg_tablespace_name>: name of the tablespace, if any

B<pg_tablespace_location>: location of the tablespace

B<pg_schema>: the unquoted name of the schema

B<pg_table>: the unquoted name of the table

B<pg_column>: the unquoted name of the column

In addition to the standard format of returning one row for each column
found for the primary key, you can pass the C<pg_onerow> attribute to force
a single row to be used. If the primary key has multiple columns, the
"KEY_SEQ", "COLUMN_NAME", and "DATA_TYPE" fields will return a comma-delimited
string. If the C<pg_onerow> attribute is set to "2", the fields will be
returned as an arrayref, which can be useful when multiple columns are
involved:

  $sth = $dbh->primary_key_info('', '', 'dbd_pg_test', {pg_onerow => 2});
  if (defined $sth) {
    my $pk = $sth->fetchall_arrayref()->[0];
    print "Table $pk->[2] has a primary key on these columns:\n";
    for (my $x=0; defined $pk->[3][$x]; $x++) {
      print "Column: $pk->[3][$x]  (data type: $pk->[6][$x])\n";
    }
  }

=head3 B<primary_key>

  @key_column_names = $dbh->primary_key(undef, $schema, $table);

Simple interface to the L</primary_key_info> method. Returns a list of the column names that 
comprise the primary key of the specified table. The list is in primary key column sequence 
order. If there is no primary key then an empty list is returned.

=head3 B<foreign_key_info>

  $sth = $dbh->foreign_key_info( $pk_catalog, $pk_schema, $pk_table,
                                 $fk_catalog, $fk_schema, $fk_table );

Supported by this driver as proposed by DBI, using the SQL/CLI variant.
There are no search patterns allowed, but leaving the C<$schema> argument
blank will cause the first table found in the schema search path to be
used. Two additional fields, "UK_DATA_TYPE" and "FK_DATA_TYPE", are returned
to show the data type for the unique and foreign key columns. Foreign
keys that have no named constraint (where the referenced column only has
an unique index) will return C<undef> for the "UK_NAME" field.

=head3 B<statistics_info>

  $sth = $dbh->statistics_info( undef, $schema, $table, $unique_only, $quick );

Returns a statement handle that can be fetched from to give statistics information 
on a specific table and its indexes. The C<$table> argument is mandatory. The 
C<$schema> argument is optional but recommended. The C<$unique_only> argument, if true, 
causes only information about unique indexes to be returned. The C<$quick> argument is 
not used by DBD::Pg. For information on the format of the rows returned, please see the DBI 
documentation.

=for html <a href="http://search.cpan.org/~timb/DBI/DBI.pm#statistics_info">DBI section on statistics_info</a>

=head3 B<tables>

  @names = $dbh->tables( undef, $schema, $table, $type, \%attr );

Supported by this driver as proposed by DBI. This method returns all tables
and/or views which are visible to the current user: see L</table_info>
for more information about the arguments. The name of the schema appears 
before the table or view name. This can be turned off by adding in the 
C<pg_noprefix> attribute:

  my @tables = $dbh->tables( '', '', 'dbd_pg_test', '', {pg_noprefix => 1} );

=head3 B<type_info_all>

  $type_info_all = $dbh->type_info_all;

Supported by this driver as proposed by DBI. Information is only provided for
SQL datatypes and for frequently used datatypes. The mapping between the
PostgreSQL typename and the SQL92 datatype (if possible) has been done
according to the following table:

  +---------------+------------------------------------+
  | typname       | SQL92                              |
  |---------------+------------------------------------|
  | bool          | BOOL                               |
  | text          | /                                  |
  | bpchar        | CHAR(n)                            |
  | varchar       | VARCHAR(n)                         |
  | int2          | SMALLINT                           |
  | int4          | INT                                |
  | int8          | /                                  |
  | money         | /                                  |
  | float4        | FLOAT(p)   p<7=float4, p<16=float8 |
  | float8        | REAL                               |
  | abstime       | /                                  |
  | reltime       | /                                  |
  | tinterval     | /                                  |
  | date          | /                                  |
  | time          | /                                  |
  | datetime      | /                                  |
  | timespan      | TINTERVAL                          |
  | timestamp     | TIMESTAMP                          |
  +---------------+------------------------------------+

=head3 B<type_info>

  @type_info = $dbh->type_info($data_type);

Implemented by DBI, no driver-specific impact.

=head3 B<quote>

  $rv = $dbh->quote($value, $data_type);

This module implements its own C<quote> method. For simple string types, both backslashes 
and single quotes are doubled. You may also quote arrayrefs and receive a string 
suitable for passing into Postgres array columns.

If the value contains backslashes, and the server is version 8.1 or higher, 
then the escaped string syntax will be used (which places a capital E before 
the first single quote). This syntax is always used when quoting bytea values 
on servers 8.1 and higher.

The C<data_type> argument is optional and should be one of the type constants 
exported by DBD::Pg (such as PG_BYTEA). In addition to string, bytea, char, bool, 
and other standard types, the following geometric types are supported: point, line, 
lseg, box, path, polygon, and circle (PG_POINT, PG_LINE, PG_LSEG, PG_BOX, 
PG_POLYGON, and PG_CIRCLE respectively).

B<NOTE:> The undocumented (and invalid) support for the C<SQL_BINARY> data
type is officially deprecated. Use C<PG_BYTEA> with C<bind_param()> instead:

  $rv = $sth->bind_param($param_num, $bind_value,
                         { pg_type => PG_BYTEA });

=head3 B<quote_identifier>

  $string = $dbh->quote_identifier( $name );
  $string = $dbh->quote_identifier( undef, $schema, $table);

Returns a quoted version of the supplied string, which is commonly a schema, 
table, or column name. The three argument form will return the schema and 
the table together, separated by a dot. Examples:

  print $dbh->quote_identifier('grapefruit'); ## Prints: "grapefruit"

  print $dbh->quote_identifier('juicy fruit'); ## Prints: "juicy fruit"

  print $dbh->quote_identifier(undef, 'public', 'pg_proc');
  ## Prints: "public"."pg_proc"

=head3 B<pg_server_trace>

  $dbh->pg_server_trace($filehandle);

Writes debugging information from the PostgreSQL backend to a file. This is
not related to the DBI L</trace> method and you should not use this method unless
you know what you are doing. If you do enable this, be aware that the file
will grow very large, very quick. To stop logging to the file, use the
L</pg_server_untrace> method. The first argument must be a file handle, not
a filename. Example:

  my $pid = $dbh->{pg_pid};
  my $file = "pgbackend.$pid.debug.log";
  open(my $fh, ">$file") or die qq{Could not open "$file": $!\n};
  $dbh->pg_server_trace($fh);
  ## Run code you want to trace here
  $dbh->pg_server_untrace;
  close($fh);

=head3 B<pg_server_untrace>

  $dbh->pg_server_untrace;

Stop server logging to a previously opened file.

=head3 B<selectrow_array>

  @row_ary = $dbh->selectrow_array($sql);
  @row_ary = $dbh->selectrow_array($sql, \%attr);
  @row_ary = $dbh->selectrow_array($sql, \%attr, @bind_values);

Returns an array of row information after preparing and executing the provided SQL string. The rows are returned 
by calling L</fetchrow_array>. The string can also be a statement handle generated by a previous prepare. Note that 
only the first row of data is returned. If called in a scalar context, only the first column of the first row is 
returned. Because this is not portable, it is not recommended that you use this method in that way.

=head3 B<selectrow_arrayref>

  $ary_ref = $dbh->selectrow_arrayref($statement);
  $ary_ref = $dbh->selectrow_arrayref($statement, \%attr);
  $ary_ref = $dbh->selectrow_arrayref($statement, \%attr, @bind_values);

Exactly the same as L</selectrow_array>, except that it returns a reference to an array, by internal use of 
the L</fetchrow_arrayref> method.

=head3 B<selectrow_hashref>

  $hash_ref = $dbh->selectrow_hashref($sql);
  $hash_ref = $dbh->selectrow_hashref($sql, \%attr);
  $hash_ref = $dbh->selectrow_hashref($sql, \%attr, @bind_values);

Exactly the same as L</selectrow_array>, except that it returns a reference to an hash, by internal use of 
the L</fetchrow_hashref> method.

=head3 B<clone>

  $other_dbh = $dbh->clone();

Creates a copy of the database handle by connecting with the same parameters as the original 
handle, then trying to merge the attributes. See the DBI documentation for complete usage.

=head2 Database Handle Attributes

=head3 B<AutoCommit> (boolean)

Supported by this driver as proposed by DBI. According to the classification of
DBI, PostgreSQL is a database in which a transaction must be explicitly
started. Without starting a transaction, every change to the database becomes
immediately permanent. The default of AutoCommit is on, but this may change
in the future, so it is highly recommended that you explicitly set it when
calling L</connect>. For details see the notes about L</Transactions>
elsewhere in this document.

=head3 B<pg_bool_tf> (boolean)

DBD::Pg specific attribute. If true, boolean values will be returned
as the characters 't' and 'f' instead of '1' and '0'.

=head3 B<ReadOnly> (boolean)

$dbh->{ReadOnly} = 1;

Specifies if the current database connection should be in read-only mode or not. 
In this mode, changes that change the database are not allowed and will throw 
an error. Note: this method will B<not> work if L</AutoCommit> is true. The 
read-only effect is accomplished by sending a S<SET TRANSACTION READ ONLY> after 
every begin. For more details, please see:

http://www.postgresql.org/docs/current/interactive/sql-set-transaction.html

Please not that this method is not foolproof: there are still ways to update the 
database. Consider this a safety net to catch applications that should not be 
issuing commands such as INSERT, UPDATE, or DELETE.

This method method requires DBI version 1.55 or better.

=head3 B<Name> (string, read-only)

Returns the name of the current database.

=head3 B<Username> (string, read-only)

Returns the name of the user connected to the database.

=head3 B<pg_enable_utf8> (boolean)

DBD::Pg specific attribute. If true, then the C<utf8> flag will be turned
for returned character data (if the data is valid UTF-8). For details about
the C<utf8> flag, see the C<Encode> module. This attribute is only relevant under
perl 5.8 and later.

=head3 B<pg_errorlevel> (integer)

DBD::Pg specific attribute. Sets the amount of information returned by the server's 
error messages. Valid entries are 0, 1, and 2. Any other number will be forced to the 
default value of 1.

A value of 0 ("TERSE") will show severity, primary text, and position only
and will usually fit on a single line. A value of 1 ("DEFAULT") will also
show any detail, hint, or context fields. A value of 2 ("VERBOSE") will
show all available information.

=head3 B<pg_protocol> (integer, read-only)

DBD::Pg specific attribute. Returns the version of the PostgreSQL server.
If DBD::Pg is unable to figure out the version, it will return a "0". Otherwise,
a "3" is returned.

=head3 B<pg_lib_version> (integer, read-only)

DBD::Pg specific attribute. Indicates which version of PostgreSQL that 
DBD::Pg was compiled against. In other words, which libraries were used. 
Returns a number with major, minor, and revision together; version 8.1.4 
would be returned as C<80104>.

=head3 B<pg_server_version> (integer, read-only)

DBD::Pg specific attribute. Indicates which version of PostgreSQL that 
the current database handle is connected to. Returns a number with major, 
minor, and revision together; version 8.0.1 would be C<80001>.

=head3 B<pg_db> (string, read-only)

DBD::Pg specific attribute. Returns the name of the current database.

=head3 B<pg_user> (string, read-only)

DBD::Pg specific attribute. Returns the name of the user that
connected to the server.

=head3 B<pg_pass> (string, read-only)

DBD::Pg specific attribute. Returns the password used to connect
to the server.

=head3 B<pg_host> (string, read-only)

DBD::Pg specific attribute. Returns the host of the current
server connection. Locally connected hosts will return an empty
string.

=head3 B<pg_port> (integer, read-only)

DBD::Pg specific attribute. Returns the port of the connection to
the server.

=head3 B<pg_default_port> (integer, read-only)

DBD::Pg specific attribute. Returns the default port used if none is
specifically given.

=head3 B<pg_options> (string, read-only)

DBD::Pg specific attribute. Returns the command-line options passed
to the server. May be an empty string.

=head3 B<pg_socket> (integer, read-only)

DBD::Pg specific attribute. Returns the file description number of
the connection socket to the server.

=head3 B<pg_pid> (integer, read-only)

DBD::Pg specific attribute. Returns the process id (PID) of the
backend server process handling the connection.

=head3 B<pg_prepare_now> (boolean)

DBD::Pg specific attribute. Default is off. If true, then the L</prepare> method will 
immediately prepare commands, rather than waiting until the first execute.

=head3 B<pg_server_prepare> (integer)

DBD::Pg specific attribute. Indicates if DBD::Pg should attempt to use server-side 
prepared statements. The default value, 1, indicates that prepared statements should 
be used whenever possible. See the section on the L</prepare> method for more information.

=head3 B<pg_placeholder_dollaronly> (boolean)

DBD::Pg specific attribute. Defaults to false. When true, question marks inside of statements 
are not treated as L</placeholders>. Useful for statements that contain unquoted question 
marks, such as geometric operators.

=head3 B<pg_expand_array> (boolean, read-only)

DBD::Pg specific attribute. Defaults to false. If false, arrays returned from the server will 
not be changed into a Perl arrayref, but remain as a string.

=head3 B<pg_async_status> (integer, read-only)

DBD::Pg specific attribute. Returns the current status of an L<asynchronous|/Asynchronous Queries>
command. 0 indicates no asynchronous command is in progress, 1 indicates that 
an asynchronous command has started and -1 indicated that an asynchronous command 
has been cancelled.

=head3 B<pg_standard_conforming_strings> (boolean, read-only)

DBD::Pg specific attribute. Returns true if the server is currently using 
standard conforming strings. Only available if the target 
server is version 8.2 or better.

=head3 B<pg_INV_READ> (integer, read-only)

Constant to be used for the mode in L</lo_creat> and L</lo_open>.

=head3 B<pg_INV_WRITE> (integer, read-only)

Constant to be used for the mode in L</lo_creat> and L</lo_open>.

=head3 B<Driver> (handle)

Holds the handle of the parent driver. The only recommended use for this is to find the name 
of the driver using:

  $dbh->{Driver}->{Name}

=head3 B<RowCacheSize> (integer)

Not used for DBD::Pg

=head1 DBI STATEMENT HANDLE OBJECTS

=head2 Statement Handle Methods

=head3 B<bind_param>

  $rv = $sth->bind_param($param_num, $bind_value);
  $rv = $sth->bind_param($param_num, $bind_value, $bind_type);
  $rv = $sth->bind_param($param_num, $bind_value, \%attr);

Allows the user to bind a value and/or a data type to a placeholder. This is
especially important when using server-side prepares. See the 
L</prepare> method for more information.

The value of C<$param_num> is a number if using the '?' or '$1' style
placeholders. If using ":foo" style placeholders, the complete name
(e.g. ":foo") must be given. For numeric values, you can either use a
number or use a literal '$1'. See the examples below.

The C<$bind_value> argument is fairly self-explanatory. A value of C<undef> will
bind a C<NULL> to the placeholder. Using C<undef> is useful when you want
to change just the type and will be overwriting the value later.
(Any value is actually usable, but C<undef> is easy and efficient).

The C<\%attr> hash is used to indicate the data type of the placeholder.
The default value is "varchar". If you need something else, you must
use one of the values provided by DBI or by DBD::Pg. To use a SQL value,
modify your "use DBI" statement at the top of your script as follows:

  use DBI qw(:sql_types);

This will import some constants into your script. You can plug those
directly into the C<bind_param> call. Some common ones that you will
encounter are:

  SQL_INTEGER

To use PostgreSQL data types, import the list of values like this:

  use DBD::Pg qw(:pg_types);

You can then set the data types by setting the value of the C<pg_type>
key in the hash passed to C<bind_param>. 
The current list of Postgres data types exported is:

 PG_ABSTIME PG_ABSTIMEARRAY PG_ACLITEM PG_ACLITEMARRAY PG_ANY PG_ANYARRAY
 PG_ANYELEMENT PG_ANYENUM PG_ANYNONARRAY PG_BIT PG_BITARRAY PG_BOOL
 PG_BOOLARRAY PG_BOX PG_BOXARRAY PG_BPCHAR PG_BPCHARARRAY PG_BYTEA
 PG_BYTEAARRAY PG_CHAR PG_CHARARRAY PG_CID PG_CIDARRAY PG_CIDR
 PG_CIDRARRAY PG_CIRCLE PG_CIRCLEARRAY PG_CSTRING PG_CSTRINGARRAY PG_DATE
 PG_DATEARRAY PG_FLOAT4 PG_FLOAT4ARRAY PG_FLOAT8 PG_FLOAT8ARRAY PG_GTSVECTOR
 PG_GTSVECTORARRAY PG_INET PG_INETARRAY PG_INT2 PG_INT2ARRAY PG_INT2VECTOR
 PG_INT2VECTORARRAY PG_INT4 PG_INT4ARRAY PG_INT8 PG_INT8ARRAY PG_INTERNAL
 PG_INTERVAL PG_INTERVALARRAY PG_LANGUAGE_HANDLER PG_LINE PG_LINEARRAY PG_LSEG
 PG_LSEGARRAY PG_MACADDR PG_MACADDRARRAY PG_MONEY PG_MONEYARRAY PG_NAME
 PG_NAMEARRAY PG_NUMERIC PG_NUMERICARRAY PG_OID PG_OIDARRAY PG_OIDVECTOR
 PG_OIDVECTORARRAY PG_OPAQUE PG_PATH PG_PATHARRAY PG_PG_ATTRIBUTE PG_PG_CLASS
 PG_PG_PROC PG_PG_TYPE PG_POINT PG_POINTARRAY PG_POLYGON PG_POLYGONARRAY
 PG_RECORD PG_REFCURSOR PG_REFCURSORARRAY PG_REGCLASS PG_REGCLASSARRAY PG_REGCONFIG
 PG_REGCONFIGARRAY PG_REGDICTIONARY PG_REGDICTIONARYARRAY PG_REGOPER PG_REGOPERARRAY PG_REGOPERATOR
 PG_REGOPERATORARRAY PG_REGPROC PG_REGPROCARRAY PG_REGPROCEDURE PG_REGPROCEDUREARRAY PG_REGTYPE
 PG_REGTYPEARRAY PG_RELTIME PG_RELTIMEARRAY PG_SMGR PG_TEXT PG_TEXTARRAY
 PG_TID PG_TIDARRAY PG_TIME PG_TIMEARRAY PG_TIMESTAMP PG_TIMESTAMPARRAY
 PG_TIMESTAMPTZ PG_TIMESTAMPTZARRAY PG_TIMETZ PG_TIMETZARRAY PG_TINTERVAL PG_TINTERVALARRAY
 PG_TRIGGER PG_TSQUERY PG_TSQUERYARRAY PG_TSVECTOR PG_TSVECTORARRAY PG_TXID_SNAPSHOT
 PG_TXID_SNAPSHOTARRAY PG_UNKNOWN PG_UUID PG_UUIDARRAY PG_VARBIT PG_VARBITARRAY
 PG_VARCHAR PG_VARCHARARRAY PG_VOID PG_XID PG_XIDARRAY PG_XML
 PG_XMLARRAY

Data types are "sticky," in that once a data type is set to a certain placeholder,
it will remain for that placeholder, unless it is explicitly set to something
else afterwards. If the statement has already been prepared, and you switch the
data type to something else, DBD::Pg will re-prepare the statement for you before
doing the next execute.

Examples:

  use DBI qw(:sql_types);
  use DBD::Pg qw(:pg_types);

  $SQL = "SELECT id FROM ptable WHERE size > ? AND title = ?";
  $sth = $dbh->prepare($SQL);

  ## Both arguments below are bound to placeholders as "varchar"
  $sth->execute(123, "Merk");

  ## Reset the datatype for the first placeholder to an integer
  $sth->bind_param(1, undef, SQL_INTEGER);

  ## The "undef" bound above is not used, since we supply params to execute
  $sth->execute(123, "Merk");

  ## Set the first placeholder's value and data type
  $sth->bind_param(1, 234, { pg_type => PG_TIMESTAMP });

  ## Set the second placeholder's value and data type.
  ## We don't send a third argument, so the default "varchar" is used
  $sth->bind_param('$2', "Zool");

  ## We realize that the wrong data type was set above, so we change it:
  $sth->bind_param('$1', 234, { pg_type => SQL_INTEGER });

  ## We also got the wrong value, so we change that as well.
  ## Because the data type is sticky, we don't need to change it
  $sth->bind_param(1, 567);

  ## This executes the statement with 567 (integer) and "Zool" (varchar)
  $sth->execute();

=head3 B<bind_param_inout>

  $rv = $sth->bind_param_inout($param_num, \$scalar, 0);


Experimental support for this feature is provided. The first argument to 
bind_param_inout should be a placeholder number. The second argument 
should be a reference to a scalar variable in your script. The third argument 
is not used and should simply be set to 0. Note that what this really does is 
assign a returned column to the variable, in the order in which the column 
appears. For example:

  my $foo = 123;
  $sth = $dbh->prepare("SELECT 1+?::int");
  $sth->bind_param_inout(1, \$foo, 0);
  $foo = 222;
  $sth->execute(444);
  $sth->fetch;

The above will cause $foo to have a new value of "223" after the final fetch.
Note that the variables bound in this manner are very sticky, and will trump any 
values passed in to execute. This is because the binding is done as late as possible, 
at the execute() stage, allowing the value to be changed between the time it was bound 
and the time the query is executed. Thus, the above execute is the same as:

  $sth->execute();

=head3 B<bind_param_array>


  $rv = $sth->bind_param_array($param_num, $array_ref_or_value)
  $rv = $sth->bind_param_array($param_num, $array_ref_or_value, $bind_type)
  $rv = $sth->bind_param_array($param_num, $array_ref_or_value, \%attr)

Binds an array of values to a placeholder, so that each is used in turn by a call 
to the L</execute_array> method.

=head3 B<execute>

  $rv = $sth->execute(@bind_values);

Executes a previously prepared statement. In addition to C<UPDATE>, C<DELETE>,
C<INSERT> statements, for which it returns always the number of affected rows,
the C<execute> method can also be used for C<SELECT ... INTO table> statements.

The "prepare/bind/execute" process has changed significantly for PostgreSQL
servers 7.4 and later: please see the C<prepare()> and C<bind_param()> entries for
much more information.

Setting one of the bind_values to "undef" is the equivalent of setting the value 
to NULL in the database. Setting the bind_value to $DBDPG_DEFAULT is equivalent 
to sending the literal string 'DEFAULT' to the backend. Note that using this 
option will force server-side prepares off until such time as PostgreSQL 
supports using DEFAULT in prepared statements.

DBD::Pg also supports passing in arrays to execute: simply pass in an arrayref, 
and DBD::Pg will flatten it into a string suitable for input on the backend.

If you are using Postgres version 8.2 or greater, you can also use any of the 
fetch methods to retrieve the values of a C<RETURNING> clause after you execute 
an C<UPDATE>, C<DELETE>, or C<INSERT>. For example:

  $dbh->do(q{CREATE TABLE abc (id SERIAL, country TEXT)});
  $SQL = q{INSERT INTO abc (country) VALUES (?) RETURNING id};
  $sth = $dbh->prepare($SQL);
  $sth->execute('France');
  $countryid = $sth->fetch()->[0];
  $sth->execute('New Zealand');
  $countryid = $sth->fetch()->[0];

=head3 B<execute_array>

  $tuples = $sth->execute_array() or die $sth->errstr;
  $tuples = $sth->execute_array(\%attr) or die $sth->errstr;
  $tuples = $sth->execute_array(\%attr, @bind_values) or die $sth->errstr;

  ($tuples, $rows) = $sth->execute_array(\%attr) or die $sth->errstr;
  ($tuples, $rows) = $sth->execute_array(\%attr, @bind_values) or die $sth->errstr;

Execute a prepared statement once for each item in a passed-in hashref, or items that 
were previously bound via the L</bind_param_array> method. See the DBI documentation 
for more details.

=head3 B<execute_for_fetch>

  $tuples = $sth->execute_for_fetch($fetch_tuple_sub);
  $tuples = $sth->execute_for_fetch($fetch_tuple_sub, \@tuple_status);

  ($tuples, $rows) = $sth->execute_for_fetch($fetch_tuple_sub);
  ($tuples, $rows) = $sth->execute_for_fetch($fetch_tuple_sub, \@tuple_status);

Used internally by the L</execute_array> method, and rarely used directly. See the 
DBI documentation for more details.

=head3 B<fetchrow_arrayref>

  $ary_ref = $sth->fetchrow_arrayref;

Fetches the next row of data from the statement handle, and returns a reference to an array 
holding the column values. Any columns that are NULL are returned as undef within the array.

If there are no more rows or if an error occurs, the this method return undef. You should 
check C<$sth-E<gt>err> afterwards (or use the L</RaiseError> attribute) to discover if the undef returned 
was due to an error.

Note that the same array reference is returned for each fetch, so don't store the reference and 
then use it after a later fetch. Also, the elements of the array are also reused for each row, 
so take care if you want to take a reference to an element. See also L</bind_columns>.

=head3 B<fetchrow_array>

  @ary = $sth->fetchrow_array;

Similar to the L</fetchrow_arrayref> method, but returns a list of column information rather than 
a reference to a list. Do not use this in a scalar context.

=head3 B<fetchrow_hashref>

  $hash_ref = $sth->fetchrow_hash