# $Id: Pg.pm,v 1.43 2001/05/27 14:10:13 mergl Exp $
#
# Copyright (c) 1997,1998,1999,2000 Edmund Mergl
# Portions Copyright (c) 1994,1995,1996,1997 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.
require 5.003;
$DBD::Pg::VERSION = '1.00';
{
package DBD::Pg;
use DBI ();
use DynaLoader ();
use Exporter ();
@ISA = qw(DynaLoader Exporter);
require_version DBI 1.00;
bootstrap DBD::Pg $VERSION;
$err = 0; # holds error code for DBI::err
$errstr = ""; # holds error string for DBI::errstr
$drh = undef; # holds driver handle once initialized
sub driver{
return $drh if $drh;
my($class, $attr) = @_;
$class .= "::dr";
# not a 'my' since we use it above to prevent multiple drivers
$drh = DBI::_new_drh($class, {
'Name' => 'Pg',
'Version' => $VERSION,
'Err' => \$DBD::Pg::err,
'Errstr' => \$DBD::Pg::errstr,
'Attribution' => 'PostgreSQL DBD by Edmund Mergl',
});
$drh;
}
1;
}
{ package DBD::Pg::dr; # ====== DRIVER ======
use strict;
sub data_sources {
my $drh = shift;
my $dbh = DBD::Pg::dr::connect($drh, 'dbname=template1') or return undef;
$dbh->{AutoCommit} = 1;
my $sth = $dbh->prepare("SELECT datname FROM pg_database ORDER BY datname") or return undef;
$sth->execute or return undef;
my (@sources, @datname);
while (@datname = $sth->fetchrow_array) {
push @sources, "dbi:Pg:dbname=$datname[0]";
}
$sth->finish;
$dbh->disconnect;
return @sources;
}
sub connect {
my($drh, $dbname, $user, $auth)= @_;
# create a 'blank' dbh
my $Name = $dbname;
$Name =~ s/^.*dbname\s*=\s*//;
$Name =~ s/\s*;.*$//;
$user = "" unless defined($user);
$auth = "" unless defined($auth);
$user = $ENV{DBI_USER} if $user eq "";
$auth = $ENV{DBI_PASS} if $auth eq "";
$user = "" unless defined($user);
$auth = "" unless defined($auth);
my($dbh) = DBI::_new_dbh($drh, {
'Name' => $Name,
'User' => $user, 'CURRENT_USER' => $user,
});
# Connect to the database..
DBD::Pg::db::_login($dbh, $dbname, $user, $auth) or return undef;
$dbh;
}
}
{ package DBD::Pg::db; # ====== DATABASE ======
use strict;
use POSIX(qw(isprint)); # necessary for quote()
sub prepare {
my($dbh, $statement, @attribs)= @_;
# create a 'blank' sth
my $sth = DBI::_new_sth($dbh, {
'Statement' => $statement,
});
DBD::Pg::st::_prepare($sth, $statement, @attribs) or return undef;
$sth;
}
sub ping {
my($dbh) = @_;
local $SIG{__WARN__} = sub { } if $dbh->{PrintError};
local $dbh->{RaiseError} = 0 if $dbh->{RaiseError};
my $ret = DBD::Pg::db::_ping($dbh);
return $ret;
}
sub table_info { # DBI spec: TABLE_CAT, TABLE_SCHEM, TABLE_NAME, TABLE_TYPE, REMARKS
my($dbh) = @_;
my $sth = $dbh->prepare("
SELECT c.reltype, u.usename, c.relname, 'TABLE', ''
FROM pg_class c, pg_user u
WHERE c.relkind = 'r'
AND c.relhasrules = FALSE
AND c.relname !~ '^pg_'
AND c.relname !~ '^xin[vx][0-9]+'
AND c.relowner = u.usesysid
UNION
SELECT c.reltype, u.usename, c.relname, 'VIEW', ''
FROM pg_class c, pg_user u
WHERE c.relkind = 'r'
AND c.relhasrules = TRUE
AND c.relname !~ '^pg_'
AND c.relname !~ '^xin[vx][0-9]+'
AND c.relowner = u.usesysid
ORDER BY 1, 2, 3
") or return undef;
$sth->execute or return undef;
$sth;
}
sub tables {
my($dbh) = @_;
my $sth = $dbh->prepare("
select relname
from pg_class
where relkind = 'r'
and relname !~ '^pg_'
and relname !~ '^xin[vx][0-9]+'
order by 1
") or return undef;
$sth->execute or return undef;
my (@tables, @relname);
while (@relname = $sth->fetchrow_array) {
push @tables, $relname[0];
}
$sth->finish;
return @tables;
}
sub table_attributes {
my ($dbh, $table) = @_;
my $result = [];
my $attrs = $dbh->selectall_arrayref(
"select a.attname, t.typname, a.attlen, a.atttypmod, a.attnotnull, a.atthasdef, a.attnum
from pg_attribute a,
pg_class c,
pg_type t
where c.relname = '$table'
and a.attrelid = c.oid
and a.attnum >= 0
and t.oid = a.atttypid
order by 1
");
return $result unless scalar(@$attrs);
# Get the primary key
my ($pri_key) = $dbh->selectrow_array("SELECT pg_attribute.attname
FROM pg_class, pg_attribute, pg_index
WHERE pg_class.oid = pg_attribute.attrelid
AND pg_class.oid = pg_index.indrelid
AND pg_index.indkey[0] = pg_attribute.attnum
AND pg_index.indisprimary = 't'
AND pg_class.relname = '$table'");
$pri_key = '' unless $pri_key;
foreach my $attr (reverse @$attrs) {
my ($col_name, $col_type, $size, $mod, $notnull, $hasdef, $attnum) = @$attr;
my $col_size = do {
if ($size > 0) {
$size;
} elsif ($mod > 0xffff) {
my $prec = ($mod & 0xffff) - 4;
$mod >>= 16;
my $dig = $mod;
$dig;
} elsif ($mod >= 4) {
$mod - 4;
} else {
$mod;
}
};
# Get the default value, if any
my ($default) = $dbh->selectrow_array("SELECT adsrc FROM pg_attrdef WHERE adnum = $attnum") if -1 == $attnum;
$default = '' unless $default;
# Test for any constraints
my ($constraint) = $dbh->selectrow_array("select rcsrc from pg_relcheck where rcname = '${table}_$col_name'");
$constraint = '' unless $constraint;
# Check to see if this is the primary key
my $is_primary_key = (lc $pri_key eq lc $col_name) ? 1 : 0;
push @$result,
{ NAME => $col_name,
TYPE => $col_type,
SIZE => $col_size,
NOTNULL => $notnull,
DEFAULT => $default,
CONSTRAINT => $constraint,
PRIMARY_KEY => $is_primary_key,
};
}
return $result;
}
sub type_info_all {
my ($dbh) = @_;
my $names = {
TYPE_NAME => 0,
DATA_TYPE => 1,
PRECISION => 2,
LITERAL_PREFIX => 3,
LITERAL_SUFFIX => 4,
CREATE_PARAMS => 5,
NULLABLE => 6,
CASE_SENSITIVE => 7,
SEARCHABLE => 8,
UNSIGNED_ATTRIBUTE => 9,
MONEY =>10,
AUTO_INCREMENT =>11,
LOCAL_TYPE_NAME =>12,
MINIMUM_SCALE =>13,
MAXIMUM_SCALE =>14,
};
# typname |typlen|typprtlen| SQL92
# --------------+------+---------+ -------
# bool | 1| 1| BOOLEAN
# text | -1| -1| like VARCHAR, but automatic storage allocation
# bpchar | -1| -1| CHARACTER(n) bp=blank padded
# varchar | -1| -1| VARCHAR(n)
# int2 | 2| 5| SMALLINT
# int4 | 4| 10| INTEGER
# int8 | 8| 20| /
# money | 4| 24| /
# float4 | 4| 12| FLOAT(p) for p<7=float4, for p<16=float8
# float8 | 8| 24| REAL
# abstime | 4| 20| /
# reltime | 4| 20| /
# tinterval | 12| 47| /
# date | 4| 10| /
# time | 8| 16| /
# datetime | 8| 47| /
# timespan | 12| 47| INTERVAL
# timestamp | 4| 19| TIMESTAMP
# --------------+------+---------+
# DBI type definitions / PostgreSQL definitions # type needs to be DBI-specific (not pg_type)
#
# SQL_ALL_TYPES 0
# SQL_CHAR 1 1042 bpchar
# SQL_NUMERIC 2 700 float4
# SQL_DECIMAL 3 700 float4
# SQL_INTEGER 4 23 int4
# SQL_SMALLINT 5 21 int2
# SQL_FLOAT 6 700 float4
# SQL_REAL 7 701 float8
# SQL_DOUBLE 8 20 int8
# SQL_DATE 9 1082 date
# SQL_TIME 10 1083 time
# SQL_TIMESTAMP 11 1296 timestamp
# SQL_VARCHAR 12 1043 varchar
my $ti = [
$names,
# name type prec prefix suffix create params null case se unsign mon incr local min max
#
[ 'bytea', -2, 4096, '\'', '\'', undef, 1, '1', 3, undef, '0', '0', 'BYTEA', undef, undef ],
[ 'bool', 0, 1, '\'', '\'', undef, 1, '0', 2, undef, '0', '0', 'BOOLEAN', undef, undef ],
[ 'int8', 8, 20, undef, undef, undef, 1, '0', 2, '0', '0', '0', 'LONGINT', undef, undef ],
[ 'int2', 5, 5, undef, undef, undef, 1, '0', 2, '0', '0', '0', 'SMALLINT', undef, undef ],
[ 'int4', 4, 10, undef, undef, undef, 1, '0', 2, '0', '0', '0', 'INTEGER', undef, undef ],
[ 'text', 12, 4096, '\'', '\'', undef, 1, '1', 3, undef, '0', '0', 'TEXT', undef, undef ],
[ 'float4', 6, 12, undef, undef, 'precision', 1, '0', 2, '0', '0', '0', 'FLOAT', undef, undef ],
[ 'float8', 7, 24, undef, undef, 'precision', 1, '0', 2, '0', '0', '0', 'REAL', undef, undef ],
[ 'abstime', 10, 20, '\'', '\'', undef, 1, '0', 2, undef, '0', '0', 'ABSTIME', undef, undef ],
[ 'reltime', 10, 20, '\'', '\'', undef, 1, '0', 2, undef, '0', '0', 'RELTIME', undef, undef ],
[ 'tinterval', 11, 47, '\'', '\'', undef, 1, '0', 2, undef, '0', '0', 'TINTERVAL', undef, undef ],
[ 'money', 0, 24, undef, undef, undef, 1, '0', 2, undef, '1', '0', 'MONEY', undef, undef ],
[ 'bpchar', 12, 4096, '\'', '\'', 'max length', 1, '1', 3, undef, '0', '0', 'CHARACTER', undef, undef ],
[ 'varchar', 12, 4096, '\'', '\'', 'max length', 1, '1', 3, undef, '0', '0', 'VARCHAR', undef, undef ],
[ 'date', 9, 10, '\'', '\'', undef, 1, '0', 2, undef, '0', '0', 'DATE', undef, undef ],
[ 'time', 10, 16, '\'', '\'', undef, 1, '0', 2, undef, '0', '0', 'TIME', undef, undef ],
[ 'datetime', 11, 47, '\'', '\'', undef, 1, '0', 2, undef, '0', '0', 'DATETIME', undef, undef ],
[ 'timespan', 11, 47, '\'', '\'', undef, 1, '0', 2, undef, '0', '0', 'INTERVAL', undef, undef ],
[ 'timestamp', 10, 19, '\'', '\'', undef, 1, '0', 2, undef, '0', '0', 'TIMESTAMP', undef, undef ]
#
# intentionally omitted: char, all geometric types, all array types
];
return $ti;
}
sub quote {
my ($dbh, $str, $data_type) = @_;
return "NULL" unless defined $str;
unless ($data_type) {
$str =~ s/'/''/g; # ISO SQL2
# In addition to the DBI method it doubles also the
# backslash, because PostgreSQL treats a backslash as an
# escape character.
$str =~ s/\\/\\\\/g;
return "'$str'";
}
# Optimise for standard numerics which need no quotes
return $str if $data_type == DBI::SQL_INTEGER
|| $data_type == DBI::SQL_SMALLINT
|| $data_type == DBI::SQL_DECIMAL
|| $data_type == DBI::SQL_FLOAT
|| $data_type == DBI::SQL_REAL
|| $data_type == DBI::SQL_DOUBLE
|| $data_type == DBI::SQL_NUMERIC;
my $ti = $dbh->type_info($data_type);
# XXX needs checking
my $lp = $ti ? $ti->{LITERAL_PREFIX} || "" : "'";
my $ls = $ti ? $ti->{LITERAL_SUFFIX} || "" : "'";
# XXX don't know what the standard says about escaping
# in the 'general case' (where $lp != "'").
# So we just do this and hope:
$str =~ s/$lp/$lp$lp/g
if $lp && $lp eq $ls && ($lp eq "'" || $lp eq '"');
# also, escape the backslashes, always
$str =~ s/\\/\\\\/g;
# if the type is SQL_BINARY, escape the non-printable chars
if ($data_type == DBI::SQL_BINARY ||
$data_type == DBI::SQL_VARBINARY ||
$data_type == DBI::SQL_LONGVARBINARY) {
$str=join("", map { isprint($_)?$_:'\\'.sprintf("%03o",ord($_)) }
split //, $str);
}
return "$lp$str$ls";
}
}
{ package DBD::Pg::st; # ====== STATEMENT ======
# all done in XS
}
1;
__END__
=head1 NAME
DBD::Pg - PostgreSQL database driver for the DBI module
=head1 SYNOPSIS
use DBI;
$dbh = DBI->connect("dbi:Pg:dbname=$dbname", "", "");
# See the DBI module documentation for full details
=head1 DESCRIPTION
DBD::Pg is a Perl module which 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 DBI documentation first !
=head1 THE DBI CLASS
=head2 DBI Class Methods
=over 4
=item B<connect>
To connect to a database with a minimum of parameters, use the
following syntax:
$dbh = DBI->connect("dbi:Pg:dbname=$dbname", "", "");
This connects to the database $dbname at localhost without any user
authentication. This is sufficient for the defaults of PostgreSQL.
The following connect statement shows all possible parameters:
$dbh = DBI->connect("dbi:Pg:dbname=$dbname;host=$host;port=$port;options=$options;tty=$tty", "$username", "$password");
If a parameter is undefined PostgreSQL first looks for specific environment
variables and then it uses hard coded defaults:
parameter environment variable hard coded default
--------------------------------------------------
dbname PGDATABASE current userid
host PGHOST localhost
port PGPORT 5432
options PGOPTIONS ""
tty PGTTY ""
username PGUSER current userid
password PGPASSWORD ""
If a host is specified, the postmaster on this host needs to be
started with the C<-i> option (TCP/IP sockets).
The options parameter specifies runtime options for the Postgres
backend. Common usage is to increase the number of buffers with
the C<-B> option. Also important is the C<-F> option, which disables
automatiic fsync() call after each transaction. For further details
please refer to the L<postgres>.
For authentication with username and password appropriate entries have
to be made in pg_hba.conf. Please refer to the L<pg_hba.conf> and the
L<pg_passwd> for the different types of authentication. Note that for
these two parameters DBI distinguishes between empty and undefined. If
these parameters are undefined DBI substitutes the values of the environment
variables DBI_USER and DBI_PASS if present.
=item B<available_drivers>
@driver_names = DBI->available_drivers;
Implemented by DBI, no driver-specific impact.
=item B<data_sources>
@data_sources = DBI->data_sources('Pg');
The driver supports this method. Note, that the necessary database
connect to the database template1 will be done on the localhost
without any user-authentication. Other preferences can only be set
with the environment variables PGHOST, DBI_USER and DBI_PASS.
=item B<trace>
DBI->trace($trace_level, $trace_file)
Implemented by DBI, no driver-specific impact.
=back
=head2 DBI Dynamic Attributes
See Common Methods.
=head1 METHODS COMMON TO ALL HANDLES
=over 4
=item B<err>
$rv = $h->err;
Supported by the driver as proposed by DBI. For the connect
method it returns PQstatus. In all other cases it returns
PQresultStatus of the current handle.
=item B<errstr>
$str = $h->errstr;
Supported by the driver as proposed by DBI. It returns the
PQerrorMessage related to the current handle.
=item B<state>
$str = $h->state;
This driver does not (yet) support the state method.
=item B<trace>
$h->trace($trace_level, $trace_filename);
Implemented by DBI, no driver-specific impact.
=item B<trace_msg>
$h->trace_msg($message_text);
Implemented by DBI, no driver-specific impact.
=item B<func>
This driver supports a variety of driver specific functions
accessible via the func interface:
$attrs = $dbh->func($table, 'table_attributes');
This method returns for the given table a reference to an
array of hashes:
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
$lobjId = $dbh->func($mode, 'lo_creat');
Creates a new large object and returns the object-id. $mode is a
bit-mask describing different attributes of the new object. Use
the following constants:
$dbh->{pg_INV_WRITE}
$dbh->{pg_INV_READ}
Upon failure it returns undef.
$lobj_fd = $dbh->func($lobjId, $mode, 'lo_open');
Opens an existing large object and returns an object-descriptor
for use in subsequent lo_* calls.
For the mode bits see lo_create. Returns undef upon failure.
Note, that 0 is a perfectly correct object descriptor !
$nbytes = $dbh->func($lobj_fd, $buf, $len, 'lo_write');
Writes $len bytes of $buf into the large object $lobj_fd.
Returns the number of bytes written and undef upon failure.
$nbytes = $dbh->func($lobj_fd, $buf, $len, 'lo_read');
Reads $len bytes into $buf from large object $lobj_fd.
Returns the number of bytes read and undef upon failure.
$loc = $dbh->func($lobj_fd, $offset, $whence, 'lo_lseek');
Change the current read or write location on the large
object $obj_id. Currently $whence can only be 0 (L_SET).
Returns the current location and undef upon failure.
$loc = $dbh->func($lobj_fd, 'lo_tell');
Returns the current read or write location on the large
object $lobj_fd and undef upon failure.
$lobj_fd = $dbh->func($lobj_fd, 'lo_close');
Closes an existing large object. Returns true upon success
and false upon failure.
$lobj_fd = $dbh->func($lobj_fd, 'lo_unlink');
Deletes an existing large object. Returns true upon success
and false upon failure.
$lobjId = $dbh->func($filename, 'lo_import');
Imports a Unix file as large object and returns the object
id of the new object or undef upon failure.
$ret = $dbh->func($lobjId, 'lo_export', 'filename');
Exports a large object into a Unix file. Returns false upon
failure, true otherwise.
$ret = $dbh->func($line, 'putline');
Used together with the SQL-command 'COPY table FROM STDIN' to
copy large amount of data into a table avoiding the overhead
of using single insert-comands. The application must explicitly
send the two characters "\." to indicate to the backend that
it has finished sending its data. See test.pl for an example
on how to use this function.
$ret = $dbh->func($buffer, length, 'getline');
Used together with the SQL-command 'COPY table TO STDOUT' to
dump a complete table. See test.pl for an example on how to use
this function.
=back
=head1 ATTRIBUTES COMMON TO ALL HANDLES
=over 4
=item B<Warn> (boolean, inherited)
Implemented by DBI, no driver-specific impact.
=item B<Active> (boolean, read-only)
Supported by the driver as proposed by DBI. A database
handle is active while it is connected and statement
handle is active until it is finished.
=item B<Kids> (integer, read-only)
Implemented by DBI, no driver-specific impact.
=item B<ActiveKids> (integer, read-only)
Implemented by DBI, no driver-specific impact.
=item B<CachedKids> (hash ref)
Implemented by DBI, no driver-specific impact.
=item B<CompatMode> (boolean, inherited)
Not used by this driver.
=item B<InactiveDestroy> (boolean)
Implemented by DBI, no driver-specific impact.
=item B<PrintError> (boolean, inherited)
Implemented by DBI, no driver-specific impact.
=item B<RaiseError> (boolean, inherited)
Implemented by DBI, no driver-specific impact.
=item B<ChopBlanks> (boolean, inherited)
Supported by the driver as proposed by DBI. This
method is similar to the SQL-function RTRIM.
=item B<LongReadLen> (integer, inherited)
Implemented by DBI, not used by the driver.
=item B<LongTruncOk> (boolean, inherited)
Implemented by DBI, not used by the driver.
=item B<Taint> (boolean, inherited)
Implemented by DBI, no driver-specific impact.
=item B<private_*>
Implemented by DBI, no driver-specific impact.
=back
=head1 DBI DATABASE HANDLE OBJECTS
=head2 Database Handle Methods
=over 4
=item B<selectrow_array>
@row_ary = $dbh->selectrow_array($statement, \%attr, @bind_values);
Implemented by DBI, no driver-specific impact.
=item B<selectall_arrayref>
$ary_ref = $dbh->selectall_arrayref($statement, \%attr, @bind_values);
Implemented by DBI, no driver-specific impact.
=item B<selectcol_arrayref>
$ary_ref = $dbh->selectcol_arrayref($statement, \%attr, @bind_values);
Implemented by DBI, no driver-specific impact.
=item B<prepare>
$sth = $dbh->prepare($statement, \%attr);
PostgreSQL does not have the concept of preparing
a statement. Hence the prepare method just stores
the statement after checking for place-holders.
No information about the statement is available
after preparing it.
=item B<prepare_cached>
$sth = $dbh->prepare_cached($statement, \%attr);
Implemented by DBI, no driver-specific impact.
This method is not useful for this driver, because
preparing a statement has no database interaction.
=item B<do>
$rv = $dbh->do($statement, \%attr, @bind_values);
Implemented by DBI, no driver-specific impact. See the
notes for the execute method elsewhere in this document.
=item B<commit>
$rc = $dbh->commit;
Supported by the driver as proposed by DBI. See also the
notes about B<Transactions> elsewhere in this document.
=item B<rollback>
$rc = $dbh->rollback;
Supported by the driver as proposed by DBI. See also the
notes about B<Transactions> elsewhere in this document.
=item B<disconnect>
$rc = $dbh->disconnect;
Supported by the driver as proposed by DBI.
=item B<ping>
$rc = $dbh->ping;
This driver supports the ping-method, which can be used to check the
validity of a database-handle. The ping method issues an empty query
and checks the result status.
=item B<table_info>
$sth = $dbh->table_info;
Supported by the driver as proposed by DBI. This
method returns all tables and views which are owned by the
current user. It does not select any indices and sequences.
Also System tables are not selected. As TABLE_QUALIFIER the
reltype attribute is returned and the REMARKS are undefined.
=item B<tables>
@names = $dbh->tables;
Supported by the driver as proposed by DBI. This
method returns all tables and views which are owned by the
current user. It does not select any indices and sequences.
Also system tables are not selected.
=item B<type_info_all>
$type_info_all = $dbh->type_info_all;
Supported by the driver as proposed by DBI.
Only for SQL data-types and for frequently used data-types
information is provided. The mapping between the PostgreSQL typename
and the SQL92 data-type (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 |
+---------------+------------------------------------+
For further details concerning the PostgreSQL specific data-types
please read the L<pgbuiltin>.
=item B<type_info>
@type_info = $dbh->type_info($data_type);
Implemented by DBI, no driver-specific impact.
=item B<quote>
$sql = $dbh->quote($value, $data_type);
This module implements it's own quote method. In addition to the
DBI method it doubles also the backslash, because PostgreSQL treats
a backslash as an escape character.
=back
=head2 Database Handle Attributes
=over 4
=item B<AutoCommit> (boolean)
Supported by the 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, which corresponds
to the default behavior of PostgreSQL. When setting AutoCommit
to off, a transaction will be started and every commit or rollback
will automatically start a new transaction. For details see the
notes about B<Transactions> elsewhere in this document.
=item B<Driver> (handle)
Implemented by DBI, no driver-specific impact.
=item B<Name> (string, read-only)
The default method of DBI is overridden by a driver specific
method, which returns only the database name. Anything else
from the connection string is stripped off. Note, that here
the method is read-only in contrast to the DBI specs.
=item B<RowCacheSize> (integer)
Implemented by DBI, not used by the driver.
=item B<pg_auto_escape> (boolean)
PostgreSQL specific attribute. If true, then quotes and backslashes in all
parameters will be escaped in the following way:
escape quote with a quote (SQL)
escape backslash with a backslash
The default is on. Note, that PostgreSQL also accepts quotes, which
are escaped by a backslash. Any other ASCII character can be used
directly in a string constant.
=item B<pg_INV_READ> (integer, read-only)
Constant to be used for the mode in lo_creat and lo_open.
=item B<pg_INV_WRITE> (integer, read-only)
Constant to be used for the mode in lo_creat and lo_open.
=back
=head1 DBI STATEMENT HANDLE OBJECTS
=head2 Statement Handle Methods
=over 4
=item B<bind_param>
$rv = $sth->bind_param($param_num, $bind_value, \%attr);
Supported by the driver as proposed by DBI.
=item B<bind_param_inout>
Not supported by this driver.
=item B<execute>
$rv = $sth->execute(@bind_values);
Supported by the driver as proposed by DBI.
In addition to 'UPDATE', 'DELETE', 'INSERT' statements, for
which it returns always the number of affected rows, the execute
method can also be used for 'SELECT ... INTO table' statements.
=item B<fetchrow_arrayref>
$ary_ref = $sth->fetchrow_arrayref;
Supported by the driver as proposed by DBI.
=item B<fetchrow_array>
@ary = $sth->fetchrow_array;
Supported by the driver as proposed by DBI.
=item B<fetchrow_hashref>
$hash_ref = $sth->fetchrow_hashref;
Supported by the driver as proposed by DBI.
=item B<fetchall_arrayref>
$tbl_ary_ref = $sth->fetchall_arrayref;
Implemented by DBI, no driver-specific impact.
=item B<finish>
$rc = $sth->finish;
Supported by the driver as proposed by DBI.
=item B<rows>
$rv = $sth->rows;
Supported by the driver as proposed by DBI.
In contrast to many other drivers the number of rows is
available immediately after executing the statement.
=item B<bind_col>
$rc = $sth->bind_col($column_number, \$var_to_bind, \%attr);
Supported by the driver as proposed by DBI.
=item B<bind_columns>
$rc = $sth->bind_columns(\%attr, @list_of_refs_to_vars_to_bind);
Supported by the driver as proposed by DBI.
=item B<dump_results>
$rows = $sth->dump_results($maxlen, $lsep, $fsep, $fh);
Implemented by DBI, no driver-specific impact.
=item B<blob_read>
$blob = $sth->blob_read($id, $offset, $len);
Supported by this driver as proposed by DBI. Implemented by DBI
but not documented, so this method might change.
This method seems to be heavily influenced by the current implementation
of blobs in Oracle. Nevertheless we try to be as compatible as possible.
Whereas Oracle suffers from the limitation that blobs are related to tables
and every table can have only one blob (data-type LONG), PostgreSQL handles
its blobs independent of any table by using so called object identifiers.
This explains why the blob_read method is blessed into the STATEMENT package
and not part of the DATABASE package. Here the field parameter has been used
to handle this object identifier. The offset and len parameter may be set to
zero, in which case the driver fetches the whole blob at once.
Starting with PostgreSQL-6.5 every access to a blob has to be put into a
transaction. This holds even for a read-only access.
See also the PostgreSQL-specific functions concerning blobs which are
available via the func-interface.
For further information and examples about blobs, please read the chapter
about Large Objects in the PostgreSQL Programmer's Guide.
=back
=head2 Statement Handle Attributes
=over 4
=item B<NUM_OF_FIELDS> (integer, read-only)
Implemented by DBI, no driver-specific impact.
=item B<NUM_OF_PARAMS> (integer, read-only)
Implemented by DBI, no driver-specific impact.
=item B<NAME> (array-ref, read-only)
Supported by the driver as proposed by DBI.
=item B<NAME_lc> (array-ref, read-only)
Implemented by DBI, no driver-specific impact.
=item B<NAME_uc> (array-ref, read-only)
Implemented by DBI, no driver-specific impact.
=item B<TYPE> (array-ref, read-only)
Supported by the driver as proposed by DBI, with
the restriction, that the types are PostgreSQL
specific data-types which do not correspond to
international standards.
=item B<PRECISION> (array-ref, read-only)
Not supported by the driver.
=item B<SCALE> (array-ref, read-only)
Not supported by the driver.
=item B<NULLABLE> (array-ref, read-only)
Not supported by the driver.
=item B<CursorName> (string, read-only)
Not supported by the driver. See the note about
B<Cursors> elsewhere in this document.
=item B<Statement> (string, read-only)
Supported by the driver as proposed by DBI.
=item B<RowCache> (integer, read-only)
Not supported by the driver.
=item B<pg_size> (array-ref, read-only)
PostgreSQL specific attribute. It returns a reference to an
array of integer values for each column. The integer shows
the size of the column in bytes. Variable length columns
are indicated by -1.
=item B<pg_type> (hash-ref, read-only)
PostgreSQL specific attribute. It returns a reference to an
array of strings for each column. The string shows the name
of the data_type.
=item B<pg_oid_status> (integer, read-only)
PostgreSQL specific attribute. It returns the OID of the last
INSERT command.
=item B<pg_cmd_status> (integer, read-only)
PostgreSQL specific attribute. It returns the type of the last
command. Possible types are: INSERT, DELETE, UPDATE, SELECT.
=back
=head1 FURTHER INFORMATION
=head2 Transactions
The transaction behavior is now controlled with the attribute AutoCommit.
For a complete definition of AutoCommit please refer to the DBI documentation.
According to the DBI specification the default for AutoCommit is TRUE.
In this mode, any change to the database becomes valid immediately. Any
'begin', 'commit' or 'rollback' statement will be rejected.
If AutoCommit is switched-off, immediately a transaction will be started by
issuing a 'begin' statement. Any 'commit' or 'rollback' will start a new
transaction. A disconnect will issue a 'rollback' statement.
=head2 Large Objects
The driver supports all large-objects related functions provided by
libpq via the func-interface. Please note, that starting with
PoostgreSQL-65. any access to a large object - even read-only -
has to be put into a transaction !
=head2 Cursors
Although PostgreSQL has a cursor concept, it has not
been used in the current implementation. Cursors in
PostgreSQL can only be used inside a transaction block.
Because only one transaction block at a time is allowed,
this would have implied the restriction, not to use
any nested SELECT statements. Hence the execute method
fetches all data at once into data structures located
in the frontend application. This has to be considered
when selecting large amounts of data !
=head2 Data-Type bool
The current implementation of PostgreSQL returns 't' for true and 'f' for
false. From the perl point of view a rather unfortunate choice. The DBD-Pg
module translates the result for the data-type bool in a perl-ish like manner:
'f' -> '0' and 't' -> '1'. This way the application does not have to check
the database-specific returned values for the data-type bool, because perl
treats '0' as false and '1' as true.
PostgreSQL Version 6.2 considers the input 't' as true
and anything else as false.
PostgreSQL Version 6.3 considers the input 't', '1' and 1 as true
and anything else as false.
PostgreSQL Version 6.4 considers the input 't', '1' and 'y' as true
and any other character as false.
=head1 SEE ALSO
L<DBI>
=head1 AUTHORS
=item *
DBI and DBD-Oracle by Tim Bunce (Tim.Bunce@ig.co.uk)
=item *
DBD-Pg by Edmund Mergl (E.Mergl@bawue.de)
Major parts of this package have been copied from DBI and DBD-Oracle.
=head1 COPYRIGHT
The DBD::Pg module is free software.
You may distribute under the terms of either the GNU General Public
License or the Artistic License, as specified in the Perl README file.
=head1 ACKNOWLEDGMENTS
See also B<DBI/ACKNOWLEDGMENTS>.
=cut