README

DBD::Pg is Copyright (C) 1994-2024, Greg Sabino Mullane

DBD::Pg  --  the DBI PostgreSQL interface for Perl

DESCRIPTION:
------------

This is version 3.18.0 of DBD::Pg, the Perl interface to Postgres using DBI.
The web site for this interface, and the latest version, can be found at:

	http://search.cpan.org/dist/DBD-Pg/

The mailing list is at:

    http://www.nntp.perl.org/group/perl.dbd.pg/

Subscribe with an email to dbd-pg-subscribe@perl.org


The development of DBD::Pg can be tracked at:

    git://github.com/bucardo/dbdpg.git

For information about PostgreSQL, visit:

	http://www.postgresql.org/

For information on what has changed for each version, see the Changes files.


REQUIREMENTS:
-------------

	build, test, and install Perl 5         (at least 5.8.1)
	build, test, and install the DBI module (at least 1.614)
	build, test, and install PostgreSQL     (at least 8.0)
	build, test, and install Test::Simple   (at least 0.47)

DBD::Pg needs to know where to find the libpq libraries: this is usually done 
by checking the output of the pg_config executable. If pg_config is not available, 
then you may need to install the development package for PostgreSQL. To do this 
on Debian and Ubuntu, use: apt-get install libpq-dev; on RedHat, CentOS, etc. 
use: yum install postgresql-devel. Note that the development libraries are needed 
even if you already have PostgreSQL up and running.


IF YOU HAVE PROBLEMS OR COMMENTS:
---------------------------------

Please send any problems and comments to 

<dbd-pg@perl.org>

Please include what OS you are using, and the version of Perl, 
DBI, and DBD::Pg you are using. Also tell which version of 
PostgreSQL DBD::Pg was compiled against, and which version you 
are connecting to. The easiest way to gather all of this 
information is to run "make test", which outputs it all early in 
the tests.

View the archive at http://www.nntp.perl.org/group/perl.dbd.pg/

To subscribe, email dbd-pg-subscribe@perl.org
To unsubscribe, email dbd-pg-unsubscribe@perl.org
To get help regarding your subscription, email dbd-pg-help@perl.org

You can also try the #postgresql channel on irc.libera.chat, which 
usually (but not always) has people who can help you with DBD::Pg.


BUG REPORTS:
-----------

Bug reports are welcome at:

https://github.com/bucardo/dbdpg/issues


PATCHES:
--------

Patches are always welcome: the best way is to create a Pull Request 
at https://github.com/bucardo/dbdpg


INSTALLATION:
-------------

Before installing, please use the "cpansign -v" program to cryptographically 
verify that your copy of DBD::Pg is complete and valid. The program 
"cpansign" is part of Module::Signature, available from CPAN.

By default Makefile.PL uses App::Info to find the location of the
PostgreSQL library and include directories.  However, if you want to
control it yourself, define the environment variables POSTGRES_INCLUDE 
and POSTGRES_LIB, or define just POSTGRES_HOME. Note that if you have 
compiled PostgreSQL with SSL support, you must define the POSTGRES_LIB
environment variable and add "-lssl" and "-lcrypto" to it, like this:

	export POSTGRES_LIB="/usr/local/pgsql/lib -lssl -lcrypto"

The usual steps to install DBD::Pg:

	1.   perl Makefile.PL
	2.   make
	3.   make test
	4.   make install

Do steps 1 to 2 as a normal user, not as root!

If the script cannot find the pg_config information itself, it will 
ask you for the path to it. Enter the complete path to the pg_config 
file here, including the name of the file itself.


TESTING:
--------

The tests rely on being able to connect to a valid Postgres database. 
The easiest way to ensure this is to set the following environment variables:

	DBI_DSN=dbi:Pg:dbname=<database>
	DBI_USER=<username>
	DBI_PASS=<password>

If you are running on a non-standard port, you must set PGPORT or 
add the port to the DBI_DSN variable like this:

	DBI_DSN='dbi:Pg:dbname=<database>;port=<port#>'

Put double quotes around the dbname if it has a semicolon 
or a space inside of it:

	DBI_DSN='dbi:Pg:dbname="<data;base>"'

If no valid connection is found, the tests will use the "initdb" 
program to try and create a Postgres database cluster to test with.
The first available port starting at 5440 will be used.

If your directory path is long, Postgres may fail to start as there is a
maximum length to socket directory paths. If this happens, please set
the environment variable DBDPG_TEMPDIR to something short, such as "/tmp".

You can increase the verbosity of the tests by setting the 
environment variable TEST_VERBOSE. You can also enable tracing 
within the tests themselves by setting DBD_TRACE to whatever 
trace level you want. Be aware that setting the trace level can 
result in extremely verbose output.

When reporting test failures, please use TEST_VERBOSE=1, but do *not* 
set DBD_TRACE unless requested, and send only the relevant sections.

Please consider installing CPAN::Reporter so that your tests are 
automatically gathered and reported, which helps the development 
of DBD::Pg.


TROUBLESHOOTING:
----------------

* Placeholder issues

If you find that some of your queries containing placeholders are no 
longer working, this may because DBD::Pg now uses the native PostgreSQL 
placeholders on the server itself whenever possible. Previously, DBD::Pg 
did a simple emulation of placeholders, so the rules were not as strict.
You should either rewrite your queries to make them legal SQL syntax for 
PostgreSQL, or turn off server-side prepares.

To change your queries, make sure that the type of each placeholder can 
be determined by the PostgreSQL parser. So instead of:

  SELECT ?

use something like:

  SELECT ?::int

To turn off server-side prepares completely (with a loss of some performance 
and features), do this at the top of your scripts:

$dbh->{pg_server_prepare} = 0;

This can also be set for individual queries at the statement handle level: see 
the documentation section on "Placeholders" for more details.


* PostgreSQL library issues:

DBD::Pg uses the libpq library that comes with Postgres. If the shared libpq 
library is not available, DBD::Pg will error with a message that 
usually mentions a file names libpq.so, like this:

    Can't load './blib/arch/auto/DBD/Pg/Pg.so' for module DBD::Pg: libpq.so.5: cannot open 
    shared object file: No such file or directory at .../DynaLoader.pm line 230.

This means that the libraries are not installed in a place where the system 
can find them when it tries to load the Pg.so file. On some systems, you 
can run /sbin/ldconfig -v to see a list of shared modules, or just search 
the system for the file with "locate libpq.so". If it exists but is not being 
loaded, you may need to add the directory it is in to /etc/ld.so.conf file 
and run the ldconfig command. Otherwise, you may need to add the path to 
the environment variable LD_LIBRARY_PATH.

If you get an error message like:

	perl: error while loading shared libraries:
	/usr/lib/perl5/site_perl/5.6.1/i386-linux/auto/DBD/Pg/Pg.so: undefined
	symbol: PQconnectdb

when you call DBI->connect, then your libpq.so was probably not seen at
build-time.  This should have caused 'make test' to fail; did you really
run it and look at the output? 


* Mac installation issues

Modern Mac software has a feature called Software Integrity Protection that
strips out all LD_* and DYLD_* environment variables when a program starts,
which means DBD::Pg will no compile. One solution is to use the install_name_tool
program to modify the relative paths to absolute ones. As an example:

	sudo install_name_tool -change \
	libpq.5.dylib /Library/PostgreSQL/11/lib/libpq.5.dylib \
    ~/perl5/lib/perl5/darwin-thread-multi-2level/auto/DBD/Pg/Pg.bundle


* Perl issues:

Some Linux distributions have incomplete perl installations.  If you have
compile errors like "XS_VERSION_BOOTCHECK undeclared", do:

	find .../lib/perl5 -name XSUB.h -print

If this file is not present, you need to recompile and re-install perl.


If you get a message about "use of uninitialized value in -d" when doing 
a "make install_vendor", you can work around this by adding a dummy value 
to the INSTALLVENDORBIN environment variable:

make install_vendor INSTALLVENDORBIN=/tmp
(thanks to Peter Eisentraut <peter_e at gmx.net>)


* Strawberry Perl issues:

You'll need to create a .a library from the .dll before 
running the Makefile.PL, by running pexports and dlltool
as shown below, within the C:\Program Files\PostgreSQL\8.3\bin
directory:

  C:\Windows\> C:\MinGW\bin\pexports libpq.dll > libpq.def
  C:\Windows\> C:\MinGW\bin\dlltool -dllname libpq.dll --def libpq.def
--output-lib "C:\Program
Files\PostgreSQL\12\lib\libpq.a"

pexports and dlltool are included with MinGW - Minimalist Gnu for Windows,
found here:

  https://osdn.net/projects/mingw/releases/

Once you have installed MinGW you can install pexports and dlltool as
follows:

  C:\Windows\> C:\MinGW\bin\mingw-get.exe install pexports
  C:\Windows\> C:\MinGW\bin\mingw-get.exe install dlltool

Then you'll need to set the required environment:

  set PATH=C:\PROGRA~1\PostgreSQL\8.3\bin;%PATH%
  set DBI_DSN=dbi:Pg:dbname=testdb
  set DBI_USER=*PostgreSQL username*
  set DBI_PASS=*PostgreSQL password*
  set POSTGRES_HOME=C:/PROGRA~1/PostgreSQL/8.3
  set POSTGRES_INCLUDE=C:/PROGRA~1/PostgreSQL/8.3/include
  set POSTGRES_LIB=C:/PROGRA~1/PostgreSQL/8.3/lib

Note that the username and password are the ones for PostgreSQL, NOT the 
ones for the Windows account that the PostgreSQL installer creates to run 
the service safely.

(You may wish to set these variables on the system level, by going to
Control Panel > System > Advanced tab > Environment Variables button and
adding the environment variables there.)
  
Now the Makefile.PL can be ran:

  perl Makefile.PL
  dmake
  dmake test
  dmake install


* SGI issues:

If you get segmentation faults, make sure you are using the malloc
which comes with perl when compiling perl (the default is not to).
(thanks to "David R. Noble" <drnoble at engsci.sandia.gov>)


* HP issues:

If you get error messages like:

	can't open shared library: .../lib/libpq.sl
	No such file or directory

when running the test script, try to replace the 'shared' option in the
LDDFLAGS with 'archive'.
(thanks to Dan Lauterbach <danla at dimensional.com>)


* FreeBSD issues:

If you get during "make test" the error message:

	'DBD driver has not implemented the AutoCommit attribute'

recompile the DBI module and the DBD-Pg module and disable optimization.
This error message is due to the broken optimization in gcc-2.7.2.1.


If you get compiler errors like:

	In function `XS_DBD__Pg__dr_discon_all_'
	`sv_yes' undeclared (first use in this function)

it may be because there is a 'patchlevel.h' file from another package 
(such as 'hdf') in your POSTGRES_INCLUDE dir.  The presence of this file 
prevents the compiler from finding the perl include file 
'mach/CORE/patchlevel.h'.  Do 'pg_config --includedir' to identify the 
POSTGRES_INCLUDE dir.  Rename patchlevel.h whilst you build DBD::Pg. 


* Sun issues:

If you get compile errors like:

	/usr/include/string.h:57: parse error before `]'

then you need to remove from pgsql/include/libpq-fe.h the define for
strerror, which clashes with the definition in the standard include
file.


* Win32 issues:

For installation, please see the README.win32 file.

Running DBD-Pg scripts on Win32 needs some configuration work
on the server side:

    o add a postgres user with the same name as the NT-User 
      (e.g. Administrator)
    o make sure, that your pg_hba.conf on the server is configured,
      such that a connection from another host will be accepted


* OS X issues:

You may need to add "-lssl" and "-lcrypto" to your LIB variable 
before compiling.
(thanks to <rob at cabrion dot com>)

If having problems compiling, try running:

env -i command

This trick stops 'command' from inheriting environment variables from 
the shell process, which more often than not fixes up such weird build 
errors without having to do anything else in particular.
(thanks to David Landgren <david at landgren dot net>)


* SCO issues:

If the 'make test' gives an error about a symbol not being found, 
you can correct the problem by manually running ld after the 
'make' command:

LD_RUN_PATH="/usr/local/pgsql/lib" ld -G -L/usr/local/lib Pg.o \
dbdimp.o -o blib/arch/auto/DBD/Pg/Pg.so -L/usr/local/pgsql/lib -lpq \
-L/opt/K/SKUNK2000/Gcc/2.95.2pl1/usr/local/lib/gcc-lib/i386-pc-sco3.2v5.0.5/2.95.2/ \
-lgcc

Once this is done, 'make test' succeeds properly.
(thanks to <jmore at remote-print.com>)


COPYRIGHT:
----------

	Copyright (c) 2002-2024 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


LICENSE INFORMATION:
--------------------
This module (DBD::Pg) is free software; you can redistribute it and/or modify it 
under the same terms as Perl 5.10.0. For more details, see the full text of the 
licenses in the directory LICENSES.