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<appendix id="external-projects">

<title>External Projects</title>

<title>PgFoundry andExternal Projects</title>

<para>

<productname>PostgreSQL</productname> is a complex software project,

and managingit is difficult. We have found that many

and managingthe project is difficult. We have found that many

enhancements to <productname>PostgreSQL</productname> can be more

efficiently developed separately from the core project. Separate

projects can

have their own developer teams, email lists, bug tracking,

and release schedules. While their independence makes

development easier, it makes users' jobs harder. They have to hunt

around looking for database enhancements to meet their needs.

This section describes some of the more popular externally

developed enhancements and guides you on how to find them.

efficiently developed separately from the core project.

</para>

<para>

To help our community with the development of their external projects,

we have created the <ulink url="http://www.pgfoundry.org/">PgFoundry</ulink>.

<ulink url="http://www.pgfoundry.org/">PgFoundry</ulink> is built using the

GForge software project and is similar to SourceForge in its feature set. If

you have a PostgreSQL related Open Source project that you would like to

develop and need project management resources such as mailing lists, forums,

bug tracking, and CVS, please feel free to create a new project.

</para>

<para>

Many <productname>PostgreSQL</productname>-related projects are

hosted at either

<ulink url="http://gborg.postgresql.org"><productname>GBorg</></ulink>

or <ulink url="http://pgfoundry.org"><productname>pgFoundry</></ulink>.

There are other <productname>PostgreSQL</productname>-related projects that are hosted

elsewhere, but you will have to do an Internet search to find them.

Secondly, many <productname>PostgreSQL</productname>-related projects are

still hosted at <ulink url="http://gborg.postgresql.org"><productname>GBorg</></ulink>.

GBorg is the original external community developer site, and while it is

currently closed to new projects in favor of PgFoundry, it still contains

many active and relevant projects. There are other popular <productname>PostgreSQL</productname>

related projects that are hosted independently as well at other community

sites such as <ulink url="http://www.sf.net">SourceForge</ulink>. You should

google if you don't find the project you are looking for.

</para>

<sect1 id="external-interfaces">

<para>

<productname>PostgreSQL</productname> includes very few interfaces

with the base distribution. <application>libpq</> is packaged because

it is the primary <application>C</> interface and many other

interfaces are built on top of it. <application>ecpg</> is packaged

because it is tied to the server-side grammar so is very dependent

on the database version. All the other interfaces are independent

projects and must be installed separately.

it is the primary dependecy of most interfaces available to PostgreSQL.

We also package <application>ecpg</> because it is tied to the

server-side grammar. All other interfaces, such as PHP, Perl, Python,

and Ruby, are external projects.

</para>

<para>

<listitem>

<para>

This is the most common interface for <application>Windows</>

applications.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>pgjdbc</term>

<listitem>

<para>

A <application>JDBC</> interface.

applications. <ulink url="http://odbc.postgresql.org/">Website.</ulink>

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>Npgsql</term>

<term>ODBCng</term>

<listitem>

<para>

<application>.Net</> interfaceformore recent

<application>Windows</> applications.

Another ODBC driverforPostgreSQL.

<ulink url="http://projects.commandprompt.com/public/odbcng/">Website.</ulink>

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>libpqxx</term>

<term>pgjdbc</term>

<listitem>

<para>

A newer <application>C++</> interface.

A <application>JDBC</> interface.

<ulink url="http://jdbc.postgresql.org/">Website.</ulink>

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>libpq++</term>

<term>Npgsql</term>

<listitem>

<para>

An older <application>C++</> interface.

<application>.Net</> interface for more recent <application>mono/C#</> applications.

<ulink url="http://pgfoundry.org/projects/npgsql/">Website.</ulink>

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>pgperl</term>

<term>libpqxx</term>

<listitem>

<para>

A <application>Perl</> interface with an <acronym>API</> similar

Anewer<application>C++</> interface.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>DBD-Pg</term>

<term>DBD::Pg</term>

<listitem>

<para>

A <application>Perl</>interface that uses the

<acronym>DBD</>-standard <application>API</>.

A <application>Perl</>DBI driver for PostgreSQL.

<ulink url="http://search.cpan.org/dist/DBD-Pg/">Website.</ulink>

</para>

</listitem>

</varlistentry>

<listitem>

<para>

A newer version of the <application>Tcl</> interface.

<ulink url="http://gborg.postgresql.org/project/pgtclng/projdisplay.php">Website.</ulink>

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>pgtcl</term>

<listitem>

<para>

The original version of the <application>Tcl</> interface.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>PyGreSQL</term>

<term>Pyscopg</term>

<listitem>

<para>

A <application>Python</> interface library.

A <application>Python</> interface library that is DB API 2.0 compliant.

<ulink url="http://www.initd.org/">Website.</ulink>

</para>

</listitem>

</varlistentry>

</variablelist>

All of these can be found at

<ulink url="http://gborg.postgresql.org"><productname>GBorg</></ulink>

or <ulink url="http://pgfoundry.org"><productname>pgFoundry</></ulink>.

</para>

</sect1>

<para>

There are several administration tools available for

<productname>PostgreSQL</>. The most popular is

<application>pgAdmin</>, and there are several commercially

available ones.

<application><ulink url="http://www.pgadmin.org/">pgAdmin III</ulink></>,

and there are several commerciallyavailable ones as well.

</para>

</sect1>

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<chapter id="maintenance">

<title>Routine Database Maintenance Tasks</title>

<primary>maintenance</primary>

</indexterm>

<indexterm zone="maintenance">

<primary>Routine maintenance</primary>

</indexterm>

<para>

There are a few routine maintenance chores that must be performed on

a regular basis to keep a <productname>PostgreSQL</productname>

server running smoothly. The tasks discussed here are repetitive

in nature and can easily be automated using standard Unix tools such

as <application>cron</application> scripts. But it is the database

administrator's responsibility to set up appropriate scripts, and to

check that they execute successfully.

PostgreSQL, like any database software, requires that certain tasks

be performed regularly to achieve optimum performance. The tasks

discussed here are <emphasis>required</emphasis>, but they

are repetitive in nature and can easily be automated using standard

Unix tools such as <application>cron</application> scripts.

</para>

<para>

One obvious maintenance task is creation of backup copies of the data on a

regular schedule. Without a recent backup, you have no chance of recovery

after a catastrophe (disk failure, fire, mistakenly dropping a critical

table, etc.). The backup and recovery mechanisms available in

<productname>PostgreSQL</productname> are discussed at length in

<xref linkend="backup">.

<productname>PostgreSQL</productname> is low-maintenance compared

to other database management systems. It is also fairly easy, provided

you read the documentation.

</para>

<para>

The other main category of maintenance task is periodic <quote>vacuuming</>

of the database. This activity is discussed in

<xref linkend="routine-vacuuming">.

There are three tasks that <emphasis>must</emphasis> be performed on

a periodic basis. The first is backups. If you do not have a current backup

and your system experiences a catastrophic failure, you will lose your data.

You can read further about backups procedures in <xref linkend="backup">.

The second is vacuum which is discussed in <xref linkend="routine-vacuuming">.

The third is to update the planner statistics using the analyze command as

discussed in <xref linkend="vacuum-for-statistics">.

</para>

<para>

Something else thatmight need periodic attention is log file management.

Another task thatmay need periodic attention is log file management.

This is discussed in <xref linkend="logfile-maintenance">.

</para>

<para>

<productname>PostgreSQL</productname> is low-maintenance compared

to some other database management systems. Nonetheless,

appropriate attention to these tasks will go far towards ensuring a

pleasant and productive experience with the system.

</para>

<sect1 id="routine-vacuuming">

<title>Routine Vacuuming</title>

<para>

<productname>PostgreSQL</productname>'s <command>VACUUM</> command

must be run on a regular basis for several reasons:

<emphasis>must</emphasis> be run on a regular basis for several reasons:

<orderedlist>

<listitem>

<simpara>To recover disk space occupied by updated or deleted

<simpara>To recoveror reusedisk space occupied by updated or deleted

rows.</simpara>

</listitem>

</para>

<para>

The standard form of <command>VACUUM</> can run in parallel with

normal database operations (SELECTs, INSERTs, UPDATEs, DELETEs, but not

changes to table definitions).

Beginning in <productname>PostgreSQL</productname> 8.0, there are

configuration parameters that can be adjusted to further reduce the

The standard form of <command>VACUUM</> does not intefere with production

database operations. Items such as SELECTS, INSERTS, UPDATES and DELETES

will continue to function as normal, though you will not be able to modify the

definition (Such as ALTER TABLE ADD COLUMN) of a table while it is being vacuumed.

The release of <productname>PostgreSQL</productname> 8.0, introduced new

configuration parameters to further reduce the potentially negative

performance impact of background vacuuming. See

<xref linkend="runtime-config-resource-vacuum-cost">.

</para>

</para>

<para>

If you have a table whose contents are deleted on a periodic

basis, consider doing it with <command>TRUNCATE</command> rather

than using <command>DELETE</command> followed by

If you have a table whoseentirecontents are deleted on a periodic

basis, consider doing it withthe<command>TRUNCATE</command> rather

than usingthe<command>DELETE</command> followed by

<command>VACUUM</command>. <command>TRUNCATE</command> removes the

entire content of the table immediately, without requiring a

subsequent <command>VACUUM</command> or <command>VACUUM