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<chapter xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
version="5.0"
xml:id="module-postgresql">
<title>PostgreSQL</title>
<!-- FIXME: render nicely -->
<!-- FIXME: source can be added automatically -->
<para>
<emphasis>Source:</emphasis> <filename>modules/services/databases/postgresql.nix</filename>
</para>
<para>
<emphasis>Upstream documentation:</emphasis> <link xlink:href="http://www.postgresql.org/docs/"/>
</para>
<!-- FIXME: more stuff, like maintainer? -->
<para>
PostgreSQL is an advanced, free relational database.
<!-- MORE -->
</para>
<section xml:id="module-services-postgres-configuring">
<title>Configuring</title>
<para>
To enable PostgreSQL, add the following to your <filename>configuration.nix</filename>:
<programlisting>
<xref linkend="opt-services.postgresql.enable"/> = true;
<xref linkend="opt-services.postgresql.package"/> = pkgs.postgresql_11;
</programlisting>
Note that you are required to specify the desired version of PostgreSQL (e.g. <literal>pkgs.postgresql_11</literal>). Since upgrading your PostgreSQL version requires a database dump and reload (see below), NixOS cannot provide a default value for <xref linkend="opt-services.postgresql.package"/> such as the most recent release of PostgreSQL.
</para>
<!--
<para>After running <command>nixos-rebuild</command>, you can verify
whether PostgreSQL works by running <command>psql</command>:
<screen>
<prompt>$ </prompt>psql
psql (9.2.9)
Type "help" for help.
<prompt>alice=></prompt>
</screen>
-->
<para>
By default, PostgreSQL stores its databases in <filename>/var/lib/postgresql/$psqlSchema</filename>. You can override this using <xref linkend="opt-services.postgresql.dataDir"/>, e.g.
<programlisting>
<xref linkend="opt-services.postgresql.dataDir"/> = "/data/postgresql";
</programlisting>
</para>
</section>
<section xml:id="module-services-postgres-upgrading">
<title>Upgrading</title>
<para>
Major PostgreSQL upgrade requires PostgreSQL downtime and a few imperative steps to be called. To simplify this process, use the following NixOS module:
<programlisting>
containers.temp-pg.config.services.postgresql = {
enable = true;
package = pkgs.postgresql_12;
## set a custom new dataDir
# dataDir = "/some/data/dir";
};
environment.systemPackages =
let newpg = config.containers.temp-pg.config.services.postgresql;
in [
(pkgs.writeScriptBin "upgrade-pg-cluster" ''
set -x
export OLDDATA="${config.services.postgresql.dataDir}"
export NEWDATA="${newpg.dataDir}"
export OLDBIN="${config.services.postgresql.package}/bin"
export NEWBIN="${newpg.package}/bin"
install -d -m 0700 -o postgres -g postgres "$NEWDATA"
cd "$NEWDATA"
sudo -u postgres $NEWBIN/initdb -D "$NEWDATA"
systemctl stop postgresql # old one
sudo -u postgres $NEWBIN/pg_upgrade \
--old-datadir "$OLDDATA" --new-datadir "$NEWDATA" \
--old-bindir $OLDBIN --new-bindir $NEWBIN \
"$@"
'')
];
</programlisting>
</para>
<para>
The upgrade process is:
</para>
<orderedlist>
<listitem>
<para>
Rebuild nixos configuration with the configuration above added to your <filename>configuration.nix</filename>. Alternatively, add that into separate file and reference it in <literal>imports</literal> list.
</para>
</listitem>
<listitem>
<para>
Login as root (<literal>sudo su -</literal>)
</para>
</listitem>
<listitem>
<para>
Run <literal>upgrade-pg-cluster</literal>. It will stop old postgresql, initialize new one and migrate old one to new one. You may supply arguments like <literal>--jobs 4</literal> and <literal>--link</literal> to speedup migration process. See <link xlink:href="https://www.postgresql.org/docs/current/pgupgrade.html" /> for details.
</para>
</listitem>
<listitem>
<para>
Change postgresql package in NixOS configuration to the one you were upgrading to, and change <literal>dataDir</literal> to the one you have migrated to. Rebuild NixOS. This should start new postgres using upgraded data directory.
</para>
</listitem>
<listitem>
<para>
After upgrade you may want to <literal>ANALYZE</literal> new db.
</para>
</listitem>
</orderedlist>
</section>
<section xml:id="module-services-postgres-options">
<title>Options</title>
<para>
A complete list of options for the PostgreSQL module may be found <link linkend="opt-services.postgresql.enable">here</link>.
</para>
</section>
<section xml:id="module-services-postgres-plugins">
<title>Plugins</title>
<para>
Plugins collection for each PostgreSQL version can be accessed with <literal>.pkgs</literal>. For example, for <literal>pkgs.postgresql_11</literal> package, its plugin collection is accessed by <literal>pkgs.postgresql_11.pkgs</literal>:
<screen>
<prompt>$ </prompt>nix repl '<nixpkgs>'
Loading '<nixpkgs>'...
Added 10574 variables.
<prompt>nix-repl> </prompt>postgresql_11.pkgs.<TAB><TAB>
postgresql_11.pkgs.cstore_fdw postgresql_11.pkgs.pg_repack
postgresql_11.pkgs.pg_auto_failover postgresql_11.pkgs.pg_safeupdate
postgresql_11.pkgs.pg_bigm postgresql_11.pkgs.pg_similarity
postgresql_11.pkgs.pg_cron postgresql_11.pkgs.pg_topn
postgresql_11.pkgs.pg_hll postgresql_11.pkgs.pgjwt
postgresql_11.pkgs.pg_partman postgresql_11.pkgs.pgroonga
...
</screen>
</para>
<para>
To add plugins via NixOS configuration, set <literal>services.postgresql.extraPlugins</literal>:
<programlisting>
<xref linkend="opt-services.postgresql.package"/> = pkgs.postgresql_11;
<xref linkend="opt-services.postgresql.extraPlugins"/> = with pkgs.postgresql_11.pkgs; [
pg_repack
postgis
];
</programlisting>
</para>
<para>
You can build custom PostgreSQL-with-plugins (to be used outside of NixOS) using function <literal>.withPackages</literal>. For example, creating a custom PostgreSQL package in an overlay can look like:
<programlisting>
self: super: {
postgresql_custom = self.postgresql_11.withPackages (ps: [
ps.pg_repack
ps.postgis
]);
}
</programlisting>
</para>
<para>
Here's a recipe on how to override a particular plugin through an overlay:
<programlisting>
self: super: {
postgresql_11 = super.postgresql_11.override { this = self.postgresql_11; } // {
pkgs = super.postgresql_11.pkgs // {
pg_repack = super.postgresql_11.pkgs.pg_repack.overrideAttrs (_: {
name = "pg_repack-v20181024";
src = self.fetchzip {
url = "https://github.com/reorg/pg_repack/archive/923fa2f3c709a506e111cc963034bf2fd127aa00.tar.gz";
sha256 = "17k6hq9xaax87yz79j773qyigm4fwk8z4zh5cyp6z0sxnwfqxxw5";
};
});
};
};
}
</programlisting>
</para>
</section>
</chapter>
|