From 0de7128deb2b29cf3359211e102473b4080b10d0 Mon Sep 17 00:00:00 2001
From: Jan Tojnar <jtojnar@gmail.com>
Date: Wed, 26 Oct 2022 15:05:13 +0200
Subject: [PATCH 1/3] doc/nixos/postgress: Streamline upgrade script

We already need to set the package so no need to manually copy the schema version.
---
 nixos/modules/services/databases/postgresql.xml | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/nixos/modules/services/databases/postgresql.xml b/nixos/modules/services/databases/postgresql.xml
index 0ca9f3faed21..d113f5ed1c45 100644
--- a/nixos/modules/services/databases/postgresql.xml
+++ b/nixos/modules/services/databases/postgresql.xml
@@ -72,16 +72,17 @@ Type "help" for help.
 { config, pkgs, ... }:
 {
   <xref linkend="opt-environment.systemPackages" /> = [
-    (pkgs.writeScriptBin "upgrade-pg-cluster" ''
+    (let
+      # XXX specify the postgresql package you'd like to upgrade to.
+      newPostgres = pkgs.postgresql_13;
+    in pkgs.writeScriptBin "upgrade-pg-cluster" ''
       set -eux
       # XXX it's perhaps advisable to stop all services that depend on postgresql
       systemctl stop postgresql
 
-      # XXX replace `&lt;new version&gt;` with the psqlSchema here
-      export NEWDATA="/var/lib/postgresql/&lt;new version&gt;"
+      export NEWDATA="/var/lib/postgresql/${newPostgres.psqlSchema}"
 
-      # XXX specify the postgresql package you'd like to upgrade to
-      export NEWBIN="${pkgs.postgresql_13}/bin"
+      export NEWBIN="${newPostgres}/bin"
 
       export OLDDATA="${config.<xref linkend="opt-services.postgresql.dataDir"/>}"
       export OLDBIN="${config.<xref linkend="opt-services.postgresql.package"/>}/bin"

From e598636243c6080420153ab24af472a610e7a4ee Mon Sep 17 00:00:00 2001
From: Jan Tojnar <jtojnar@gmail.com>
Date: Wed, 26 Oct 2022 14:57:30 +0200
Subject: [PATCH 2/3] doc/nixos/postgress: Mention extensions in upgrading

This is easy to miss and can lead to annoying failures.
---
 nixos/modules/services/databases/postgresql.xml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/nixos/modules/services/databases/postgresql.xml b/nixos/modules/services/databases/postgresql.xml
index d113f5ed1c45..a442008db8a0 100644
--- a/nixos/modules/services/databases/postgresql.xml
+++ b/nixos/modules/services/databases/postgresql.xml
@@ -74,7 +74,10 @@ Type "help" for help.
   <xref linkend="opt-environment.systemPackages" /> = [
     (let
       # XXX specify the postgresql package you'd like to upgrade to.
-      newPostgres = pkgs.postgresql_13;
+      # Do not forget to list the extensions you need.
+      newPostgres = pkgs.postgresql_13.withPackages (pp: [
+        # pp.plv8
+      ]);
     in pkgs.writeScriptBin "upgrade-pg-cluster" ''
       set -eux
       # XXX it's perhaps advisable to stop all services that depend on postgresql

From 04e85da1c07995d156f2e86d6c012c5fd15beaa9 Mon Sep 17 00:00:00 2001
From: Jan Tojnar <jtojnar@gmail.com>
Date: Wed, 26 Oct 2022 15:21:06 +0200
Subject: [PATCH 3/3] doc/nixos/postgress: Mention extensions in upgrading

analyze_new_cluster script is not available in PostgreSQL 14+:

https://github.com/postgres/postgres/commit/8f113698b63b15a4e0a4b15d3ee37238c1d1821d
---
 .../modules/services/databases/postgresql.xml | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/nixos/modules/services/databases/postgresql.xml b/nixos/modules/services/databases/postgresql.xml
index a442008db8a0..e48c578e6ce6 100644
--- a/nixos/modules/services/databases/postgresql.xml
+++ b/nixos/modules/services/databases/postgresql.xml
@@ -131,12 +131,25 @@ Type "help" for help.
    </listitem>
    <listitem>
     <para>
-     After the upgrade it's advisable to analyze the new cluster (as <literal>su -l postgres</literal> in the
-     <xref linkend="opt-services.postgresql.dataDir" />, in this example <filename>/var/lib/postgresql/13</filename>):
+     After the upgrade it's advisable to analyze the new cluster.
+    </para>
+    <itemizedlist>
+     <listitem>
+      <para>
+       For PostgreSQL ≥ 14, use the <literal>vacuumdb</literal> command printed by the upgrades script.
+      </para>
+     </listitem>
+     <listitem>
+       <para>
+        For PostgreSQL &lt; 14, run (as <literal>su -l postgres</literal> in the <xref linkend="opt-services.postgresql.dataDir" />, in this example <filename>/var/lib/postgresql/13</filename>):
 <programlisting>
 <prompt>$ </prompt>./analyze_new_cluster.sh
 </programlisting>
-     <warning><para>The next step removes the old state-directory!</para></warning>
+       </para>
+     </listitem>
+    </itemizedlist>
+    <para>
+      <warning><para>The next step removes the old state-directory!</para></warning>
 <programlisting>
 <prompt>$ </prompt>./delete_old_cluster.sh
 </programlisting>