These functions have been around for a while, but commits 48b5aa3 and
15afb7d were only back-patched to v16. Any objections if I apply them down
to v13 now?
--
nathan
>From 5c2fafe16a95bea32fd0808d596afb18446f69a6 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nat...@postgresql.org>
Date: Mon, 30 Jun 2025 16:21:34 -0500
Subject: [PATCH v1 1/1] Document age(xid) and mxid_age(xid).
---
doc/src/sgml/func.sgml | 31 ++++++++++++++++++++++++++++++-
1 file changed, 30 insertions(+), 1 deletion(-)
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 372cb036fde..f11c4f711d4 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -24638,6 +24638,34 @@ SELECT collation for ('foo' COLLATE "de_DE");
</thead>
<tbody>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>age</primary>
+ </indexterm>
+ <function>age</function> ( <type>xid</type> )
+ <returnvalue>integer</returnvalue>
+ </para>
+ <para>
+ Returns the number of transactions between the supplied
+ transaction id and the current transaction counter.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>mxid_age</primary>
+ </indexterm>
+ <function>mxid_age</function> ( <type>xid</type> )
+ <returnvalue>integer</returnvalue>
+ </para>
+ <para>
+ Returns the number of multixacts IDs between the supplied
+ multixact ID and the current multixacts counter.
+ </para></entry>
+ </row>
+
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
@@ -24773,7 +24801,8 @@ SELECT collation for ('foo' COLLATE "de_DE");
<para>
The internal transaction ID type <type>xid</type> is 32 bits wide and
wraps around every 4 billion transactions. However,
- the functions shown in <xref linkend="functions-pg-snapshot"/> use a
+ the functions shown in <xref linkend="functions-pg-snapshot"/>, except
+ <function>age</function> and <function>mxid_age</function>, use a
64-bit type <type>xid8</type> that does not wrap around during the life
of an installation, and can be converted to <type>xid</type> by casting if
required. The data type <type>pg_snapshot</type> stores information about
--
2.39.5 (Apple Git-154)
