On Tue, Feb 28, 2023 at 11:11:30PM +0000, Imseih (AWS), Sami wrote: > I agree. We introduce the concept of a plannable statement in a > previous section and we can then make this distinction in the new > paragraph. > > I also added a link to pg_stat_statements_info since that is introduced > later on int the doc.
I have reworded the paragraph a bit to be more general so as it would not need an update once more normalization is applied to utility queries (I am going to fix the part where we mention that we use the strings for utilities, which is not the case anymore now): + <para> + Queries on which normalization can be applied may be observed with constant + values in <structname>pg_stat_statements</structname>, especially when there + is a high rate of entry deallocations. To reduce the likelihood of this + happening, consider increasing <varname>pg_stat_statements.max</varname>. + The <structname>pg_stat_statements_info</structname> view, discussed below + in <xref linkend="pgstatstatements-pg-stat-statements-info"/>, + provides statistics about entry deallocations. + </para> Are you OK with this text? -- Michael
From dd8938e4ba1b1f29d14b3fa2dc76301f42592cad Mon Sep 17 00:00:00 2001
From: Michael Paquier <mich...@paquier.xyz>
Date: Wed, 1 Mar 2023 09:05:08 +0900
Subject: [PATCH v3] doc update regarding pg_stat_statements normalization.
It is quite possible that a query text willl not normalize
(replace constants with $1, $2..) when there is a high rate
pgss_hash deallocation. This commit calls this out in docs.
---
doc/src/sgml/pgstatstatements.sgml | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index efc36da602..f1ba78c8cb 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -516,6 +516,16 @@
<structname>pg_stat_statements</structname> entry.
</para>
+ <para>
+ Queries on which normalization can be applied may be observed with constant
+ values in <structname>pg_stat_statements</structname>, especially when there
+ is a high rate of entry deallocations. To reduce the likelihood of this
+ happening, consider increasing <varname>pg_stat_statements.max</varname>.
+ The <structname>pg_stat_statements_info</structname> view, discussed below
+ in <xref linkend="pgstatstatements-pg-stat-statements-info"/>,
+ provides statistics about entry deallocations.
+ </para>
+
<para>
In some cases, queries with visibly different texts might get merged into a
single <structname>pg_stat_statements</structname> entry. Normally this will happen
--
2.39.2
signature.asc
Description: PGP signature
