On 2021-Apr-23, Justin Pryzby wrote:
> On Thu, Apr 22, 2021 at 12:43:46PM -0500, Justin Pryzby wrote:
> >
> > I think that should probably have been written down somewhere other than for
> > the manual ANALYZE command, but in any case it seems to be outdated now.
>
> Starting with this
Agreed, we need some more docs here. I lightly edited yours and ended
up with this -- mostly I think partitioned tables should not be in the
same paragraph as legacy inheritance because the behavior is different
enough (partitioned tables are not analyzed twice).
I'll give a deeper look tomorrow to see if other places also need edits.
Thanks
--
Álvaro Herrera Valdivia, Chile
diff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgml
index 89ff58338e..ddd6c3ff3e 100644
--- a/doc/src/sgml/perform.sgml
+++ b/doc/src/sgml/perform.sgml
@@ -1767,7 +1767,8 @@ SELECT * FROM x, y, a, b, c WHERE something AND somethingelse;
<para>
Whenever you have significantly altered the distribution of data
within a table, running <link linkend="sql-analyze"><command>ANALYZE</command></link> is strongly recommended. This
- includes bulk loading large amounts of data into the table. Running
+ includes bulk loading large amounts of data into the table as well as
+ attaching, detaching or dropping partitions. Running
<command>ANALYZE</command> (or <command>VACUUM ANALYZE</command>)
ensures that the planner has up-to-date statistics about the
table. With no statistics or obsolete statistics, the planner might
diff --git a/doc/src/sgml/ref/analyze.sgml b/doc/src/sgml/ref/analyze.sgml
index c8fcebc161..9d5e2a9626 100644
--- a/doc/src/sgml/ref/analyze.sgml
+++ b/doc/src/sgml/ref/analyze.sgml
@@ -250,7 +250,17 @@ ANALYZE [ VERBOSE ] [ <replaceable class="parameter">table_and_columns</replacea
</para>
<para>
- If the table being analyzed has one or more children,
+ If the table being analyzed is partitioned, <command>ANALYZE</command>
+ will gather statistics by scanning all of its partitions.
+ The autovacuum daemon counts inserts and updates in the partitions
+ to determine if auto-analyze is needed. However, adding or
+ removing partitions does not affect the autovacuum daemon decisions,
+ so triggering a manual <command>ANALYZE</command> is recommended when
+ they occur.
+ </para>
+
+ <para>
+ If the table being analyzed has one or more legacy inheritance children,
<command>ANALYZE</command> will gather statistics twice: once on the
rows of the parent table only, and a second time on the rows of the
parent table with all of its children. This second set of statistics
@@ -263,7 +273,7 @@ ANALYZE [ VERBOSE ] [ <replaceable class="parameter">table_and_columns</replacea
</para>
<para>
- If any of the child tables are foreign tables whose foreign data wrappers
+ If any of the child tables or partitions are foreign tables whose foreign data wrappers
do not support <command>ANALYZE</command>, those child tables are ignored while
gathering inheritance statistics.
</para>
diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
index 93ea937ac8..474f18c73f 100644
--- a/doc/src/sgml/ref/pg_restore.sgml
+++ b/doc/src/sgml/ref/pg_restore.sgml
@@ -922,8 +922,10 @@ CREATE DATABASE foo WITH TEMPLATE template0;
<para>
Once restored, it is wise to run <command>ANALYZE</command> on each
- restored table so the optimizer has useful statistics; see
- <xref linkend="vacuum-for-statistics"/> and
+ restored table so the optimizer has useful statistics.
+ If the table is a partition or an inheritance child, it may also be useful
+ to analyze the parent table.
+ See <xref linkend="vacuum-for-statistics"/> and
<xref linkend="autovacuum"/> for more information.
</para>
