From fbd4321fd5b4400fbbf356d686af6ad6d3208c66 Mon Sep 17 00:00:00 2001
From: Alexander Korotkov <akorotkov@postgresql.org>
Date: Thu, 23 May 2024 02:22:40 +0300
Subject: Don't copy extended statistics during MERGE/SPLIT partition
 operations

When MERGE/SPLIT created new partitions, it was cloning the extended
statistics of the parent table.

However, extended stats on partitioned tables don't behave like
indexes on partitioned tables (which exist only to create physical
indexes on child tables).  Rather, extended stats on a parent 1) cause
extended stats to be collected and computed across the whole partition
hierarchy, and 2) do not cause extended stats to be computed for the
individual partitions.

"CREATE TABLE ... PARTITION OF" command doesn't copy extended
statistics.  This commit makes createPartitionTable() behave
consistently.

Reported-by: Justin Pryzby
Discussion: https://postgr.es/m/ZiJW1g2nbQs9ekwK%40pryzbyj2023
Author: Alexander Korotkov, Justin Pryzby
---
 doc/src/sgml/ref/alter_table.sgml | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 5d352abf991..c062a36880d 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -1154,9 +1154,12 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
      </para>
      <para>
       The new partitions will be created the same as tables created with the
-      SQL command <literal>CREATE TABLE <replaceable class="parameter">partition_nameN</replaceable> (LIKE <replaceable class="parameter">name</replaceable> INCLUDING ALL EXCLUDING INDEXES EXCLUDING IDENTITY)</literal>.
+      SQL command <literal>CREATE TABLE <replaceable class="parameter">partition_nameN</replaceable> (LIKE <replaceable class="parameter">name</replaceable> INCLUDING ALL EXCLUDING INDEXES EXCLUDING IDENTITY EXCLUDING STATISTICS)</literal>.
       The indexes and identity are created later, after moving the data
       into the new partitions.
+      Extended statistics aren't copied from the parent table, for consistency with
+      <command>CREATE TABLE PARTITION OF</command>.
+
       New partitions will have the same table access method as the parent.
       If the parent table is persistent then new partitions are created
       persistent.  If the parent table is temporary then new partitions
@@ -1224,9 +1227,11 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
      </para>
      <para>
       The new partition will be created the same as a table created with the
-      SQL command <literal>CREATE TABLE <replaceable class="parameter">partition_name</replaceable> (LIKE <replaceable class="parameter">name</replaceable> INCLUDING ALL EXCLUDING INDEXES EXCLUDING IDENTITY)</literal>.
+      SQL command <literal>CREATE TABLE <replaceable class="parameter">partition_name</replaceable> (LIKE <replaceable class="parameter">name</replaceable> INCLUDING ALL EXCLUDING INDEXES EXCLUDING IDENTITY EXCLUDING STATISTICS)</literal>.
       The indexes and identity are created later, after moving the data
       into the new partition.
+      Extended statistics aren't copied from the parent table, for consistency with
+      <command>CREATE TABLE PARTITION OF</command>.
       The new partition will have the same table access method as the parent.
       If the parent table is persistent then the new partition is created
       persistent.  If the parent table is temporary then the new partition
-- 
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