v2-0001-Improve-error-message-for-database-object-stats-m.patch

From 0d8711ff4a52a81c337c157177c423ce65bb3c20 Mon Sep 17 00:00:00 2001
From: Fujii Masao <fujii@postgresql.org>
Date: Sat, 26 Oct 2024 01:09:46 +0900
Subject: [PATCH v2] Improve error message for database object stats
 manipulation functions.

Previously, database object statistics manipulation functions like
pg_set_relation_stats() reported unclear error and hint messages
when executed during recovery. These messages were "internal",
making it difficult for users to understand the issue:

  ERROR:  cannot acquire lock mode ShareUpdateExclusiveLock on database objects while recovery is in progress
  HINT:  Only RowExclusiveLock or less can be acquired on database objects during recovery.

This commit updates the error handling so that, if these functions
are called during recovery, they produce clearer messages:

  ERROR:  recovery is in progress
  HINT:  Statistics cannot be modified during recovery.

The related documentation has also been updated to explicitly
clarify that these functions are not available during recovery.

Author: Fujii Masao
Reviewed-by: Heikki Linnakangas, Maxim Orlov
Discussion: https://postgr.es/m/6d313829-5f56-4a28-ae4b-bd01bf1ae791@oss.nttdata.com
---
 doc/src/sgml/func.sgml                   |  1 +
 src/backend/statistics/attribute_stats.c | 12 ++++++++++++
 src/backend/statistics/relation_stats.c  |  6 ++++++
 3 files changed, 19 insertions(+)

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 73979f20ff..1a0b85bb4d 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -30029,6 +30029,7 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset
    <para>
     <xref linkend="functions-admin-statsmod"/> lists functions used to
     manipulate statistics.
+    These functions cannot be executed during recovery.
     <warning>
      <para>
       Changes made by these statistics manipulation functions are likely to be
diff --git a/src/backend/statistics/attribute_stats.c b/src/backend/statistics/attribute_stats.c
index 4ae0722b78..686f2e639c 100644
--- a/src/backend/statistics/attribute_stats.c
+++ b/src/backend/statistics/attribute_stats.c
@@ -155,6 +155,12 @@ attribute_statistics_update(FunctionCallInfo fcinfo, int elevel)
 	stats_check_required_arg(fcinfo, attarginfo, ATTRELATION_ARG);
 	reloid = PG_GETARG_OID(ATTRELATION_ARG);
 
+	if (RecoveryInProgress())
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("recovery is in progress"),
+				 errhint("Statistics cannot be modified during recovery.")));
+
 	/* lock before looking up attribute */
 	stats_lock_check_privileges(reloid);
 
@@ -865,6 +871,12 @@ pg_clear_attribute_stats(PG_FUNCTION_ARGS)
 	stats_check_required_arg(fcinfo, attarginfo, ATTRELATION_ARG);
 	reloid = PG_GETARG_OID(ATTRELATION_ARG);
 
+	if (RecoveryInProgress())
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("recovery is in progress"),
+				 errhint("Statistics cannot be modified during recovery.")));
+
 	stats_lock_check_privileges(reloid);
 
 	stats_check_required_arg(fcinfo, attarginfo, ATTNAME_ARG);
diff --git a/src/backend/statistics/relation_stats.c b/src/backend/statistics/relation_stats.c
index ed5dea2e05..e619d5cf5b 100644
--- a/src/backend/statistics/relation_stats.c
+++ b/src/backend/statistics/relation_stats.c
@@ -72,6 +72,12 @@ relation_statistics_update(FunctionCallInfo fcinfo, int elevel)
 	stats_check_required_arg(fcinfo, relarginfo, RELATION_ARG);
 	reloid = PG_GETARG_OID(RELATION_ARG);
 
+	if (RecoveryInProgress())
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("recovery is in progress"),
+				 errhint("Statistics cannot be modified during recovery.")));
+
 	stats_lock_check_privileges(reloid);
 
 	/*
-- 
2.47.0