cache lookup failed for statistics object 123

From 6dec09300e4ad6cc7977acbfee9db7087420a9b5 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Wed, 5 May 2021 04:29:00 -0500
Subject: [PATCH 1/3] Return NULL rather than elog(ERROR) for sql-callable
 function

---
 src/backend/utils/adt/ruleutils.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 0a4fa93d01..881e8ec03d 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -1759,9 +1759,9 @@ pg_get_statisticsobjdef_expressions(PG_FUNCTION_ARGS)
 	statexttup = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(statextid));
 
 	if (!HeapTupleIsValid(statexttup))
-		elog(ERROR, "cache lookup failed for statistics object %u", statextid);
+		PG_RETURN_NULL();
 
-	/* has the statistics expressions? */
+	/* Does the stats object have expressions? */
 	has_exprs = !heap_attisnull(statexttup, Anum_pg_statistic_ext_stxexprs, NULL);
 
 	/* no expressions? we're done */
-- 
2.17.0

From ede54e64cf5e2249fe6910d6f2c0de177a0edb9b Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Tue, 27 Apr 2021 07:57:50 -0500
Subject: [PATCH 2/3] Comment typos: extended stats a4d75c86b and 518442c7f

---
 src/backend/parser/parse_utilcmd.c      | 2 +-
 src/backend/statistics/extended_stats.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 9dd30370da..eb9e63f4a8 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -1943,7 +1943,7 @@ generateClonedExtStatsStmt(RangeVar *heapRel, Oid heapRelid,
 	 * simply append them after simple column references.
 	 *
 	 * XXX Some places during build/estimation treat expressions as if they
-	 * are before atttibutes, but for the CREATE command that's entirely
+	 * are before attributes, but for the CREATE command that's entirely
 	 * irrelevant.
 	 */
 	datum = SysCacheGetAttr(STATEXTOID, ht_stats,
diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c
index 7e11cb9d5f..5e53783ea6 100644
--- a/src/backend/statistics/extended_stats.c
+++ b/src/backend/statistics/extended_stats.c
@@ -1796,7 +1796,7 @@ statext_mcv_clauselist_selectivity(PlannerInfo *root, List *clauses, int varReli
 				continue;
 
 			/*
-			 * Now we know the clause is compatible (we have either atttnums
+			 * Now we know the clause is compatible (we have either attnums
 			 * or expressions extracted from it), and was not estimated yet.
 			 */
 
-- 
2.17.0

From e64e4b3d206d76ed8bbd5345798e0d35958759bd Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Fri, 23 Apr 2021 09:15:40 -0500
Subject: [PATCH 3/3] Mention statistics objects

Previously mentioned at 20210423025012.GI7256@telsasoft.com
---
 doc/src/sgml/maintenance.sgml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
index ee6113926a..de7fd75e1c 100644
--- a/doc/src/sgml/maintenance.sgml
+++ b/doc/src/sgml/maintenance.sgml
@@ -330,7 +330,8 @@
 
     <para>
      Also, by default there is limited information available about
-     the selectivity of functions.  However, if you create an expression
+     the selectivity of functions.  However, if you create a statistics
+     object or an expression
      index that uses a function call, useful statistics will be
      gathered about the function, which can greatly improve query
      plans that use the expression index.
-- 
2.17.0