v34-0005-Consolidate-attribute-syscache-lookups-into-one-.patch

From b0f1797617b8c33ecad93c83089b1cee27b1072f Mon Sep 17 00:00:00 2001
From: Corey Huinker <corey.huinker@gmail.com>
Date: Thu, 14 Nov 2024 03:53:33 -0500
Subject: [PATCH v34 05/11] Consolidate attribute syscache lookups into one
 call by name.

Previously we were doing one lookup by attname and one lookup by attnum,
which seems wasteful.
---
 src/backend/statistics/attribute_stats.c | 55 +++++++++++-------------
 1 file changed, 24 insertions(+), 31 deletions(-)

diff --git a/src/backend/statistics/attribute_stats.c b/src/backend/statistics/attribute_stats.c
index b97ba7b0c0..6393783f8e 100644
--- a/src/backend/statistics/attribute_stats.c
+++ b/src/backend/statistics/attribute_stats.c
@@ -78,8 +78,8 @@ static struct StatsArgInfo attarginfo[] =
 
 static bool attribute_statistics_update(FunctionCallInfo fcinfo, int elevel);
 static Node *get_attr_expr(Relation rel, int attnum);
-static void get_attr_stat_type(Oid reloid, AttrNumber attnum, int elevel,
-							   Oid *atttypid, int32 *atttypmod,
+static void get_attr_stat_type(Oid reloid, Name attname, int elevel,
+							   AttrNumber *attnum, Oid *atttypid, int32 *atttypmod,
 							   char *atttyptype, Oid *atttypcoll,
 							   Oid *eq_opr, Oid *lt_opr);
 static bool get_elem_stat_type(Oid atttypid, char atttyptype, int elevel,
@@ -166,23 +166,16 @@ attribute_statistics_update(FunctionCallInfo fcinfo, int elevel)
 
 	stats_check_required_arg(fcinfo, attarginfo, ATTNAME_ARG);
 	attname = PG_GETARG_NAME(ATTNAME_ARG);
-	attnum = get_attnum(reloid, NameStr(*attname));
-
-	if (attnum < 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot modify statistics on system column \"%s\"",
-						NameStr(*attname))));
-
-	if (attnum == InvalidAttrNumber)
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_COLUMN),
-				 errmsg("column \"%s\" of relation \"%s\" does not exist",
-						NameStr(*attname), get_rel_name(reloid))));
 
 	stats_check_required_arg(fcinfo, attarginfo, INHERITED_ARG);
 	inherited = PG_GETARG_BOOL(INHERITED_ARG);
 
+	/* derive type information from attribute */
+	get_attr_stat_type(reloid, attname, elevel,
+					   &attnum, &atttypid, &atttypmod,
+					   &atttyptype, &atttypcoll,
+					   &eq_opr, &lt_opr);
+
 	/*
 	 * Check argument sanity. If some arguments are unusable, emit at elevel
 	 * and set the corresponding argument to NULL in fcinfo.
@@ -232,12 +225,6 @@ attribute_statistics_update(FunctionCallInfo fcinfo, int elevel)
 		result = false;
 	}
 
-	/* derive information from attribute */
-	get_attr_stat_type(reloid, attnum, elevel,
-					   &atttypid, &atttypmod,
-					   &atttyptype, &atttypcoll,
-					   &eq_opr, &lt_opr);
-
 	/* if needed, derive element type */
 	if (do_mcelem || do_dechist)
 	{
@@ -503,8 +490,8 @@ get_attr_expr(Relation rel, int attnum)
  * Derive type information from the attribute.
  */
 static void
-get_attr_stat_type(Oid reloid, AttrNumber attnum, int elevel,
-				   Oid *atttypid, int32 *atttypmod,
+get_attr_stat_type(Oid reloid, Name attname, int elevel,
+				   AttrNumber *attnum, Oid *atttypid, int32 *atttypmod,
 				   char *atttyptype, Oid *atttypcoll,
 				   Oid *eq_opr, Oid *lt_opr)
 {
@@ -514,24 +501,30 @@ get_attr_stat_type(Oid reloid, AttrNumber attnum, int elevel,
 	Node	   *expr;
 	TypeCacheEntry *typcache;
 
-	atup = SearchSysCache2(ATTNUM, ObjectIdGetDatum(reloid),
-						   Int16GetDatum(attnum));
+	atup = SearchSysCacheAttName(reloid, NameStr(*attname));
 
-	/* Attribute not found */
+	/* Attribute not found or is dropped */
 	if (!HeapTupleIsValid(atup))
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_COLUMN),
-				 errmsg("attribute %d of relation \"%s\" does not exist",
-						attnum, RelationGetRelationName(rel))));
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						NameStr(*attname), get_rel_name(reloid))));
 
 	attr = (Form_pg_attribute) GETSTRUCT(atup);
 
-	if (attr->attisdropped)
+	if (attr->attnum < 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot modify statistics on system column \"%s\"",
+						NameStr(*attname))));
+
+	if (attr->attnum == InvalidAttrNumber)
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_COLUMN),
-				 errmsg("attribute %d of relation \"%s\" does not exist",
-						attnum, RelationGetRelationName(rel))));
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						NameStr(*attname), get_rel_name(reloid))));
 
+	*attnum = attr->attnum;
 	expr = get_attr_expr(rel, attr->attnum);
 
 	/*
-- 
2.47.1