From f714fa6fdb860c89b3bb8bc54465a43e24bf9496 Mon Sep 17 00:00:00 2001
From: John Naylor <john.naylor@postgresql.org>
Date: Tue, 9 Aug 2022 12:37:22 +0700
Subject: [PATCH v11 3/4] Use optimized linear search for testing if relations
 have a syscache

XXX: not for commit just yet
---
 src/backend/utils/cache/syscache.c | 69 +++---------------------------
 1 file changed, 5 insertions(+), 64 deletions(-)

diff --git a/src/backend/utils/cache/syscache.c b/src/backend/utils/cache/syscache.c
index 1912b12146..d354161c54 100644
--- a/src/backend/utils/cache/syscache.c
+++ b/src/backend/utils/cache/syscache.c
@@ -76,6 +76,7 @@
 #include "catalog/pg_type.h"
 #include "catalog/pg_user_mapping.h"
 #include "lib/qunique.h"
+#include "port/pg_lfind.h"
 #include "utils/catcache.h"
 #include "utils/rel.h"
 #include "utils/syscache.h"
@@ -1044,16 +1045,14 @@ static CatCache *SysCache[SysCacheSize];
 
 static bool CacheInitialized = false;
 
-/* Sorted array of OIDs of tables that have caches on them */
+/* Array of OIDs of tables that have caches on them */
 static Oid	SysCacheRelationOid[SysCacheSize];
 static int	SysCacheRelationOidSize;
 
-/* Sorted array of OIDs of tables and indexes used by caches */
+/* Array of OIDs of tables and indexes used by caches */
 static Oid	SysCacheSupportingRelOid[SysCacheSize * 2];
 static int	SysCacheSupportingRelOidSize;
 
-static int	oid_compare(const void *a, const void *b);
-
 
 /*
  * InitCatalogCache - initialize the caches
@@ -1100,19 +1099,6 @@ InitCatalogCache(void)
 	Assert(SysCacheRelationOidSize <= lengthof(SysCacheRelationOid));
 	Assert(SysCacheSupportingRelOidSize <= lengthof(SysCacheSupportingRelOid));
 
-	/* Sort and de-dup OID arrays, so we can use binary search. */
-	pg_qsort(SysCacheRelationOid, SysCacheRelationOidSize,
-			 sizeof(Oid), oid_compare);
-	SysCacheRelationOidSize =
-		qunique(SysCacheRelationOid, SysCacheRelationOidSize, sizeof(Oid),
-				oid_compare);
-
-	pg_qsort(SysCacheSupportingRelOid, SysCacheSupportingRelOidSize,
-			 sizeof(Oid), oid_compare);
-	SysCacheSupportingRelOidSize =
-		qunique(SysCacheSupportingRelOid, SysCacheSupportingRelOidSize,
-				sizeof(Oid), oid_compare);
-
 	CacheInitialized = true;
 }
 
@@ -1552,22 +1538,7 @@ RelationInvalidatesSnapshotsOnly(Oid relid)
 bool
 RelationHasSysCache(Oid relid)
 {
-	int			low = 0,
-				high = SysCacheRelationOidSize - 1;
-
-	while (low <= high)
-	{
-		int			middle = low + (high - low) / 2;
-
-		if (SysCacheRelationOid[middle] == relid)
-			return true;
-		if (SysCacheRelationOid[middle] < relid)
-			low = middle + 1;
-		else
-			high = middle - 1;
-	}
-
-	return false;
+	return pg_lfind32(relid, SysCacheRelationOid, SysCacheRelationOidSize);
 }
 
 /*
@@ -1577,35 +1548,5 @@ RelationHasSysCache(Oid relid)
 bool
 RelationSupportsSysCache(Oid relid)
 {
-	int			low = 0,
-				high = SysCacheSupportingRelOidSize - 1;
-
-	while (low <= high)
-	{
-		int			middle = low + (high - low) / 2;
-
-		if (SysCacheSupportingRelOid[middle] == relid)
-			return true;
-		if (SysCacheSupportingRelOid[middle] < relid)
-			low = middle + 1;
-		else
-			high = middle - 1;
-	}
-
-	return false;
-}
-
-
-/*
- * OID comparator for pg_qsort
- */
-static int
-oid_compare(const void *a, const void *b)
-{
-	Oid			oa = *((const Oid *) a);
-	Oid			ob = *((const Oid *) b);
-
-	if (oa == ob)
-		return 0;
-	return (oa > ob) ? 1 : -1;
+	return pg_lfind32(relid, SysCacheSupportingRelOid, SysCacheSupportingRelOidSize);
 }
-- 
2.36.1