diff --git a/src/backend/utils/cache/inval.c b/src/backend/utils/cache/inval.c
index 62c4369b171..7e4bef3c6ba 100644
--- a/src/backend/utils/cache/inval.c
+++ b/src/backend/utils/cache/inval.c
@@ -461,10 +461,13 @@ RegisterRelcacheInvalidation(Oid dbId, Oid relId)
 	(void) GetCurrentCommandId(true);
 
 	/*
-	 * If the relation being invalidated is one of those cached in the
+	 * If the relation being invalidated is one of those cached in the local
 	 * relcache init file, mark that we need to zap that file at commit.
+	 * (Note: perhaps it would be better if this code were a bit more
+	 * decoupled from the knowledge that the init file contains exactly those
+	 * non-shared rels used in catalog caches.)
 	 */
-	if (RelationIdIsInInitFile(relId))
+	if (OidIsValid(dbId) && RelationSupportsSysCache(relId))
 		transInvalInfo->RelcacheInitFileInval = true;
 }
 
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 296c0631ee1..f5e43d486f4 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -130,14 +130,6 @@ bool		criticalSharedRelcachesBuilt = false;
  */
 static long relcacheInvalsReceived = 0L;
 
-/*
- * This list remembers the OIDs of the non-shared relations cached in the
- * database's local relcache init file.  Note that there is no corresponding
- * list for the shared relcache init file, for reasons explained in the
- * comments for RelationCacheInitFileRemove.
- */
-static List *initFileRelationIds = NIL;
-
 /*
  * eoxact_list[] stores the OIDs of relations that (might) need AtEOXact
  * cleanup work.  This list intentionally has limited size; if it overflows,
@@ -3190,9 +3182,6 @@ RelationCacheInitializePhase3(void)
 		 */
 		InitCatalogCachePhase2();
 
-		/* reset initFileRelationIds list; we'll fill it during write */
-		initFileRelationIds = NIL;
-
 		/* now write the files */
 		write_relcache_init_file(true);
 		write_relcache_init_file(false);
@@ -4477,10 +4466,6 @@ load_relcache_init_file(bool shared)
 	for (relno = 0; relno < num_rels; relno++)
 	{
 		RelationCacheInsert(rels[relno]);
-		/* also make a list of their OIDs, for RelationIdIsInInitFile */
-		if (!shared)
-			initFileRelationIds = lcons_oid(RelationGetRelid(rels[relno]),
-											initFileRelationIds);
 	}
 
 	pfree(rels);
@@ -4517,9 +4502,15 @@ write_relcache_init_file(bool shared)
 	int			magic;
 	HASH_SEQ_STATUS status;
 	RelIdCacheEnt *idhentry;
-	MemoryContext oldcxt;
 	int			i;
 
+	/*
+	 * If we have already received any relcache inval events, there's no
+	 * chance of succeeding so we may as well skip the whole thing.
+	 */
+	if (relcacheInvalsReceived != 0L)
+		return;
+
 	/*
 	 * We must write a temporary file and rename it into place. Otherwise,
 	 * another backend starting at about the same time might crash trying to
@@ -4579,6 +4570,16 @@ write_relcache_init_file(bool shared)
 		if (relform->relisshared != shared)
 			continue;
 
+		/*
+		 * Ignore if not supposed to be in init file.  We can allow any shared
+		 * relation that's been loaded so far to be in the shared init file,
+		 * but unshared relations must be used for catalog caches.  (Note: if
+		 * you want to change the criterion for rels to be kept in the init
+		 * file, see also inval.c.)
+		 */
+		if (!shared && !RelationSupportsSysCache(RelationGetRelid(rel)))
+			continue;
+
 		/* first write the relcache entry proper */
 		write_item(rel, sizeof(RelationData), fp);
 
@@ -4635,15 +4636,6 @@ write_relcache_init_file(bool shared)
 					   relform->relnatts * sizeof(int16),
 					   fp);
 		}
-
-		/* also make a list of their OIDs, for RelationIdIsInInitFile */
-		if (!shared)
-		{
-			oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
-			initFileRelationIds = lcons_oid(RelationGetRelid(rel),
-											initFileRelationIds);
-			MemoryContextSwitchTo(oldcxt);
-		}
 	}
 
 	if (FreeFile(fp))
@@ -4702,21 +4694,6 @@ write_item(const void *data, Size len, FILE *fp)
 		elog(FATAL, "could not write init file");
 }
 
-/*
- * Detect whether a given relation (identified by OID) is one of the ones
- * we store in the local relcache init file.
- *
- * Note that we effectively assume that all backends running in a database
- * would choose to store the same set of relations in the init file;
- * otherwise there are cases where we'd fail to detect the need for an init
- * file invalidation.  This does not seem likely to be a problem in practice.
- */
-bool
-RelationIdIsInInitFile(Oid relationId)
-{
-	return list_member_oid(initFileRelationIds, relationId);
-}
-
 /*
  * Invalidate (remove) the init file during commit of a transaction that
  * changed one or more of the relation cache entries that are kept in the
diff --git a/src/backend/utils/cache/syscache.c b/src/backend/utils/cache/syscache.c
index 9aa5ee5ac05..94fc568d6e7 100644
--- a/src/backend/utils/cache/syscache.c
+++ b/src/backend/utils/cache/syscache.c
@@ -791,11 +791,18 @@ static const struct cachedesc cacheinfo[] = {
 	}
 };
 
-static CatCache *SysCache[
-						  lengthof(cacheinfo)];
-static int	SysCacheSize = lengthof(cacheinfo);
+#define SysCacheSize	((int) lengthof(cacheinfo))
+
+static CatCache *SysCache[SysCacheSize];
+
 static bool CacheInitialized = false;
 
+/* Sorted 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
@@ -809,10 +816,12 @@ void
 InitCatalogCache(void)
 {
 	int			cacheId;
+	int			i,
+				j;
 
 	Assert(!CacheInitialized);
 
-	MemSet(SysCache, 0, sizeof(SysCache));
+	SysCacheSupportingRelOidSize = 0;
 
 	for (cacheId = 0; cacheId < SysCacheSize; cacheId++)
 	{
@@ -825,7 +834,25 @@ InitCatalogCache(void)
 		if (!PointerIsValid(SysCache[cacheId]))
 			elog(ERROR, "could not initialize cache %u (%d)",
 				 cacheinfo[cacheId].reloid, cacheId);
+		/* Accumulate data for OID lists, too */
+		SysCacheSupportingRelOid[SysCacheSupportingRelOidSize++] =
+			cacheinfo[cacheId].reloid;
+		SysCacheSupportingRelOid[SysCacheSupportingRelOidSize++] =
+			cacheinfo[cacheId].indoid;
 	}
+
+	Assert(SysCacheSupportingRelOidSize <= lengthof(SysCacheSupportingRelOid));
+
+	/* Sort and de-dup OID arrays, so we can use binary search. */
+	pg_qsort(SysCacheSupportingRelOid, SysCacheSupportingRelOidSize,
+			 sizeof(Oid), oid_compare);
+	for (i = 1, j = 0; i < SysCacheSupportingRelOidSize; i++)
+	{
+		if (SysCacheSupportingRelOid[i] != SysCacheSupportingRelOid[j])
+			SysCacheSupportingRelOid[++j] = SysCacheSupportingRelOid[i];
+	}
+	SysCacheSupportingRelOidSize = j + 1;
+
 	CacheInitialized = true;
 }
 
@@ -1113,3 +1140,43 @@ SearchSysCacheList(int cacheId, int nkeys,
 	return SearchCatCacheList(SysCache[cacheId], nkeys,
 							  key1, key2, key3, key4);
 }
+
+/*
+ * Test whether a relation supports a system cache, ie it is either a
+ * cached table or the index used for a cache.
+ */
+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;
+}
diff --git a/src/include/utils/relcache.h b/src/include/utils/relcache.h
index 39b98f2568e..49c84b8cea8 100644
--- a/src/include/utils/relcache.h
+++ b/src/include/utils/relcache.h
@@ -105,7 +105,6 @@ extern void AtEOSubXact_RelationCache(bool isCommit, SubTransactionId mySubid,
 /*
  * Routines to help manage rebuilding of relcache init files
  */
-extern bool RelationIdIsInInitFile(Oid relationId);
 extern void RelationCacheInitFilePreInvalidate(void);
 extern void RelationCacheInitFilePostInvalidate(void);
 extern void RelationCacheInitFileRemove(void);
diff --git a/src/include/utils/syscache.h b/src/include/utils/syscache.h
index d1d8abe0a90..8dc00102bfe 100644
--- a/src/include/utils/syscache.h
+++ b/src/include/utils/syscache.h
@@ -18,7 +18,7 @@
 
 #include "access/attnum.h"
 #include "access/htup.h"
-/* we purposedly do not include utils/catcache.h here */
+/* we intentionally do not include utils/catcache.h here */
 
 /*
  *		SysCache identifiers.
@@ -125,6 +125,8 @@ struct catclist;
 extern struct catclist *SearchSysCacheList(int cacheId, int nkeys,
 				   Datum key1, Datum key2, Datum key3, Datum key4);
 
+extern bool RelationSupportsSysCache(Oid relid);
+
 /*
  * The use of the macros below rather than direct calls to the corresponding
  * functions is encouraged, as it insulates the caller from changes in the