--- \dll\postgresql-12.0\a\backend\access\brin\brin_validate.c	Mon Sep 30 17:06:55 2019
+++ brin_validate.c	Fri Nov 15 08:14:58 2019
@@ -57,8 +57,10 @@
 
 	/* Fetch opclass information */
 	classtup = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclassoid));
-	if (!HeapTupleIsValid(classtup))
+	if (!HeapTupleIsValid(classtup)) {
 		elog(ERROR, "cache lookup failed for operator class %u", opclassoid);
+        return false;
+    }
 	classform = (Form_pg_opclass) GETSTRUCT(classtup);
 
 	opfamilyoid = classform->opcfamily;
@@ -67,8 +69,11 @@
 
 	/* Fetch opfamily information */
 	familytup = SearchSysCache1(OPFAMILYOID, ObjectIdGetDatum(opfamilyoid));
-	if (!HeapTupleIsValid(familytup))
+	if (!HeapTupleIsValid(familytup)) {
 		elog(ERROR, "cache lookup failed for operator family %u", opfamilyoid);
+	    ReleaseSysCache(classtup);
+        return false;
+    }
 	familyform = (Form_pg_opfamily) GETSTRUCT(familytup);
 
 	opfamilyname = NameStr(familyform->opfname);