Don't warn about creating temporary or unlogged hash indexes.

Warning people that no WAL-logging will be done doesn't make sense
in this case.

Michael Paquier

src/backend/commands/indexcmds.c

@@ -490,7 +490,8 @@ DefineIndex(Oid relationId,
 	accessMethodId = HeapTupleGetOid(tuple);
 	accessMethodForm = (Form_pg_am) GETSTRUCT(tuple);
 
-	if (strcmp(accessMethodName, "hash") == 0)
+	if (strcmp(accessMethodName, "hash") == 0 &&
+		RelationNeedsWAL(rel))
 		ereport(WARNING,
 				(errmsg("hash indexes are not WAL-logged and their use is discouraged")));
 

src/test/regress/expected/create_index.out

@@ -2342,6 +2342,9 @@ CREATE INDEX hash_txt_index ON hash_txt_heap USING hash (random text_ops);
 WARNING:  hash indexes are not WAL-logged and their use is discouraged
 CREATE INDEX hash_f8_index ON hash_f8_heap USING hash (random float8_ops);
 WARNING:  hash indexes are not WAL-logged and their use is discouraged
+CREATE UNLOGGED TABLE unlogged_hash_table (id int4);
+CREATE INDEX unlogged_hash_index ON unlogged_hash_table USING hash (id int4_ops);
+DROP TABLE unlogged_hash_table;
 -- CREATE INDEX hash_ovfl_index ON hash_ovfl_heap USING hash (x int4_ops);
 --
 -- Test functional index

src/test/regress/sql/create_index.sql

@@ -684,6 +684,10 @@ CREATE INDEX hash_txt_index ON hash_txt_heap USING hash (random text_ops);
 
 CREATE INDEX hash_f8_index ON hash_f8_heap USING hash (random float8_ops);
 
+CREATE UNLOGGED TABLE unlogged_hash_table (id int4);
+CREATE INDEX unlogged_hash_index ON unlogged_hash_table USING hash (id int4_ops);
+DROP TABLE unlogged_hash_table;
+
 -- CREATE INDEX hash_ovfl_index ON hash_ovfl_heap USING hash (x int4_ops);