Performance commit. The get_extension_oid routine is too heavy.

danolivo · danolivo · commit 15b664f03583 · 2021-10-04T15:27:09.000+05:00
Pointlessly to call it on each planning hook execution.
diff --git a/aqo.c b/aqo.c
@@ -31,6 +31,8 @@ void _PG_init(void);
 
 /* Strategy of determining feature space for new queries. */
 int		aqo_mode;
+bool	aqo_enabled = false; /* Signals that CREATE EXTENSION have executed and
+								all extension tables is ready for use. */
 bool	force_collect_stat;
 
 /*
diff --git a/aqo.h b/aqo.h
@@ -168,6 +168,7 @@ typedef enum
 }	AQO_MODE;
 
 extern int	aqo_mode;
+extern bool	aqo_enabled;
 extern bool	force_collect_stat;
 extern bool aqo_show_hash;
 extern bool aqo_show_details;
diff --git a/preprocessing.c b/preprocessing.c
@@ -93,6 +93,30 @@ call_default_planner(Query *parse,
 								boundParams);
 }
 
+/*
+ * Check, that a 'CREATE EXTENSION aqo' command has been executed.
+ * This function allows us to execute the get_extension_oid routine only once
+ * at each backend.
+ * If any AQO-related table is missed we will set aqo_enabled to false (see
+ * a storage implementation module).
+ */
+static bool
+aqoIsEnabled(void)
+{
+	if (creating_extension)
+		/* Nothing to tell in this mode. */
+		return false;
+
+	if (aqo_enabled)
+		/* Fast path. Dropping should be detected by absence of any table. */
+		return true;
+
+	if (get_extension_oid("aqo", true) != InvalidOid)
+		aqo_enabled = true;
+
+	return aqo_enabled;
+}
+
 /*
  * Before query optimization we determine machine learning settings
  * for the query.
@@ -120,18 +144,23 @@ aqo_planner(Query *parse,
 	  * the heap during planning. Transactions is synchronized between parallel
 	  * sections. See GetCurrentCommandId() comments also.
 	  */
-	if ((parse->commandType != CMD_SELECT && parse->commandType != CMD_INSERT &&
+	if (!aqoIsEnabled() ||
+		(parse->commandType != CMD_SELECT && parse->commandType != CMD_INSERT &&
 		parse->commandType != CMD_UPDATE && parse->commandType != CMD_DELETE) ||
-		strstr(application_name, "postgres_fdw") != NULL || /* Prevent distributed deadlocks */
-		strstr(application_name, "pgfdw:") != NULL || /* caused by fdw */
-		get_extension_oid("aqo", true) == InvalidOid ||
 		creating_extension ||
 		IsInParallelMode() || IsParallelWorker() ||
 		(aqo_mode == AQO_MODE_DISABLED && !force_collect_stat) ||
+		strstr(application_name, "postgres_fdw") != NULL || /* Prevent distributed deadlocks */
+		strstr(application_name, "pgfdw:") != NULL || /* caused by fdw */
 		isQueryUsingSystemRelation(parse) ||
 		RecoveryInProgress())
 	{
+		/*
+		 * We should disable AQO for this query to remember this decision along
+		 * all execution stages.
+		 */
 		disable_aqo_for_query();
+
 		return call_default_planner(parse,
 									query_string,
 									cursorOptions,
diff --git a/storage.c b/storage.c
@@ -60,7 +60,16 @@ open_aqo_relation(char *heaprelnspname, char *heaprelname,
 	*hrel = table_openrv_extended(rv,  lockmode, true);
 	if (!OidIsValid(reloid) || *hrel == NULL)
 	{
+		/*
+		 * Absence of any AQO-related table tell us that someone executed
+		 * a 'DROP EXTENSION aqo' command. We disable AQO for all future queries
+		 * in this backend. For performance reasons we do it locally.
+		 * Also, we gently disable AQO for the rest of the current query
+		 * execution process.
+		 */
+		aqo_enabled = false;
 		disable_aqo_for_query();
+
 		return false;
 	}
 
