Merge pull request #2859 from citusdata/no_null_percent_s

Avoid segfault in logging queries

src/backend/distributed/executor/multi_executor.c

@@ -442,7 +442,7 @@ ExecuteQueryIntoDestReceiver(Query *query, ParamListInfo params, DestReceiver *d
 
 
 /*
- * ExecuteIntoDestReceiver plans and executes a query and sends results to the given
+ * ExecutePlanIntoDestReceiver executes a query plan and sends results to the given
  * DestReceiver.
  */
 void

src/backend/distributed/planner/deparse_shard_query.c

@@ -111,6 +111,7 @@ RebuildQueryStrings(Query *originalQuery, List *taskList)
 		}
 
 		ereport(DEBUG4, (errmsg("query before rebuilding: %s",
+								task->queryString == NULL ? "(null)" :
 								ApplyLogRedaction(task->queryString))));
 
 		UpdateTaskQueryString(query, relationId, valuesRTE, task);

src/backend/distributed/shared_library_init.c

@@ -175,9 +175,8 @@ _PG_init(void)
 	 * (thus as the innermost/last running hook) to be able to do our
 	 * duties. For simplicity insist that all hooks are previously unused.
 	 */
-	if (planner_hook != NULL || ProcessUtility_hook != NULL || ExecutorStart_hook !=
-		NULL ||
-		ExecutorRun_hook != NULL)
+	if (planner_hook != NULL || ProcessUtility_hook != NULL ||
+		ExecutorStart_hook != NULL || ExecutorRun_hook != NULL)
 	{
 		ereport(ERROR, (errmsg("Citus has to be loaded first"),
 						errhint("Place citus at the beginning of "