From: Tatsuo Ishii <ishii@sraoss.co.jp>
Date: Mon, 16 Sep 2019 00:24:08 +0000 (+0900)
Subject: Fix occasional query hang while processing DEALLOCATE.
X-Git-Tag: V3_4_26~13
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=14a7b822530878069ab14dca99e0fb26fc6597ee;p=pgpool2.git

Fix occasional query hang while processing DEALLOCATE.

When DEALLOCATE tries to remove a named statement, it inherits
where_to_send map of the named statement in
where_to_send_deallocate(). However it forgot to copy the load balance
node id in the query context of the named statement. This made sending
query to backend not happen: if the target node id is different from
query_context->load_balance_node_id nor primary node id,
pool_virtual_master_db_node_id (it is called as MASTER_NODE_ID)
returns primary node id, and pool_send_and_wait(MASTER_NODE_ID)
ignores the request because VALID_BACKEND returns false in this case
(MASTER_NODE_ID = primary node id is not in the where_to_send map). As
a result, following check_error() waits for response from backend in
vain.

Fix is, let where_to_send_deallocate() copy load balance node id from
the query context of the previous named statement.

Per bug 546.
---

diff --git a/src/context/pool_query_context.c b/src/context/pool_query_context.c
index 1b0c1db78..b82e43870 100644
--- a/src/context/pool_query_context.c
+++ b/src/context/pool_query_context.c
@@ -1272,10 +1272,13 @@ void where_to_send_deallocate(POOL_QUERY_CONTEXT *query_context, Node *node)
 			/* Inherit same map from PREPARE or PARSE */
 			pool_copy_prep_where(msg->query_context->where_to_send,
 								 query_context->where_to_send);
-			return;
+
+			/* copy load balance node id as well */
+			query_context->load_balance_node_id = msg->query_context->load_balance_node_id;
 		}
-		/* prepared statement was not found */
-		pool_setall_node_to_be_sent(query_context);
+		else
+			/* prepared statement was not found */
+			pool_setall_node_to_be_sent(query_context);
 	}
 }