From: Pavan Deolasee <pavan.deolasee@gmail.com>
Date: Thu, 5 May 2016 09:55:39 +0000 (+0530)
Subject: Make minimum values of shared_queues and shared_queue_size GUC parameters
X-Git-Tag: XL9_5_R1_1~11
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=df16e34abb020b92908b1f476079afbb190e547d;p=postgres-xl.git

Make minimum values of shared_queues and shared_queue_size GUC parameters
dependent on other settings

shared_queue_size is dependent on the number of datanodes in the cluster since
each datanode may attach itself as a consumer of the shared queue. So the
shared_queue_size now signifies per-datanode value and the actual value used
will be (max_datanodes * shared_queue_size). Existing users should modify their
settings after taking this into consideration.

Similarly, shared_queues highly depends on the number of concurrent queries. We
now conservatively set this to at least 1/4th of max_connections or user
specified value, whichever is higher.
---

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 0f419533ec..7108fb35ff 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2943,7 +2943,8 @@ static struct config_int ConfigureNamesInt[] =
 	 */
 	{
 		{"shared_queues", PGC_POSTMASTER, RESOURCES_MEM,
-			gettext_noop("Sets the number of shared memory queues used by the distributed executor."),
+			gettext_noop("Sets the number of shared memory queues used by the "
+					"distributed executor, minimum 1/4 of max_connections."),
 			NULL
 		},
 		&NSQueues,
@@ -2953,12 +2954,13 @@ static struct config_int ConfigureNamesInt[] =
 
 	{
 		{"shared_queue_size", PGC_POSTMASTER, RESOURCES_MEM,
-			gettext_noop("Sets the amount of memory allocated for a shared memory queue."),
+			gettext_noop("Sets the amount of memory allocated for a shared"
+					" memory queue per datanode."),
 			NULL,
 			GUC_UNIT_KB
 		},
 		&SQueueSize,
-		64, 1, MAX_KILOBYTES,
+		32, 1, MAX_KILOBYTES,
 		NULL, NULL, NULL
 	},
 
diff --git a/src/include/pgxc/squeue.h b/src/include/pgxc/squeue.h
index c0a9807e43..5d5e7136bd 100644
--- a/src/include/pgxc/squeue.h
+++ b/src/include/pgxc/squeue.h
@@ -25,9 +25,9 @@ extern PGDLLIMPORT int NSQueues;
 extern PGDLLIMPORT int SQueueSize;
 
 /* Fixed size of shared queue, maybe need to be GUC configurable */
-#define SQUEUE_SIZE ((long) SQueueSize * 1024L)
+#define SQUEUE_SIZE ((long) SQueueSize * MaxDataNodes * 1024L)
 /* Number of shared queues, maybe need to be GUC configurable */
-#define NUM_SQUEUES ((long) NSQueues)
+#define NUM_SQUEUES Max((long) NSQueues, MaxConnections / 4)
 
 #define SQUEUE_KEYSIZE (64)