List wait events in alphabetical order

This changes the documentation, and the related structures so as
everything is consistent.

Some wait events were not listed alphabetically since their
introduction, others have been added rather randomly.  Keeping all those
entries in order helps in maintenance, and helps the user looking at the
documentation.

Author: Michael Paquier, Kuntal Ghosh
Discussion: https://postgr.es/m/20181024002539.GI1658@paquier.xyz
Backpatch-through: 10, only for the documentation part to avoid an ABI
breakage.

doc/src/sgml/monitoring.sgml

@@ -1193,14 +1193,14 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
          <entry><literal>CheckpointerMain</literal></entry>
          <entry>Waiting in main loop of checkpointer process.</entry>
         </row>
-        <row>
-         <entry><literal>LogicalLauncherMain</literal></entry>
-         <entry>Waiting in main loop of logical launcher process.</entry>
-        </row>
         <row>
          <entry><literal>LogicalApplyMain</literal></entry>
          <entry>Waiting in main loop of logical apply process.</entry>
         </row>
+        <row>
+         <entry><literal>LogicalLauncherMain</literal></entry>
+         <entry>Waiting in main loop of logical launcher process.</entry>
+        </row>
         <row>
          <entry><literal>PgStatMain</literal></entry>
          <entry>Waiting in main loop of the statistics collector process.</entry>
@@ -1280,6 +1280,10 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
          <entry><literal>BtreePage</literal></entry>
          <entry>Waiting for the page number needed to continue a parallel B-tree scan to become available.</entry>
         </row>
+        <row>
+         <entry><literal>ClogGroupUpdate</literal></entry>
+         <entry>Waiting for group leader to update transaction status at transaction end.</entry>
+        </row>
         <row>
          <entry><literal>ExecuteGather</literal></entry>
          <entry>Waiting for activity from child process when executing <literal>Gather</literal> node.</entry>
@@ -1368,10 +1372,6 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
          <entry><literal>MessageQueueSend</literal></entry>
          <entry>Waiting to send bytes to a shared message queue.</entry>
         </row>
-        <row>
-         <entry><literal>ParallelFinish</literal></entry>
-         <entry>Waiting for parallel workers to finish computing.</entry>
-        </row>
         <row>
          <entry><literal>ParallelBitmapScan</literal></entry>
          <entry>Waiting for parallel bitmap scan to become initialized.</entry>
@@ -1381,12 +1381,12 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
          <entry>Waiting for parallel <command>CREATE INDEX</command> workers to finish heap scan.</entry>
         </row>
         <row>
-         <entry><literal>ProcArrayGroupUpdate</literal></entry>
-         <entry>Waiting for group leader to clear transaction id at transaction end.</entry>
+         <entry><literal>ParallelFinish</literal></entry>
+         <entry>Waiting for parallel workers to finish computing.</entry>
         </row>
         <row>
-         <entry><literal>ClogGroupUpdate</literal></entry>
-         <entry>Waiting for group leader to update transaction status at transaction end.</entry>
+         <entry><literal>ProcArrayGroupUpdate</literal></entry>
+         <entry>Waiting for group leader to clear transaction id at transaction end.</entry>
         </row>
         <row>
          <entry><literal>ReplicationOriginDrop</literal></entry>

src/backend/postmaster/pgstat.c

@@ -3484,12 +3484,12 @@ pgstat_get_wait_activity(WaitEventActivity w)
 		case WAIT_EVENT_CHECKPOINTER_MAIN:
 			event_name = "CheckpointerMain";
 			break;
-		case WAIT_EVENT_LOGICAL_LAUNCHER_MAIN:
-			event_name = "LogicalLauncherMain";
-			break;
 		case WAIT_EVENT_LOGICAL_APPLY_MAIN:
 			event_name = "LogicalApplyMain";
 			break;
+		case WAIT_EVENT_LOGICAL_LAUNCHER_MAIN:
+			event_name = "LogicalLauncherMain";
+			break;
 		case WAIT_EVENT_PGSTAT_MAIN:
 			event_name = "PgStatMain";
 			break;
@@ -3582,6 +3582,9 @@ pgstat_get_wait_ipc(WaitEventIPC w)
 		case WAIT_EVENT_BTREE_PAGE:
 			event_name = "BtreePage";
 			break;
+		case WAIT_EVENT_CLOG_GROUP_UPDATE:
+			event_name = "ClogGroupUpdate";
+			break;
 		case WAIT_EVENT_EXECUTE_GATHER:
 			event_name = "ExecuteGather";
 			break;
@@ -3648,21 +3651,18 @@ pgstat_get_wait_ipc(WaitEventIPC w)
 		case WAIT_EVENT_MQ_SEND:
 			event_name = "MessageQueueSend";
 			break;
-		case WAIT_EVENT_PARALLEL_FINISH:
-			event_name = "ParallelFinish";
-			break;
 		case WAIT_EVENT_PARALLEL_BITMAP_SCAN:
 			event_name = "ParallelBitmapScan";
 			break;
 		case WAIT_EVENT_PARALLEL_CREATE_INDEX_SCAN:
 			event_name = "ParallelCreateIndexScan";
 			break;
+		case WAIT_EVENT_PARALLEL_FINISH:
+			event_name = "ParallelFinish";
+			break;
 		case WAIT_EVENT_PROCARRAY_GROUP_UPDATE:
 			event_name = "ProcArrayGroupUpdate";
 			break;
-		case WAIT_EVENT_CLOG_GROUP_UPDATE:
-			event_name = "ClogGroupUpdate";
-			break;
 		case WAIT_EVENT_REPLICATION_ORIGIN_DROP:
 			event_name = "ReplicationOriginDrop";
 			break;

src/include/pgstat.h

@@ -759,8 +759,8 @@ typedef enum
 	WAIT_EVENT_BGWRITER_HIBERNATE,
 	WAIT_EVENT_BGWRITER_MAIN,
 	WAIT_EVENT_CHECKPOINTER_MAIN,
-	WAIT_EVENT_LOGICAL_LAUNCHER_MAIN,
 	WAIT_EVENT_LOGICAL_APPLY_MAIN,
+	WAIT_EVENT_LOGICAL_LAUNCHER_MAIN,
 	WAIT_EVENT_PGSTAT_MAIN,
 	WAIT_EVENT_RECOVERY_WAL_ALL,
 	WAIT_EVENT_RECOVERY_WAL_STREAM,
@@ -802,6 +802,7 @@ typedef enum
 	WAIT_EVENT_BGWORKER_SHUTDOWN = PG_WAIT_IPC,
 	WAIT_EVENT_BGWORKER_STARTUP,
 	WAIT_EVENT_BTREE_PAGE,
+	WAIT_EVENT_CLOG_GROUP_UPDATE,
 	WAIT_EVENT_EXECUTE_GATHER,
 	WAIT_EVENT_HASH_BATCH_ALLOCATING,
 	WAIT_EVENT_HASH_BATCH_ELECTING,
@@ -810,25 +811,24 @@ typedef enum
 	WAIT_EVENT_HASH_BUILD_ELECTING,
 	WAIT_EVENT_HASH_BUILD_HASHING_INNER,
 	WAIT_EVENT_HASH_BUILD_HASHING_OUTER,
+	WAIT_EVENT_HASH_GROW_BATCHES_ALLOCATING,
+	WAIT_EVENT_HASH_GROW_BATCHES_DECIDING,
 	WAIT_EVENT_HASH_GROW_BATCHES_ELECTING,
 	WAIT_EVENT_HASH_GROW_BATCHES_FINISHING,
 	WAIT_EVENT_HASH_GROW_BATCHES_REPARTITIONING,
-	WAIT_EVENT_HASH_GROW_BATCHES_ALLOCATING,
-	WAIT_EVENT_HASH_GROW_BATCHES_DECIDING,
+	WAIT_EVENT_HASH_GROW_BUCKETS_ALLOCATING,
 	WAIT_EVENT_HASH_GROW_BUCKETS_ELECTING,
 	WAIT_EVENT_HASH_GROW_BUCKETS_REINSERTING,
-	WAIT_EVENT_HASH_GROW_BUCKETS_ALLOCATING,
 	WAIT_EVENT_LOGICAL_SYNC_DATA,
 	WAIT_EVENT_LOGICAL_SYNC_STATE_CHANGE,
 	WAIT_EVENT_MQ_INTERNAL,
 	WAIT_EVENT_MQ_PUT_MESSAGE,
 	WAIT_EVENT_MQ_RECEIVE,
 	WAIT_EVENT_MQ_SEND,
-	WAIT_EVENT_PARALLEL_FINISH,
 	WAIT_EVENT_PARALLEL_BITMAP_SCAN,
 	WAIT_EVENT_PARALLEL_CREATE_INDEX_SCAN,
+	WAIT_EVENT_PARALLEL_FINISH,
 	WAIT_EVENT_PROCARRAY_GROUP_UPDATE,
-	WAIT_EVENT_CLOG_GROUP_UPDATE,
 	WAIT_EVENT_REPLICATION_ORIGIN_DROP,
 	WAIT_EVENT_REPLICATION_SLOT_DROP,
 	WAIT_EVENT_SAFE_SNAPSHOT,