Remove useless code from CreateReplicationSlot.

robertmhaas · robertmhaas · commit 902a2c280012 · 2021-10-25T10:57:12.000-04:00
According to the comments, we initialize sendTimeLineIsHistoric and sendTimeLine here for the benefit of WalSndSegmentOpen. However, the only way that can happen is if logical_read_xlog_page calls WALRead. And since logical_read_xlog_page initializes the same global variables internally, we don't need to also do it here. These initializations have been here since replication slots were introduced in commit 858ec11. They were certainly useless at that time, too, because logical decoding didn't yet exist then, and physical replication doesn't examine any WAL at the time of slot creation. I haven't checked all the intermediate versions, but I suspect there's no point at which this code ever did anything useful. To reduce future confusion, remove the code. Since there's no functional defect, no back-patch. Discussion: http://postgr.es/m/CA+TgmobSWzacEs+r6C-7DrOPDHoDar4i9gzxB3SCBr5qjnLmVQ@mail.gmail.com
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
@@ -1042,10 +1042,6 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
 
 	parseCreateReplSlotOptions(cmd, &reserve_wal, &snapshot_action, &two_phase);
 
-	/* setup state for WalSndSegmentOpen */
-	sendTimeLineIsHistoric = false;
-	sendTimeLine = ThisTimeLineID;
-
 	if (cmd->kind == REPLICATION_KIND_PHYSICAL)
 	{
 		ReplicationSlotCreate(cmd->slotname, false,

Original file line number	Diff line number	Diff line change
`@@ -1042,10 +1042,6 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)`
`1042`	`1042`
`1043`	`1043`	`parseCreateReplSlotOptions(cmd, &reserve_wal, &snapshot_action, &two_phase);`
`1044`	`1044`
`1045`		`- /* setup state for WalSndSegmentOpen */`
`1046`		`- sendTimeLineIsHistoric = false;`
`1047`		`- sendTimeLine = ThisTimeLineID;`
`1048`		`-`
`1049`	`1045`	`if (cmd->kind == REPLICATION_KIND_PHYSICAL)`
`1050`	`1046`	`{`
`1051`	`1047`	`ReplicationSlotCreate(cmd->slotname, false,`