Re: [PATCH] Reuse Workers and Replication Slots during Logical Replication

I see that setting originname in the catalog before actually creating it causes issues. My concern with setting originname when setting the state to FINISHEDCOPY is that if worker waits until FINISHEDCOPY to update slot/origin name but it fails somewhere before reaching FINISHEDCOPY and after creating slot/origin, then this new created slot/origin will be left behind. It wouldn't be possible to find and drop them since their names are not stored in the catalog. Eventually, this might also cause hitting the max_replication_slots limit in case of such failures between origin creation and FINISHEDCOPY.

One fix I can think is to update the catalog right after creating a new origin. But this would also require commiting the current transaction to actually persist the originname. I guess this action of commiting the transaction in the middle of initial sync could hurt the copy process.

ReplicationSlotDropAtPubNode(LogRepWorkerWalRcvConn, prev_slotname, true);

StartTransactionCommand();
/* Replication origin might still exist. Try to drop */
replorigin_drop_by_name(originname, true, false);

/*
* Remove replication slot and origin name from the relation's
* catalog record
*/
UpdateSubscriptionRel(MyLogicalRepWorker->subid,
 MyLogicalRepWorker->relid,
 MyLogicalRepWorker->relstate,
 MyLogicalRepWorker->relstate_lsn,
 NULL,
 NULL);