Hello hackers, Currently, promotion related handling is missing in the slot sync SQL function pg_sync_replication_slots(). Here is the background on how it is done in slot sync worker: During promotion, the startup process in order to shut down the slot-sync worker, sets the 'stopSignaled' flag, sends the shut-down signal, and waits for slot sync worker to exit. Meanwhile if the postmaster has not noticed the promotion yet, it may end up restarting slot sync worker. In such a case, the worker exits if 'stopSignaled' is set.
Since there is a chance that the user (or any of his scripts/tools) may execute SQL function pg_sync_replication_slots() in parallel to promotion, such handling is needed in this SQL function as well, The attached patch attempts to implement the same. Changes are: 1) If pg_sync_replication_slots() is already running when the promotion is triggered, ShutDownSlotSync() checks the 'SlotSyncCtx->syncing' flag as well and waits for it to become false i.e. waits till parallel running SQL function is finished. 2) If pg_sync_replication_slots() is invoked when promotion is already in progress, pg_sync_replication_slots() respects the 'stopSignaled' flag set by the startup process and becomes a no-op. thanks Shveta
v1-0001-Handle-stopSignaled-during-sync-function-call.patch
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