Fix clobbering of proc entry's statusFlags during slot invalidation ReplicationSlotRelease() copied MyProc->statusFlags unconditionally when resetting PROC_IN_LOGICAL_DECODING, using its pgxactoff to decide which area to update.
Slot invalidations can be done by the checkpointer or the startup process, and ReplicationSlotRelease() ignored the fact that pgxactoff is only meaningful for processes in the proc array, that auxiliary processes never join. pgxactoff would remain at 0 for these, meaning that an incorrect set of status flags would be updated. The consequences of this issue could be various, depending on the statsFlags lost in the proc slot incorrectly overwritten. Losing PROC_AFFECTS_ALL_HORIZONS has been mentioned as the worse case, causing VACUUM to remove rows a standby may needs even if standby feedback is enabled. Assertions failures are another possibility. Let's skip the update of statusFlags unless PROC_IN_LOGICAL_DECODING is set. Nothing but StartupDecodingContext() sets it, and no auxiliary processes call it. Author: Vlad Lesin <[email protected]> Reviewed-by: Hayato Kuroda <[email protected]> Reviewed-by: Michael Paquier <[email protected]> Discussion: https://postgr.es/m/[email protected] Backpatch-through: 14 Branch ------ REL_18_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/c5666f7e16ca6845dac21b46bb2704038b35dad7 Modified Files -------------- src/backend/replication/slot.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)
