doc: Add note about promotion waits on backends stuck sending to clients. Commit df1be4ddc83 made promotion skip waiting for the barrier that refreshes each process's cached logical WAL logging state in some cases, but promotion still waits for it on a standby with wal_level = replica that has a valid logical slot. A backend blocked sending data to a client that has stopped reading can't process the barrier, so promotion can wait for a long time.
Add a note about this case in the failover section, along with ways to get out of the wait and to bound it in advance. Backpatch to v19, where commit 67c20979ce7 introduced this wait. Author: shihao zhong <[email protected]> Reviewed-by: Amit Kapila <[email protected]> Reviewed-by: Hayato Kuroda <[email protected]> Reviewed-by: shveta malik <[email protected]> Reviewed-by: Zhijie Hou <[email protected]> Reviewed-by: Masahiko Sawada <[email protected]> Discussion: https://postgr.es/m/cagrkxqtobk9c2spagha-kcgxjhvwn90j1scyuxrvydq51lk...@mail.gmail.com Backpatch-through: 19 Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/b936425002c54abab86dab151efdbb6952314388 Modified Files -------------- doc/src/sgml/high-availability.sgml | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+)
