Avoid accumulating relation locks during sequence synchronization. While collecting the sequences to synchronize, the sequence sync worker opened each INIT sequence with RowExclusiveLock and held it until the transaction committed. With many such sequences, this could exhaust the shared lock table and fail with "out of shared memory".
The worker only reads each sequence's identity (namespace and name) here and needs it to stay stable while read, for which AccessShareLock is enough, as it conflicts with the AccessExclusiveLock taken by DROP, RENAME, and SET SCHEMA. Take that lock instead and release it as soon as the identity is read. The later synchronization re-opens each sequence, so it does not rely on the lock being retained. Reported-by: Noah Misch <[email protected]> Author: vignesh C <[email protected]> Reviewed-by: Hayato Kuroda <[email protected]> Reviewed-by: Amit Kapila <[email protected]> Backpatch-through: 19, where it was introduced Discussion: https://postgr.es/m/[email protected] Branch ------ REL_19_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/e46c2a65710f021e25bc0fcf404dd00c86aec1d7 Modified Files -------------- src/backend/replication/logical/sequencesync.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)
