Обсуждение: Standby reads fail when autovacuum take AEL during truncation
Hello hackers, I was faced on $SUBJECT on an heavily updated table and the same table heavily accessed on standby server. I notice autovacuum try to take an AEL in lazy_truncate_heap(). On primary we try during VACUUM_TRUNCATE_LOCK_WAIT_INTERVAL (50ms) and we failed after several attempts. But we do not have this mechanism on a standby, AEL could lock simple SELECT during the RelationTruncate(). Please note, this can occurs even with hot_standby_feedback = on I wonder how we can improve this? Maybe by introducing an option to disable truncation for autovacuum on specific table? Thanks!
Hi! On Fri, Sep 7, 2018 at 3:17 PM Adrien NAYRAT <adrien.nayrat@anayrat.info> wrote: > I was faced on $SUBJECT on an heavily updated table and the same table > heavily accessed on standby server. > > I notice autovacuum try to take an AEL in lazy_truncate_heap(). On > primary we try during VACUUM_TRUNCATE_LOCK_WAIT_INTERVAL (50ms) and we > failed after several attempts. > > But we do not have this mechanism on a standby, AEL could lock simple > SELECT during the RelationTruncate(). > > Please note, this can occurs even with hot_standby_feedback = on > > I wonder how we can improve this? Maybe by introducing an option to > disable truncation for autovacuum on specific table? Please, take a look at following threads: 1. https://www.postgresql.org/message-id/c9374921e50a5e8fb1ecf04eb8c6ebc3%40postgrespro.ru 2. https://www.postgresql.org/message-id/CAHGQGwE5UqFqSq1%3DkV3QtTUtXphTdyHA-8rAj4A%3DY%2Be4kyp3BQ%40mail.gmail.com ------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
On 9/7/18 7:36 PM, Alexander Korotkov wrote: > Please, take a look at following threads: > 1.https://www.postgresql.org/message-id/c9374921e50a5e8fb1ecf04eb8c6ebc3%40postgrespro.ru > 2.https://www.postgresql.org/message-id/CAHGQGwE5UqFqSq1%3DkV3QtTUtXphTdyHA-8rAj4A%3DY%2Be4kyp3BQ%40mail.gmail.com Thanks, I will to these threads.