Re: WAL insert delay settings - Mailing list pgsql-hackers

From Peter Geoghegan
Subject Re: WAL insert delay settings
Date
Msg-id CAH2-Wzkzop9kyO5F82-O=HnBn3qJCaGSLMDoGhvTHGJKub-cvg@mail.gmail.com
Whole thread Raw
In response to WAL insert delay settings  (Peter Eisentraut <peter.eisentraut@2ndquadrant.com>)
Responses Re: WAL insert delay settings  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
On Wed, Feb 13, 2019 at 4:16 AM Peter Eisentraut
<peter.eisentraut@2ndquadrant.com> wrote:
> Bulk operations like CREATE INDEX, ALTER TABLE, or bulk loads can create
> a lot of WAL.  A lot of WAL at once can cause delays in replication.
> For synchronous replication, this can make seemingly unrelated sessions
> hang.  But also for asynchronous replication, it will increase latency.

I think that I suggested a feature like this early during my time at
Heroku, about 5 years ago. There would occasionally be cases where ops
would find it useful to throttle WAL writing using their own terrible
kludge (it involved sending SIGSTOP to the WAL writer).

I recall that this idea was not well received at the time. I still
think it's a good idea, though. Provided there is a safe way to get it
to work.

-- 
Peter Geoghegan


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