On 1/18/17 3:12 PM, Stephen Frost wrote: > I don't understand what I'm missing when it comes to checkpoint_timeout > and the time required to recover from a crash. You aren't the first > person to question that association, but it seems pretty clear to me. > > When doing recovery, we have to replay everything since the last > checkpoint. If we are checkpointing at least every 5 minutes then we > can't have any more than 5 minutes worth of WAL to replay, right?
But writing WAL and replaying WAL are two entirely different operations. Writing a WAL record involves writing a few bytes sequentially. Replaying a WAL record might involve hopping all over the system and applying the changes that the WAL record describes. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers