| From: | Josh Berkus <josh(at)agliodbs(dot)com> |
|---|---|
| To: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> |
| Cc: | Peter Eisentraut <peter_e(at)gmx(dot)net>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Redesigning checkpoint_segments |
| Date: | 2015-01-02 22:28:35 |
| Message-ID: | 54A71B93.3000905@agliodbs.com |
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| Lists: | pgsql-hackers |
On 01/02/2015 01:57 AM, Heikki Linnakangas wrote:
> wal_keep_segments does not affect the calculation of CheckPointSegments.
> If you set wal_keep_segments high enough, checkpoint_wal_size will be
> exceeded. The other alternative would be to force a checkpoint earlier,
> i.e. lower CheckPointSegments, so that checkpoint_wal_size would be
> honored. However, if you set wal_keep_segments high enough, higher than
> checkpoint_wal_size, it's impossible to honor checkpoint_wal_size no
> matter how frequently you checkpoint.
So you're saying that wal_keep_segments is part of the max_wal_size
total, NOT in addition to it?
Just asking for clarification, here. I think that's a fine idea, I just
want to make sure I understood you. The importance of wal_keep_segments
will be fading as more people use replication slots.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
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