Re: Redesigning checkpoint_segments

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