On 2014-12-30 21:23:38 +0900, Michael Paquier wrote: > On Tue, Dec 30, 2014 at 6:21 PM, Jeff Davis <pg...@j-davis.com> wrote: > > On Fri, 2013-08-30 at 09:57 +0300, Heikki Linnakangas wrote: > >> Speeding up the CRC calculation obviously won't help with the WAL volume > >> per se, ie. you still generate the same amount of WAL that needs to be > >> shipped in replication. But then again, if all you want to do is to > >> reduce the volume, you could just compress the whole WAL stream. > > > > Was this point addressed? > Compressing the whole record is interesting for multi-insert records, > but as we need to keep the compressed data in a pre-allocated buffer > until WAL is written, we can only compress things within a given size > range. The point is, even if we define a lower bound, compression is > going to perform badly with an application that generates for example > many small records that are just higher than the lower bound... > Unsurprisingly for small records this was bad:
So why are you bringing it up? That's not an argument for anything, except not doing it in such a simplistic way. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
