On 06/21/17 04:51, Heikki Linnakangas wrote: > (I'm cleaning up my inbox, hence the delayed reply)
I had almost completely forgotten ever bringing it up. :) > When I wrote that code, I don't remember if I realized that we're > initializing the page headers, or if I thought that it's good enough even if > we do. I guess I didn't realize it, because a comment would've been in order > if it was intentional. > > So +1 on fixing that, a patch would be welcome. Ok, that sounds like something I could take a whack at. Overall, xlog.c is a bit daunting, but this particular detail seems fairly approachable. > In the meanwhile, have you > tried using a different compression program? Something else than gzip might > do a better job at the almost zero pages. Well, gzip was doing pretty well; it could get a 16 MB segment file down to under 27 kB, or less than 14 bytes for each of 2000 pages, when a page header is what, 20 bytes, it looks like? I'm not sure how much better I'd expect a (non-custom) compression scheme to do. The real difference comes between compressing (even well) a large unchanged area, versus being able to recognize (again with a non-custom tool) that the whole area is unchanged. -Chap -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
