On Tue, 2007-03-27 at 11:52 +0900, Koichi Suzuki wrote: > Here's an update of a code to improve full page writes as proposed in > > http://archives.postgresql.org/pgsql-hackers/2007-01/msg01491.php > and > http://archives.postgresql.org/pgsql-patches/2007-01/msg00607.php > > Update includes some modification for error handling in archiver and > restoration command. > > In the previous threads, I posted several evaluation and shown that we > can keep all the full page writes needed for full XLOG crash recovery, > while compressing archive log size considerably better than gzip, with > less CPU consumption. I've found no further objection for this proposal > but still would like to hear comments/opinions/advices.
Koichi-san, Looks interesting. I like the small amount of code to do this. A few thoughts: - Not sure why we need "full_page_compress", why not just mark them always? That harms noone. (Did someone else ask for that? If so, keep it) - OTOH I'd like to see an explicit parameter set during recovery since you're asking the main recovery path to act differently in case a single bit is set/unset. If you are using that form of recovery, we should say so explicitly, to keep everybody else safe. - I'd rather mark just the nonremovable blocks. But no real difference - We definitely don't want an normal elog in a XLogInsert critical section, especially at DEBUG1 level - diff -c format is easier and the standard - pg_logarchive and pg_logrestore should be called by a name that reflects what they actually do. Possibly pg_compresslog and pg_decompresslog etc.. I've not reviewed those programs, but: - Not sure why we have to compress away page headers. Touch as little as you can has always been my thinking with recovery code. - I'm very uncomfortable with touching the LSN. Maybe I misunderstand? - Have you thought about how pg_standby would integrate with this option? Can you please? - I'll do some docs for this after Freeze, if you'd like. I have some other changes to make there, so I can do this at the same time. -- Simon Riggs EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend