On Tue, Aug 15, 2006 at 05:38:43PM -0400, mark@xxxxxxxxxxxxxx wrote: > I didn't know that the xlog segment only uses pre-allocated space. I > ignore mtime/atime as they don't count as file system structure > changes to me. It's updating a field in place. No change to the structure. > > With the pre-allocation knowledge, I agree with you. Not sure how I > missed that in my reviewing of the archives... I did know it > pre-allocated once upon a time... Hmm.... This is only valid if the pre-allocation is also fsync'd *and* fsync ensures that both the metadata and file data are on disk. Anyone actually checked that? :) BTW, I did see some anecdotal evidence on one of the lists a while ago. A PostgreSQL DBA had suggested doing a 'pull the power cord' test to the other DBAs (all of which were responsible for different RDBMSes, including a bunch of well known names). They all thought he was off his rocker. Not too long after that, an unplanned power outage did occur, and PostgreSQL was the only RDBMS that recovered every single database without intervention. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@xxxxxxxxxxxxx Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
