Re: [PERFORM] I/O on select count(*)

2008-05-17 Thread Greg Smith
I just collected all the good internals information included in this thread and popped it onto http://wiki.postgresql.org/wiki/Hint_Bits where I'll continue to hack away at the text until it's readable. Thanks to everyone who answered my questions here, that's good progress toward clearing up

Re: [PERFORM] I/O on select count(*)

2008-05-17 Thread Jeremy Harris
Tom Lane wrote: One additional point: this means that one transaction in every 32K writing transactions *does* have to do extra work when it assigns itself an XID, namely create and zero out the next page of pg_clog. And that doesn't just slow down the transaction in question, but the next few g