On Wednesday 01 October 2008 10:27:52 Tom Lane wrote: > [EMAIL PROTECTED] writes: > >> No, it's all about time penalties and loss of concurrency. > > > > I don't think that the amount of time it would take to calculate and test > > the sum is even important. It may be in older CPUs, but these days CPUs > > are so fast in RAM and a block is very small. On x86 systems, depending > > on page alignment, we are talking about two or three pages that will be > > "in memory" (They were used to read the block from disk or previously > > accessed). > > Your optimism is showing ;-). XLogInsert routinely shows up as a major > CPU hog in any update-intensive test, and AFAICT that's mostly from the > CRC calculation for WAL records. >
Yeah... for those who run on filesystems that do checksumming for you, I'd bet they'd much rather see time spent in turning that off rather than checksumming everything else. (just guessing) -- Robert Treat Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers