On Wed, Oct 1, 2008 at 10:27 AM, Tom Lane <[EMAIL PROTECTED]> wrote: >> 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.
I probably wouldn't compare checksumming *every* WAL record to a single block-level checksum. -- Jonah H. Harris, Senior DBA myYearbook.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
