"Pavan Deolasee" <[EMAIL PROTECTED]> writes: > Please see the attached patch. One change I made is to hold the SHARE lock > on the page while ANALYZE is reading tuples from it. I thought it would > be a right thing to do instead of repeatedly acquiring/releasing the lock.
Bruce pointed out to me off-list that this patch is closely related to the patch I proposed awhile back for ANALYZE *overcounting* dead tuples. That one is on the current commit-fest list because we held it over after this discussion: http://archives.postgresql.org/pgsql-hackers/2007-11/msg00771.php On reflection it seems to me that we allowed ourselves to get distracted by schemes for reducing the error attributable to the uncertain state of in-doubt tuples. That's still something interesting to think about, but we forgot the fact that there's a serious problem in 8.3 and the patches we have would clearly make it better. What I propose therefore is combining this patch with my older one so that ANALYZE counts according to the following rules: REDIRECT line pointer: ignore DEAD line pointer: count as dead HEAPTUPLE_LIVE tuple: count as live, include in statistics pool HEAPTUPLE_DEAD: count as dead HEAPTUPLE_RECENTLY_DEAD: count as dead HEAPTUPLE_INSERT_IN_PROGRESS: ignore HEAPTUPLE_DELETE_IN_PROGRESS: count as live We might want to adjust these rules later after more thought, but in any case ANALYZE has to be fixed to be able to distinguish these cases in the first place. This is better than what we have and is reasonable to back-patch. Trying to reduce the race conditions for in-doubt tuples should go on the TODO list. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
