On 22 October 2013 10:15 Amit Kapila wrote: >>On Mon, Oct 21, 2013 at 10:54 AM, Haribabu kommi <haribabu.ko...@huawei.com> >>wrote: >> >> Yes, it's correct. "nkeep" counter have the dead tuples which are recently >> dead and are not vacuumed. The removal of tuples vacuumed from dead tuples >> should be the same as "nkeep" counter. >> So if we remove the nkeep from num_tuples which gives us the proper live >> tuples. How about following statement at the end scan for all blocks. >> >> num_tuples -= nkeep; > >Actually what I had in mind was to use nkeep to estimate n_dead_tuples similar >to how num_tuples is used to estimate n_live_tuples. I think it will match >what Tom had pointed in his response (>>>>What >>would make more sense to me is for VACUUM to estimate the number >>>>>of remaining dead tuples somehow and send that in its message. >>>>>However, since the whole point here is that we aren't accounting for >>>>>transactions that commit while VACUUM runs, it's not very clear how >>>>>to do that.)
I changed the patch as passing the "nkeep" counter data as the new dead tuples in the relation to stats like the new_rel_tuples. The "nkeep" counter is an approximation of dead tuples data of a relation. Instead of resetting dead tuples stats as zero, used this value to set n_dead_tuples same as n_live_tuples. Patch is attached in the mail. Please let me know if any changes are required. Regards, Hari Babu.
vacuum_fix_v3.patch
Description: vacuum_fix_v3.patch
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