Cédric Villemain <cedric.villemain.debian@gmail.com> writes:
> 2011/5/29 Tom Lane <tgl@sss.pgh.pa.us>:
>> OK, do you like the attached version of that logic? �(Other fragments
>> of the patch as before.)
> The idea was that remove only one page from the VACUUM will prevent
> relfrozenxid update and reltuples (and relpages) update.
> Now, I beleive that once we've skip at least one page thanks to
> SKIP_PAGES_THRESHOLD, then we should be more agressive and remove as
> many as possible pages from the VACUUM, tks to the VM.
That would require proof, not just suggestion. Skipping pages will
defeat the OS read-ahead algorithm, and so could easily cost more than
reading them.
regards, tom lane
