Excerpts from Tom Lanyon's message of mié abr 18 12:44:11 -0300 2012:
> Hi all,
>
> To satisfy my own curiosity, I was trying to find where 8.4 kicks into a backwards scan of the data file during
(auto-)vacuuming.
>
> This appears to be repair_frag() in backend/commands/vacuum.c, but only appears to be called by a FULL vacuum.
Autovacuum,however, appears to explicitly only ever call a not-FULL vacuum, so I'm trying to see where and how it would
bepossible for autovacuum to trigger this operation. Any pointers?
See lazy_truncate_heap in vacuumlazy.c.
--
Álvaro Herrera <alvherre@commandprompt.com>
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