Re: Turning off HOT/Cleanup sometimes

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От Stephen Frost
Тема Re: Turning off HOT/Cleanup sometimes
Дата
Msg-id 20140109182811.GO2686@tamriel.snowman.net
обсуждение исходный текст
Ответ на Re: Turning off HOT/Cleanup sometimes  (Alvaro Herrera <alvherre@2ndquadrant.com>)
Ответы Re: Turning off HOT/Cleanup sometimes  (Tom Lane <tgl@sss.pgh.pa.us>)
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* Alvaro Herrera (alvherre@2ndquadrant.com) wrote:
> But in a
> SELECT, the effect is only that you will have to skip less dead tuples,
> which is not as exciting.

Agreed.  There's also the option to have it be done based on some
expectation of future work- that is, if we have to traverse X number of
dead tuples during a select, then don't bother with HOT pruning, but if
we get up to X+Y dead tuples, then do HOT pruning.

That said, I'm not entirely convinced that traversing these dead tuples
is all *that* painful during SELECT.  If there's that many levels then
hopefully it's not long til an UPDATE comes along and cleans them up.
Thanks,
    Stephen

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