Re: pgsql: Tweak order of operations in BitmapHeapNext() to avoid the case

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От Gregory Stark
Тема Re: pgsql: Tweak order of operations in BitmapHeapNext() to avoid the case
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Msg-id 87ab9wl9x2.fsf@oxford.xeocode.com
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Ответы Re: pgsql: Tweak order of operations in BitmapHeapNext() to avoid the case  (Tom Lane <tgl@sss.pgh.pa.us>)
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tgl@postgresql.org (Tom Lane) writes:

> Log Message:
> -----------
> Tweak order of operations in BitmapHeapNext() to avoid the case of prefetching
> the same page we are nanoseconds away from reading for real.  There should be
> something left to do on the current page before we consider issuing a prefetch.

Doesn't this break things if, say, there's precisely one tuple on every page?
You'll keep raising the prefetch_target but never actually prefetch anything.

--  Gregory Stark EnterpriseDB          http://www.enterprisedb.com Get trained by Bruce Momjian - ask me about
EnterpriseDB'sPostgreSQL training!
 


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