| From: | Gregory Stark <stark(at)enterprisedb(dot)com> |
|---|---|
| To: | tgl(at)postgresql(dot)org (Tom Lane) |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: pgsql: Tweak order of operations in BitmapHeapNext() to avoid the case |
| Date: | 2009-01-12 17:19:05 |
| Message-ID: | 87ab9wl9x2.fsf@oxford.xeocode.com |
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| Lists: | pgsql-committers pgsql-hackers |
tgl(at)postgresql(dot)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's PostgreSQL training!
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