| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Turning off HOT/Cleanup sometimes |
| Date: | 2014-09-17 19:42:08 |
| Message-ID: | CA+U5nMKc8b9TgsP1_7iTAy7TYMfYD0UPopOxXQxJh-RL=Mfbsg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 15 September 2014 22:13, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On 15 September 2014 17:09, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
>> Do we really want to disable HOT for all catalog scans?
>
> The intention of the patch is that catalog scans are treated
> identically to non-catalog scans. The idea here is that HOT cleanup
> only occurs on scans on target relations, so only INSERT, UPDATE and
> DELETE do HOT cleanup.
Since INSERT, UPDATE and DELETE can only be called when
!RecoveryInProgress(), we can completely avoid making this test at the
top of each heap_page_prune_opt() call.
I very much like the simplicity of saying "no target, no cleanup".
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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