Re: Turning off HOT/Cleanup sometimes

On Sun, Sep 14, 2014 at 4:37 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On 12 September 2014 18:19, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> On 12 September 2014 15:30, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
>>> After a little bit I remembered there was already a function for this.
>>> So specifically, I'd suggest using ExecRelationIsTargetRelation()
>>> to decide whether to mark the scan as requiring pruning.
>>
>> Sounds cool. Thanks both, this is sounding like a viable route now.
>
> Yes, this is viable.
>
> Patch attached, using Alvaro's idea of use-case specific pruning and
> Tom's idea of aiming at target relations. Patch uses or extends
> existing infrastructure, so its shorter than it might have been, yet
> with all that bufmgr yuck removed.
>
> This is very, very good because while going through this I notice the
> dozen or more places where we were pruning blocks in annoying places I
> didn't even know about such as about 4-5 constraint checks. In more
> than a few DDL commands like ALTER TABLE and CLUSTER we were even
> pruning the old relation prior to rewrite.

Do we really want to disable HOT for all catalog scans?

--
Robert Haas
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