On 12 September 2014 18:19, Simon Riggs <simon@2ndquadrant.com> wrote:
> On 12 September 2014 15:30, Tom Lane <tgl@sss.pgh.pa.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.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
