| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | pgsql-hackers(at)postgresql(dot)org, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
| Subject: | Re: WIP: Faster Expression Processing v4 |
| Date: | 2017-03-15 22:16:57 |
| Message-ID: | 9137.1489616217@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andres Freund <andres(at)anarazel(dot)de> writes:
> On 2017-03-15 17:33:46 -0400, Tom Lane wrote:
>> We could make the planner mark each table scan node with the highest
>> column number that the plan will access, and use that to drive a
>> slot_getsomeattrs call in advance of any access to tuple contents.
> probably isn't sufficient - we build non-virtual tuples in a good number
> of places (sorts, tuplestore using stuff like nodeMaterial, nodeHash.c
> output, ...). I suspect it'd have measurable negative consequences if
> we removed the deforming logic for all expressions/projections above
> such nodes. I guess we could just do such a logic for every Plan node?
[ scratches head... ] What deforming logic do you think I'm proposing
removing?
regards, tom lane
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