| From: | Dmitry Dolgov <9erthalion6(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: why partition pruning doesn't work? |
| Date: | 2018-06-03 16:44:33 |
| Message-ID: | CA+q6zcVL=7as7ud5ZNgndH_ytUn-h1=q_v8Cqpfea4-LULweMw@mail.gmail.com |
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| Lists: | pgsql-hackers |
> On 1 June 2018 at 17:53, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com> writes:
>> I think the patch is right if we were to handle only SQLValueFunction,
>> but the bigger picture here is that we aren't evaluating stable
>> functions before run-time partition pruning happens.
>
> I agree though that it seems strange to special-case SQLValueFunction
> rather than any-stable-expression. As long as the evaluation happens
> at executor start (i.e. with the query's run-time snapshot) it should
> be reasonable to simplify any stable expression.
Just to clarify for myself, for evaluating any stable function here would it be
enough to handle all function-like expressions (FuncExpr / OpExpr /
DistinctExpr / NullIfExpr) and check a corresponding function for provolatile,
like in the attached patch?
| Attachment | Content-Type | Size |
|---|---|---|
| partpruning_stable_func.patch | application/octet-stream | 2.9 KB |
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