| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Dmitry Dolgov <9erthalion6(at)gmail(dot)com> |
| 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 17:11:40 |
| Message-ID: | 10432.1528045900@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Dmitry Dolgov <9erthalion6(at)gmail(dot)com> writes:
> 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?
I think the entire approach is wrong here. Rather than concerning
yourself with Params, or any other specific expression type, you
should be using !contain_volatile_functions() to decide whether
an expression is run-time-constant. If it is, use the regular
expression evaluation machinery to extract the value.
regards, tom lane
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