Re: Make EXPLAIN generate a generic plan for a parameterized query
От | Julien Rouhaud |
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Тема | Re: Make EXPLAIN generate a generic plan for a parameterized query |
Дата | |
Msg-id | 20221011160348.dptd53h4bfg7cv5v@jrouhaud обсуждение исходный текст |
Ответ на | Re: Make EXPLAIN generate a generic plan for a parameterized query (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: Make EXPLAIN generate a generic plan for a parameterized query
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Список | pgsql-hackers |
On Tue, Oct 11, 2022 at 09:49:14AM -0400, Tom Lane wrote: > > If you're trying to investigate custom-plan behavior, then you > need to supply concrete parameter values somewhere, so I think > this approach is fine for that case. (Shoehorning parameter > values into EXPLAIN options seems like it'd be a bit much.) > However, investigating generic-plan behavior this way is tedious, > since you have to invent irrelevant parameter values, plus mess > with plan_cache_mode or else run the explain half a dozen times. > So I can get behind having a more convenient way for that. One common use case is tools identifying a slow query using pg_stat_statements, identifying some missing indexes and then wanting to check whether the index should be useful using some hypothetical index. FTR I'm working on such a project and for now we have to go to great lengths trying to "unjumble" such queries, so having a way to easily get the answer for a generic plan would be great.
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