Re: [PERFORM] Query much slower when run from postgres function
| От | Mario Splivalo |
|---|---|
| Тема | Re: [PERFORM] Query much slower when run from postgres function |
| Дата | |
| Msg-id | 49B56D4D.9090605@megafon.hr обсуждение исходный текст |
| Ответ на | Re: [PERFORM] Query much slower when run from postgres function (Guillaume Cottenceau <gc@mnc.ch>) |
| Список | pgsql-jdbc |
Guillaume Cottenceau wrote:
>>> Now I'm confused, why is 'sql' function much slower than 'direct' SELECT?
>> Usually the reason for this is that the planner chooses a different plan
>> when it has knowledge of the particular value you are searching for than
>> when it does not.
>
> Yes, and since Mario is coming from JDBC, I'll share my part on
> this: I also noticed some very wrong plans in JDBC because of the
> "optimization" in prepared statements consisting of planning once
> for all runs, e.g. without any parameter values to help planning.
>
For what is worth:
When I call postgres function via JDBC, I have almost the same execution
time as when calling function from psql.
When I call SELECT COUNT(*)... WHERE... query from JDBC, I again have
almost the same execution time as when executing query from psql.
Postgres function takes around 200ms, and SELECT query takes around 2-4ms.
Mike
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