Re: Really dumb planner decision

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От Robert Haas
Тема Re: Really dumb planner decision
Дата
Msg-id 603c8f070904160442l361465b7i6c3a168956eb5c24@mail.gmail.com
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Ответ на Re: Really dumb planner decision  (Matthew Wakeling <matthew@flymine.org>)
Ответы Re: Really dumb planner decision
Список pgsql-performance
2009/4/16 Matthew Wakeling <matthew@flymine.org>:
> On Thu, 16 Apr 2009, Grzegorz Jaśkiewicz wrote:
>>
>> On Thu, Apr 16, 2009 at 11:37 AM, Matthew Wakeling <matthew@flymine.org>
>> wrote:
>>>
>>> I have a query that is executed really badly by Postgres. It is a nine
>>> table
>>> join, where two of the tables are represented in a view. If I remove one
>>> of
>>> the tables from the query, then the query runs very quickly using a
>>> completely different plan.
>>
>> And what happens if you execute that view alone, with WHERE .. just
>> like it would be a part of the whole query? ((id = 1267676))
>
> Really quick, just like the query that works in my email.

What happens if you change join_collapse_limit and from_collapse_limit
to some huge number?

http://www.postgresql.org/docs/current/static/runtime-config-query.html#GUC-FROM-COLLAPSE-LIMIT

...Robert

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