Re: join over 12 tables takes 3 secs to plan

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От Hilmar Lapp
Тема Re: join over 12 tables takes 3 secs to plan
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Msg-id B3DCB6D1-1E95-11D7-9244-000393B4BFF6@gmx.net
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Ответ на Re: join over 12 tables takes 3 secs to plan  (Tom Lane <tgl@sss.pgh.pa.us>)
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Re: join over 12 tables takes 3 secs to plan
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Thanks for the pointer Tom. The application that's generating those
queries is open source, so I could even go in and hack the query
generating code accordingly, but I doubt I can spare that time. Given
the information in the document you pointed me at and Neil's email I
assume there is no other immediate remedy.

As an added note, appreciating that query optimization is a difficult
problem, and I do think PostgreSQL is a great product. Having said
that, I've written 16-table joins for Oracle and always found them to
plan within a second or two, so that's why I thought there's nothing
special about the query I posted ... I'm not saying this to be bashful
about PostgreSQL, but rather to suggest that apparently there are ways
to do it pretty fast.

I'm only starting to use PostgreSQL and making experiences, so I'm
asking for forgiveness what may occasionally seem to be ignorant ...

    -hilmar

On Thursday, January 2, 2003, at 12:24  PM, Tom Lane wrote:

> Hilmar Lapp <hlapp@gmx.net> writes:
>> I have a query generated by an application (not mine, but there's
>> nothing I can find that looks bad about the query itself) that takes
>> an
>> excessive amount of time to return even though there are almost no
>> rows
>> in the schema yet.
>
> Read
> http://www.ca.postgresql.org/users-lounge/docs/7.3/postgres/explicit-
> joins.html
>
>             regards, tom lane
>
>
--
-------------------------------------------------------------
Hilmar Lapp                            email: lapp at gnf.org
GNF, San Diego, Ca. 92121              phone: +1-858-812-1757
-------------------------------------------------------------


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