Re: Weird explain output - Mailing list pgsql-general

From wd
Subject Re: Weird explain output
Date
Msg-id CABexzmhRDSkGB+4sN+r7fsZHVQ+Otc77ybXy8CocHOJjW6HGnw@mail.gmail.com
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In response to Re: Weird explain output  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Thanks for your reply.


On Mon, Feb 4, 2013 at 3:48 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

> You're worrying about the wrong thing entirely.  The right thing to be
> worrying about is why are some of those row estimates off by four orders
> of magnitude, and what you can do to fix that.  The planner will never
> deliver sane plans when its estimates are so far off from reality.
>
>
You mean the rows from explain is bigger then the rows real returned?
It caused by a sub query with a filter like ( a and b ) or ( c and d ),
I've tried to create a temp table for it, the explained rows and the real
rows will similarly.

Here is the full output, http://explain.depesz.com/s/M7oo


> From my perspective, you snipped all the interesting parts of this
> output, because the misestimation is evidently happening somewhere down
> in there.
>
>                         regards, tom lane
>

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