| From: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Why we don't want hints |
| Date: | 2011-02-14 07:01:37 |
| Message-ID: | AANLkTik8hhy9UOAMgQnM-=fi0eZ0x=0=o=b=_N=qJxHY@mail.gmail.com |
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| Thread: | |
| Lists: | pgsql-hackers pgsql-performance |
On Sun, Feb 13, 2011 at 10:49 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>
>> I fail to see how 1 through 3 can tell the planner the correlation
>> between two fields in two separate tables.
>
> CREATE CORRELATION_ESTIMATE ( table1.colA ) = ( table2.colB ) IS 0.3
>
> ... and then it fixes the correlation for *every* query in the database, not
> just that one. And is easy to fix if the correlation changes.
I like that. Even better, could we setup some kind of simple command
to tell analyze to collect stats for the two columns together?
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