[prev in list] [next in list] [prev in thread] [next in thread] 

List:       postgresql-general
Subject:    Re: [HACKERS] Group-count estimation statistics
From:       Tom Lane <tgl () sss ! pgh ! pa ! us>
Date:       2005-01-31 19:40:08
Message-ID: 22119.1107200408 () sss ! pgh ! pa ! us
[Download RAW message or body]

Manfred Koizar <mkoi-pg@aon.at> writes:
> That's not what I meant.  I tried to say that if we have a GROUP BY
> several columns and one of these columns alone has more than N/10
> distinct values, there's no way to get less than that many groups.

Oh, I see, you want a "max" calculation in there too.  Seems reasonable.
Any objections?

			regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
      joining column's datatypes do not match
[prev in list] [next in list] [prev in thread] [next in thread]