Re: Re: Query not using index

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Chris Jones <chris@mt.sri.com>
Cc: ryan@paymentalliance.net, pgsql-general@postgresql.org
Date: 2001-05-10T21:43:15Z
Lists: pgsql-general
Chris Jones <chris@mt.sri.com> writes:
>> Ah.  You must have a few values that are far more frequent (like tens of
>> thousands of occurrences?) and these are throwing off the planner's
>> statistics.

> I had a similar situation, where I had a lot of rows with 0's in
> them.  Changing those to NULLs worked wonders.

Yes, if you have a lot of "dummy" values it's a good idea to represent
them as NULLs rather than some arbitrarily-chosen regular data value.
The planner does keep track of NULLs separately from everything else.

			regards, tom lane