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