Re: Performance query about large tables, lots of concurrent access

"Karl Wright" <kwright@metacarta.com> writes:

>> In this case it looks like the planner is afraid that that's exactly
>> what will happen --- a cost of 14177 suggests that several thousand row
>> fetches are expected to happen, and yet it's only predicting 5 rows out
>> after the filter.  It's using this plan anyway because it has no better
>> alternative, but you should think about whether a different index
>> definition would help.

Another index won't help if the reason the cost is so high isn't because the
index isn't very selective but because there are lots of dead tuples.

--
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com