Re: query plan with index having a btrim is different for strings of different length

Richard Yen <dba@richyen.com> writes:
> Is there any way to tune this so that for the common last names, the query
> run time doesn't jump from <1s to >300s?

Well, as near as I can tell there's factor of a couple hundred
difference between the frequencies of 'smith' and 'smithers', so
you shouldn't really expect similar runtimes for the two cases.

Having said that, I still think you should try to index both first
and last name.  Also I wonder whether the index on owner is worth
having at all.  It definitely doesn't seem worthwhile to index the
entries with owner = -1, since there are so many; so maybe you could
make it a partial index that excludes those entries, in order to prevent
the planner from trying to use it for this case.

            regards, tom lane