Nishad Prakash <prakashn@uci.edu> writes:
> An index on a certain table is not being used if a column referenced in
> the query has more than a certain number of rows for a given value.
This is not a bug; it's intended and correct behavior.
You may have an issue that the crossover point isn't very well tuned for
your environment. If so, the answer is to fool with the optimizer cost
parameters. See the plgsql-performance archives...
regards, tom lane