Pallav Kalva <pkalva@livedatagroup.com> writes:
> why does it have different plans for different values
Because the values occur different numbers of times (or so it thinks
anyway). If the rowcount estimates are far from reality, perhaps
increasing the statistics target would help. However, since you
only showed EXPLAIN and not EXPLAIN ANALYZE output, no one can
really tell whether the optimizer did anything wrong here.
regards, tom lane