"Merlin Moncure" <mmoncure(at)gmail(dot)com> writes:
> prepared statements have the same problem. IIRC the planner assumes
> 10%, which will often drop to a seqscan or a bitmap index scan. Some
> years back I argued (unsuccessfully) to have the planner guess 100
> rows or something like that. Ideally, I think it would generate the
> plan from the value passed into the first invocation of the function.
I believe it's the case that that will happen now in the same contexts
where the planner uses the first value of any other parameter (ie,
unnamed statements in the extended-query protocol).
regards, tom lane