In article <[EMAIL PROTECTED]>, "Merlin Moncure" <[EMAIL PROTECTED]> writes:
> On Mon, Apr 14, 2008 at 5:21 AM, Harald Fuchs <[EMAIL PROTECTED]> wrote: >> I think there's something sub-optimal with generate_series. >> In the following, "documents" is a table with more than 120000 rows, >> vacuumed and analyzed before the queries. > everything is working exactly as intended. while it's obvious to you > that the generate series function returns a particular number of rows > based on your supplied inputs, it's not (yet) obvious to the planner. Which was exactly my point. Since generate_series is a builtin function, the planner could theoretically know the number of rows returned, thus choosing a better plan. OTOH, the difference between theory and reality is in theory smaller than in reality. > your genser function supplies the hint the planner needs and it > adjusts the plan. most set returning functions (particularly > non-immutable ones) are not so easy to determine the # of rows from > the input parameters anyways. Yes, of course. I used "genser" just to show that there is a better plan. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
