On Tue, Oct 13, 2009 at 10:14 AM, Kevin Grittner <kevin.gritt...@wicourts.gov> wrote: > Robert Haas <robertmh...@gmail.com> wrote: > >> I sometimes want to know what the planner thinks the cost of some >> plan other than the one actually selected would be. > > Another DBMS I used for years had a way to turn on an *extremely* > verbose mode for their planner; it showed everything it considered > with its related cost information. Even a moderately complex query > generated hundreds or thousands of lines of output, so I rarely used > it; but for those particularly stubborn queries, where you just can't > understand why it's picking the plan it is, a little work wading > through the output would *always* clear up the mystery. > > Now that we can generate EXPLAIN output in more structured formats, > perhaps we could think about adding an "extremely verbose" mode where > the planner would "think out loud" as a whole separate section from > where we show the chosen plan?
I wouldn't object to such a thing, but for simple cases I think it would be more convenient to modify the planner's assumptions and then try replanning. An exhaustive dump of everything the planner has considered is going to be a LOT of data, and I don't really want to have to set up a graphical visualization tool every time I have a planning question. I am a command-line kind of guy... ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
