On Mon, Jul 18, 2016 at 8:59 AM, Jan Wieck <j...@wi3ck.info> wrote: > > > On Mon, Jul 18, 2016 at 9:43 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> >> Merlin Moncure <mmonc...@gmail.com> writes: >> > BTW, while the fix does address the cleanup performance issue, it's >> > still the case that anonymous code blocks burn up lots of resident >> > memory (my 315k example I tested with ate around 8gb IIRC) when run >> > like this. My question is, if the pl/pgsql code block is anonymous >> > and not in some kind of a loop, why bother caching the plan at all? >> >> Nobody got around to it. Also, as you note, it's not as simple as >> "don't cache if in a DO block". You'd need to track whether you were >> inside any sort of looping construct. Depending on how difficult >> that turned out to be, it might add overhead to regular functions >> that we don't want. > > Agreed. And from the structures themselves it is not really easy to detect > if inside of a loop, the toplevel, while, for and if all use the same > statement > block and call exec_stmts(), which in turn calls exec_stmt() for each > element in that list. It is not impossible to add a flag, set at PL compile > time, to that element and check it every time, the statement is executed. > But such a change definitely needs more testing and probably won't > qualify for backpatching.
Right. Note, not arguing for backpatch here, just some open speculation and some evidence that we still have a problem (although nearly as nasty of one -- the pre-patch behavior of not responding to cancel is very dangerous and solved). Hm, maybe, instead of trying to figure out if in a loop, set a 'called' flag with each statement and only cache when touched the second time. (If that's easier, dunno). merlin -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
