On February 10, 2005 10:58 am, Tom Lane wrote: > Chris Kratz <[EMAIL PROTECTED]> writes: > > Does anyone have any idea why there be over a 4s difference between > > running the statement directly and using explain analyze? > > > > Aggregate (cost=9848.12..9848.12 rows=1 width=0) (actual > > time=4841.231..4841.235 rows=1 loops=1) > > -> Seq Scan on answer (cost=0.00..8561.29 rows=514729 width=0) > > (actual time=0.011..2347.762 rows=530576 loops=1) > > Total runtime: 4841.412 ms > > EXPLAIN ANALYZE's principal overhead is two gettimeofday() kernel calls > per plan node execution, so 1061154 such calls here. I infer that > gettimeofday takes about 4 microseconds on your hardware ... which seems > a bit slow for modern machines. What sort of box is it?
dvl reported the same thing on #postgresql some months back, and neilc was/is/did looking into it. I belive he came up with a way to move the function call outside of the loop with no ill effects to the rest of the expected behavior. > > regards, tom lane > > ---------------------------(end of broadcast)--------------------------- > TIP 4: Don't 'kill -9' the postmaster -- Darcy Buskermolen Wavefire Technologies Corp. ph: 250.717.0200 fx: 250.763.1759 http://www.wavefire.com ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
