Il giorno sab, 15/07/2006 alle 13.04 -0700, Joe Conway ha scritto: > Gabriele Turchi wrote: > > Running an ANALYZE really change the plan, now it is fast as before > > (8.0). > > > > On the production system a VACUUM FULL ANALYZE is run every morning > > after a clean-up, when the "registrazioni" table is empty. During the > > day this table fills up (about 500 record any day), and apparently the > > performances are free-falling very quickly. This behaviour has not > > changed between the old and the new installation. > > > > Can you suggest an easy way to collect and keep up-to-date these > > statistics in a very low-impact way? > > > > Why not just periodically (once an hour?) run "ANALYZE registrazioni;" > during the day. This will only update the statistics, and should be very > low impact. > This is my "solution" too... but: is enough? Or else: there is a better way to do this? If the performance in the better case is 50 times faster than the worse case, during an hour (50/100 record inserted in "registrazioni") how much the performance can fall before the new "ANALYZE" is run? Otherwise, running ANALYZE more frequently can badly affect the overall performance? A so big difference in postgres performance, can be considered a bug or a over-optimization in the plan making? Why (at least apparently) the 8.0 version is not affected? > HTH, > > Joe > > ---------------------------(end of broadcast)--------------------------- > TIP 6: explain analyze is your friend Thank you all very much, Gabriele
