On Fri, Jun 12, 2015 at 4:52 PM, David G. Johnston < david.g.johns...@gmail.com> wrote:
> On Fri, Jun 12, 2015 at 4:37 PM, Michael Nolan <htf...@gmail.com> wrote: > >> The only thing I can come up that's happened since last night was that we >> ran the nightly vacuum analyze on that database, but I did not change the >> statistics target. >> > > > The answer to your question is no, parameters changes are worse would > take effect after a reboot - though most are used on the very next query > that runs. > > The vacuum would indeed likely account for the gains - there being > significantly fewer dead/invisible rows to have to scan over and discard > while retrieving the live rows that fulfill your query. > > David J. > > I wouldn't have said there was much activity in those tables since the previous day's vacuum, maybe a couple hundred rows changed or added in a table that has nearly 900,000 rows, and the other tables involved probably even less than that. There may be one table with more activity, perhaps 20,000 row updates and maybe a few dozen new rows in a table that has 400,000 rows. Maybe I need to manually analyze that table more often? Vacuum analyze verbose generate way too much output, is there a way to get some more straight forward numbers from an analyze? I'm definitely not complaining about the improvement, I'm just trying to get a handle on what really caused it and whether I can improve it even further. -- Mike Nolan
