On Thu, Feb 03, 2011 at 02:11:58AM -0800, david@xxxxxxx wrote: > On Thu, 3 Feb 2011, Vitalii Tymchyshyn wrote: > >> 02.02.11 20:32, Robert Haas ???????(??): >>> Yeah. Any kind of bulk load into an empty table can be a problem, >>> even if it's not temporary. When you load a bunch of data and then >>> immediately plan a query against it, autoanalyze hasn't had a chance >>> to do its thing yet, so sometimes you get a lousy plan. >> >> May be introducing something like 'AutoAnalyze' threshold will help? I >> mean that any insert/update/delete statement that changes more then x% of >> table (and no less then y records) must do analyze right after it was >> finished. >> Defaults like x=50 y=10000 should be quite good as for me. > > If I am understanding things correctly, a full Analyze is going over all > the data in the table to figure out patterns. > > If this is the case, wouldn't it make sense in the situation where you are > loading an entire table from scratch to run the Analyze as you are > processing the data? If you don't want to slow down the main thread that's > inserting the data, you could copy the data to a second thread and do the > analysis while it's still in RAM rather than having to read it off of disk > afterwords. > > this doesn't make sense for updates to existing databases, but the use case > of loading a bunch of data and then querying it right away isn't _that_ > uncommon. > > David Lang > +1 for in-flight ANALYZE. This would be great for bulk loads of real tables as well as temp tables. Cheers, Ken -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
