On Mon, Sep 22, 2008 at 11:25 PM, Alex Hunsaker <[EMAIL PROTECTED]> wrote: > On Sun, Sep 14, 2008 at 8:16 PM, Tom Lane <[EMAIL PROTECTED]> wrote: >> BTW, one thing I noticed was that the hash index build time for the >> "wide column" case got a lot worse after applying the patch (from 56 to >> 237 sec). The reason for this turned out to be that with the smaller >> predicted index size, the code decided not to use the pre-sorting method >> that was recently added. Reducing effective_cache_size to less than the >> index size brought the time back down, to about 54 sec. So it would >> seem that effective_cache_size is too large a cutoff value. I'm >> considering changing hashbuild to switch over at shared_buffers instead >> of effective_cache_size --- any thoughts about that? > > Switching to shared_buffers gets my vote, on my test table with > 50,000,000 rows it takes about 8 minutes to create an index using the > default effective_cache_size. With effective_cache_size set to 6GB > (machine has 8GB) its still going an hour later.
Agreed. I think using shared_buffers as a cutoff is a much better idea as well. -- Jonah H. Harris, Senior DBA myYearbook.com -- Sent via pgsql-patches mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-patches