On Sat, Jan 30, 2010 at 12:26 PM, Jaime Casanova <jcasa...@systemguards.com.ec> wrote: > On Thu, Jan 28, 2010 at 4:18 PM, Robert Haas <robertmh...@gmail.com> wrote: >> On Sun, Jan 24, 2010 at 12:30 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >>> Robert Haas <robertmh...@gmail.com> writes: >>>> On Sun, Jan 24, 2010 at 12:06 AM, Jaime Casanova >>>>> why not let it go in ANALYZE, just as the sort info >>> >>>> It's kinda long-winded - it adds like 4 extra lines for each hash >>>> join. I don't think I want to add that much clutter to regular E-A >>>> output. >>> >>> Well, that would only happen if you're deliberately obtuse about the >>> formatting. The sort code manages to fit all the extra on one line, >>> and I don't see why hash couldn't. >> >> OK, here's a new version. >> > > OK, i have 3 hashes in a query and i got these 3 lines in an EXPLAIN > ANALYZE with your patch > """ > -> Hash (cost=3878.94..3878.94 rows=83594 > width=34) (actual time=504.648..504.648 rows=83594 loops=1) > Buckets: 2048 Batches: 8 Memory Usage: 589kB > [...] > -> Hash (cost=14.49..14.49 rows=649 width=15) > (actual time=2.901..2.901 rows=649 loops=1) > Buckets: 1024 Batches: 1 Memory Usage: 32kB > [...] > -> Hash (cost=977.62..977.62 rows=6555 width=16) > (actual time=60.913..60.913 rows=6556 loops=1) > Buckets: 1024 Batches: 1 Memory Usage: 308kB > """ > > I guess Memory Usage is per Batch, right? is this an average?
It's the maximum memory every used by that hash. > What is the unit measure for Bucket? There is no unit - it's just how many buckets. > there are 14 temp files generated for this query and the only Sort > says it was on memory so these files should come from the hashes, can > we say that in the explain analyze? I think maybe it's 2 temp files per batch in excess of 1, thus (8 - 1) x 2 = 14 for the 8-batch join and none for the other two. Perhaps you'd care to test that hypothesis? > mmm... that memory usage, could be > Disk actually? No. ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
