On Tue, Dec 04, 2007 at 11:58:55PM -0700, m h wrote:
On Dec 4, 2007 12:56 PM, m h <sesquile@gmail.com> wrote:
Since the query is confidential I can't really put it here, but I can describe it. I'm pulling stuff out of my fact table and two other dimension tables. The select clause sums a few columns, and on one sums the product of one column and the sum of a few others. The coalesce function is used to convert NULLs to 0. The where statement joins the tables using the = operator and then has two "IN" clauses. Then there is a group by (since I'm aggregating in the select) and an order by.
Any hints on how to increase performance? Do I need to tune my query or tweak other things? (Yes I know the laptop machine is not apples to apples to the vmware machine)
Am open to suggestions.
In the meantime I've done the following in an attempt to make the query faster all to no avail (ie the speed stays the same):
* Remove the calculation doing summing and coerce'ing (this was in the selection part were I guess you do not have much data left) * Change IN statement to = * Remove primary KEY for date table and join date table with between clause (actually surprised this didn't make it slower) Only if the otherside has a foreign key it would slow down.
Single column primary key's don't help, as these are handled by in memory hash tables which are created when needed (ie without influence of the user).
* Added indexes for non-PK columns I'm joining on. No difference! So your query involves many join expressions ?
Does this have something to do with the tables in the "tmp" schema? Does it make queries slower?
We never use the 'tmp' schema for columns other then really temporaries ourselfs, so I have know real data on this, but known how the queries are translated I would expect any impact. Niels
cheers,
-matt
------------------------------------------------------------------------- SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 _______________________________________________ MonetDB-users mailing list MonetDB-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/monetdb-users
-- Niels Nes, Centre for Mathematics and Computer Science (CWI) Kruislaan 413, 1098 SJ Amsterdam, The Netherlands room C0.02, phone ++31 20 592-4098, fax ++31 20 592-4312 url: http://www.cwi.nl/~niels e-mail: Niels.Nes@cwi.nl