Re: Oracle Performance

In article <7gpivq$gns$1_at_nnrp1.dejanews.com>,   lisa.bogart_at_eds.com wrote:
> I am not an Oracle person - just an application developer - but my DBA is
> seriously overworked and I am hoping someone can give me some clues to a
> performance problem I am having. I have a select that joins together 4
> tables that each contain about 150000 - 300000 records. The select only
> returns about 55 records, however. The problem is that when I run the select
> anywhere (my app, SQP-Plus, ODBC Test) I get almost instantanious response at
> first but then after it has gottn most of the data, it chokes for over a
> minute before it gets the last few records. The problem is that I am trying
> to create a disconnected recordset in a VB component running in MTS. With a
> disconnected recordset, it gets all the data at once so my performance is
> horrible. Can anyone point me in the right direction?
>
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Without knowing which indexes there are ( if any ) and without seeing the actual query, I can only make a general comment here :

Always order the tables in your 'from' with increasing selectivity, i.e. put the table that will return the fewest rows ( based on the 'where' criteria ) last - (this is not always the table containing the fewest rows), the one that will return the most rows first. This is true only, of course, if you use the rule-based optimizer.

HTH
--
Oliver Willandsen - [European Commission - http://europa.eu.int]

All comments represent my own opinion and may not in any circumstance be regarded as stating an official position of the European Commission

-----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own Received on Wed May 05 1999 - 10:05:43 CDT