Re: Query performance: DivideAndConquer vs. BruteForce

David Williams doodled thusly:

>>
>
> With complex subqueries, where exists and where not in's
> with outer joins?
>

very much so. one dynamic view, three unions, three subqueries on each union. around 11 tables per union. ah, yes: one subquery on the column list as well.
not a major problem at all in Oracle, provided all PK/FK indexing is in place and there are reasonably fresh stats for the optimizer to use.

of course if the result set was in the millions of rows, things would slow down. but that has nothing to do with query efficiency and all to do with result set data volumes. all this query is doing is pulling out about 100 rows out of a few hundred thousand on each table.

Cheers
Nuno Souto
nsouto_at_optushome.com.au.nospam Received on Wed Jan 09 2002 - 12:52:32 CET