Re: Slow Query Performance from the Web

[Simon Coulter <shc@xxxxxxxxxxxxxxxxx>]

On 20/04/2006, at 7:19 AM, Corissa Andrascik wrote:

>  I still don't understand the reason why it made such a huge difference
> when running on the web compared to the 400

Probably because the default for interactive SQL is OPTIMIZE(*FIRSTIO) 
so as soon as it has fetched enough records to fill a screen you see 
the result. Batch is usually OPTIMIZE(*ALLIO) so the entire query has 
to finish before you see the results. Try paging down in interactive 
SQL and see if the Query running message appears each time. If so then 
the query is being completed as you request additional pages of data.

> - but running it from the
> web we needed to have it ordered so that the criteria in the where
> clause were progressively LESS unique.  Does that make sense?

Of course. You are filtering on the most unique data first which is 
bound to improve things. SQL can often reorder the selection criteria 
to minimise effort but you know more about your data than SQL does.

Regards,
Simon Coulter.
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