[AccessD] UNION slowness

Gustav Brock Gustav at cactus.dk
Mon Mar 15 10:01:50 CDT 2010


Hi John

How about using UNION ALL? Without the ALL it performs a default DISTINCT which may be very slow.

/gustav


>>> jwcolby at colbyconsulting.com 15-03-2010 15:51 >>>
I have always done a UNION to get a combo list with *; All as the first item in a combo of other 
items.  PKID, Client or PKID, Product etc.

These unions are takling as looooooong time (many seconds) when going against a SQL database.  Not 
sure why because the actual data itself is almost instant, it is just when unioned with my other 
piece it takes forever to get the result set.  Strange.

I could do a custom callback but it takes me forever to figure out the callback crap, and I just 
generally hate them.

I wanted to do a value list since the lists are short, but AFAICT the list value function has to be 
interpreted and dumped in to the property in OnEnter and the like.  Clumsey, particularly when one 
combo depends on (is filtered by) another list (products filtered by client etc).

Any words of wisdom on this?  Something I have forgotten or never knew?

-- 
John W. Colby
www.ColbyConsulting.com 





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