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Views - Speed issues
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03/11/2003 19:32:08
Todd Cottengim
Alpine Land Information Services
Redding, Californie, États-Unis
 
 
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Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Titre:
Views - Speed issues
Divers
Thread ID:
00845866
Message ID:
00845866
Vues:
56
I know this has been posted already but I am still looking for answers.

Assume the following table:
PLOTS: 300K records and the possibility of 1.5M records. Index on field "plot_id".

cFilter: 1 TO RECCOUNT("plots") records. Index on field "linkfield"

View appear to be a great tool when used with a simple where.
WHERE plot_id = ?lnPlotId)
The abopve returns one record. No more, no less. And in under .01 seconds.

But what if your WHERE isn't quite so simple?
WHERE plot_id IN (SELECT linkfield FROM cFilter)
OR
WHERE EXITS (SELECT linkfield FROM cFilter)
OR even change the WHERE to a JOIN
JOIN cFilter ON plots.plot_id = cFilter.linkfield
Select times can run up to 20 minutes in a logrithmic type curve.

SET DELETED is OFF
All indexes appear proper.
SYS(3045,11) indicates that rushmore if full when it should be (example #1) and none in examples 2 and 3. On example 4, SYS(3045,11) returns joining table x to table y on index z.

Anyone have any thoughts?

TC
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