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Handling large data sets for web apps
Message
De
01/08/2001 12:22:17
 
 
À
01/08/2001 11:46:52
Information générale
Forum:
Visual FoxPro
Catégorie:
West Wind Web Connection
Divers
Thread ID:
00535271
Message ID:
00538371
Vues:
8
>Dan,
>
>SNIP
>>
>>Those are good ideas. I also think it would be nice to have in the select a NoOptimize per clause. In that way you could keep your indexes, because clearly there are times that even when returning a large set, you still need the index.
>>
>>You had also said something about a FORCE in VFP 7.0. Can you talk a little more about what exactly the FORCE does?
>
>Here's an extract form the new SQP - Select command:
>"FROM
>Lists the tables containing the data that the query retrieves. If no table is open, Visual FoxPro displays the Open dialog box so you can specify the file location.
>Once open, the table remains open once the query is complete.
>FORCE specifies that tables are joined in the order in which they appear in the FROM clause.
>If FORCE is omitted, Visual FoxPro attempts to optimize the query.
>However, the query might be executed faster by including the FORCE keyword to disable the Visual FoxPro query optimization.
"
>
>A 'nooptimize' option per clause expression is a good idea too.
>
>Thinking more about this I figure that the VFP Team could at least do something simple, even if it is only ever 'rule based' optimization... it could have a "rule" to examine the actual index content for any expression and if the number of initial nodes is few, especially as compared to the number of records in the table, it could bypass that index (maybe even if only not on a local table).
>
>Cheers

Sounds good. Thanks for the info.
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