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Rushmore SQL Optimization
Message
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00761335
Message ID:
00761412
Vues:
41
>>Be careful. It is my experience that an index on deleted() can make local queries (not over a network), and with few records, faster; but the same query over a network, and with many more records, might actually get slower. Before deciding to keep the index on deleted(), you should test under real-life circumstances, for instance, over a network and with the number of records you expect to have in the near future.
>
>Really? I haven't encountered this -- under what circumstances is this the case?


He refers to a situation first reported by Chris Probst in his article "Rushmore - Less Is More" in FoxPro Advisor - May 1999.

More info:
http://fox.wikis.com/wc.dll?Wiki~RushMore~VFP
http://fox.wikis.com/wc.dll?Wiki~NonDiscriminatingIndex~VFP
http://fox.wikis.com/wc.dll?Wiki~UnderstandingRushmore~VFP
http://fox.wikis.com/wc.dll?Wiki~NonMachineCollation~VFP

Universal Thread:
UT FAQ #830
UT Thread #633629
UT Message #612662

Here's the original article from Chris Probst (needs subscription)
http://www.advisor.com/Articles.nsf/aid/PROBC01

Here's an excellent analysis and explanation by Christof Lange [MVP] (needs subscription)
http://www.advisor.com/Articles.nsf/aid/GRANL21


Alex Feldstein, MCP, Microsoft MVP
VFP Tips: English - Spanish
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