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Performance Issue
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25/08/2009 12:13:03
 
 
À
25/08/2009 12:03:33
Information générale
Forum:
Visual FoxPro
Catégorie:
Problèmes
Versions des environnements
Visual FoxPro:
VFP 6 SP5
OS:
Windows XP SP2
Network:
Windows 2003 Server
Database:
Visual FoxPro
Application:
Desktop
Divers
Thread ID:
01419605
Message ID:
01420495
Vues:
90
>>> We noticed that the more indexes are in the CDX, the slower the access tends to be on a networked data.
>>
>>Opening a table that isn't already open in the VFP instance forces VFP to read the 4 KB header for each index tag. That is, opening a table with 25 indexes will transfer at least 100 KB across the network in 25 separate I/O requests that are all handled sequentially (that is, sensitive to network latency).
>
>I have two to four indexes on most tables, on integer primary or foreign keys to speed up views and queries. What's the breakpoint to determine whether it's faster to have the index or not?
>
>Chris.

No fixed rules here, only tests can give you the answer in each case.
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