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Any way to speed this up
Message
De
25/10/2007 15:14:56
 
 
À
25/10/2007 08:59:31
Information générale
Forum:
Visual FoxPro
Catégorie:
Codage, syntaxe et commandes
Divers
Thread ID:
01263510
Message ID:
01263764
Vues:
20
If you have order set to something on any of the participating files in your SQL statement, that can slow it down tremendously (don't ask...). It is weird, but if you have order set on SCAN, LOCATE, REPLACE ALL, etc. data handling commands, VFP slows way down (comparatively) compared to operations with no ORDER set on any files. I've personally seen 100 -fold speed increases on large tables.

Also, look at the SQL showplan for your SQL statement. This is from VFP 9 help file:


Enables or disables display of Rushmore optimization levels for queries.


SYS(3054 [, 0 | 1 | 11 | 2 | 12] [, cMEMVAR])



Parameters
0
(Default) Disables the display of Rushmore optimization levels.

1
Enables the display of the Rushmore filter optimization levels.

11
Enables the display of Rushmore join optimization levels.

2
Includes SQL statement with the display of the Rushmore filter optimization levels.

12
Includes SQL statement with the display of Rushmore join optimization levels.

cMEMVAR
Specifies an undeclared or declared PUBLIC or LOCAL memory variable in which to store the showplan information. If you have not declared cMEMVAR, Visual FoxPro creates it as a PRIVATE variable.

Pertti Karjalainen
Product Manager
Northern Lights Software
Fairfax, CA USA
www.northernlightssoftware.com
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