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SELECT faster with SET EXCLUSIVE
Message
De
02/08/1996 02:42:05
 
Information générale
Forum:
Visual FoxPro
Catégorie:
Codage, syntaxe et commandes
Divers
Thread ID:
00004967
Message ID:
00004970
Vues:
30
>When set exclusive in on, my SELECTS execute almost exactly
>10 times faster than with the tables opened shared Why? I want the speed, but need to share as well.
>
>I ran a program to try about 30 equal size selects, ran this
>with exclusive on and off and the results averaged about 0.7 sec with exclusive (max 1.7 min .49). With shared it averaged about 7 sec (max 25 sec, min .89 sec). What's going on?

if the files are used EXCLUSIVEly fox just locks the whole table
but if the use is SHAREd it has to lock each record when he reads it

this is btw, one of the reasons that sometimes it is faster to
"take apart" an SQL statement to several queries

Arnon
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