Plateforme Level Extreme
Abonnement
Profil corporatif
Produits & Services
Support
Légal
English
JVP, flexibility of databases
Message
De
22/11/2003 18:45:57
 
 
À
22/11/2003 08:08:14
Walter Meester
HoogkarspelPays-Bas
Information générale
Forum:
Visual FoxPro
Catégorie:
Autre
Divers
Thread ID:
00851534
Message ID:
00852698
Vues:
26
>Rod,
>
>>FWIW, the SQL Select command based on a key value will perform as fast as a seek command.
>>Take a look at foxforum.com
>
>I have a real trouble believing this when knowing how this is implemented. Fact is that in any SQL server database the external scheme is seperated from its implementation. The seek is a very effictive command by directly using the index without relying on an optimizer and its overhead.
>
>>Click on the last 3, 7 or 30 days option. It's actually calling this for each topic that comes up
>
>I will do a test myself when I´ve got the time and report it up here.
>
>Walter

Well, you can't compare the SELECT to a SEEK, you are correct...

SEEK works on an already open table with an existing index set. So, many of the records are buffered already, and perhaps the index is too. The closest comparison you might be able to get to was from a fresh reboot compare...

USE Table
SET INDEX TO
SEEK

To

SELECT pk FROM table where pk=1

Even that isn't a true test, cause the select has to be sent to the back end, and the result has to be returned... this is cause SEEK and SELECT don't really do the same think...

SEEK sets the current record to a record that matches the seek value in the table.

SELECT locates the correct record, creats a result set and returns it.
Précédent
Suivant
Répondre
Fil
Voir

Click here to load this message in the networking platform