Plateforme Level Extreme
Abonnement
Profil corporatif
Produits & Services
Support
Légal
English
Is it reasonable to have index on DELETED()?
Message
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00196021
Message ID:
00198005
Vues:
64
>Hello Andrus,
> If you have a large table and you SET DELETED ON, then you need the index on DELETED() regardless of how many records are deleted. If you do not have an index on DELETED(), VFP has to inspect each record to determine whether or not to present it. Thus, you lose all Rushmore optimization.

In a partial defense of Andrus, I've run test cases where Partial Opt. ran faster than Full Opt., particularly when you have an index on Deleted and there are no deleted records, and tables are not great in size. "Full" is a theoretical label, and not necessarily always true in practice...

But to critique Andrus, try randomly deleting about 1/2 the records, and then test with and without index on Deleted, see what kind of results you get, especially with larger tables...you should find a time curve increasingly in favor of the index on Deleted as size grows (and # deleted records)...so if there's any possibility a table will ever grow "large," the index is usually a good idea...
The Anonymous Bureaucrat,
and frankly, quite content not to be
a member of either major US political party.
Précédent
Suivant
Répondre
Fil
Voir

Click here to load this message in the networking platform