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What data is transmitted across the network?
Message
De
14/08/2003 10:26:49
Hilmar Zonneveld
Independent Consultant
Cochabamba, Bolivie
 
 
À
13/08/2003 21:20:56
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00820001
Message ID:
00820135
Vues:
21
>Hi all,
>
>I have a question regarding VFP's performance across a local area network as to how it handles data transfer between the client and server computers.
>
>In our case, we have a 501 MB (2,000,000+ rows) table sitting on a server. Our application does not open the table directly but uses a local parameterized view to extract data.
>
>My question is: When our application issues a tableupdate() in optimistic row-buffering mode, I know VFP opens the base table and the corresponding CDX file, does VFP 'gets' the base table data with the index to the client machine to issue the update? Is the entire base table with CDX 'transferred' across the network?
>
>Any feedbacks, comments or links highly appreciated.

VFP will transfer any records you require. Also, VFP will transfer any data required from an index. For instance, to do a SEEK on a table of 1 million records, VFP might have to look at approximately 20 index keys (log(2) 1,000,000).

Also, for Rushmore Optimization, VFP will get data for several records that match search criteria. For instance, an index on deleted() might force VFP to get almost the entire index over the network, or from the local disk, for the "optimization" process. IOW, an overly aggresive optimization strategy can be counterproductive in some cases.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
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