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View VS. Pass-through Question
Message
De
17/08/2006 10:27:33
 
 
À
17/08/2006 10:14:44
Information générale
Forum:
Visual FoxPro
Catégorie:
Codage, syntaxe et commandes
Versions des environnements
Visual FoxPro:
VFP 9 SP1
OS:
Windows XP SP2
Network:
Windows NT
Database:
MS SQL Server
Divers
Thread ID:
01146313
Message ID:
01146375
Vues:
15
>Craig, thanks for the replies. Let me make sure I understand. Are you saying that regardless if I use a "view" or "PT" - in both instances - the query is passed to the back-end server for processing in the same way? If so, I must have gotten very confused at some point because ....
>
>I was under the impression that when you run a VFP view, the 1st step is for the back-end server to send only index info to the VFP data engine from which VFP then determines the records it needs based on the index info provided by the server and then re-send the SQL statement requesting only the needed records based on data it had read from the index info. Thus, the VFP engine was doing much of the selection work on the local workstation and because of the first step of sending the index info to VFP, you were increasing the traffic over the LAN/WAN.

Don't confuse a Remote View with a Local View. An RV goes against and ODBC data srouce while an LV work directly with Fox data. With a RV, the query is passed to the back end database. With a LV, is works exactly as if you wrote the SELECT statement itself.

>
>Futher, I thought that I had heard (or read) that by using SQL Pass-through you eliminate the first set of sending index criteria to VFP from the back-end server because your are sending the "packaged" SQL statement to the server for it to process. Since all of the processing is done by the server data engine and only the requested records are sent back to VFP, you limit the traffic across the LAN/WAN.

An RV will generate the same amount of traffic as SPT, assuming both queries are coded the same.

>
>If I am totally confused on this issue, let me ask it another way. Does a view vs. a PT statement generate the same amount of traffic accross the network?
>
>Thanks for helping me sort out the differnces between views and PT.
>
>Robert Wright
Craig Berntson
MCSD, Microsoft .Net MVP, Grape City Community Influencer
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