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Behavior of Local View (read-only) when data is updated
Message
 
 
À
08/08/2000 15:49:18
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00402442
Message ID:
00402476
Vues:
12
>SET REFRESH only applies to browse windows on cursors that other people can update. Since no one else is making changes to a view that you have used, there's really nothing to refresh.
>In order to get data changes into the view, you'll have to REQUERY() the view.
>

It's actually a combination of both. SET REFRESH also refreshes the cached data on your workstation using the data stored on a network. If you issue a REQUERY() and someone else has changed the data, then the requery may not pick up those changes.

The default value for SET REFRESH is 5 seconds and for most applications this is okay. The key issues to watch out for are network performance and concurrency. If you have to have up-to-date data, can your network handle the load of constantly querying the server to get the latest data? If your network is slow, will your end user allow for data to be minutes out-of-date? It's one of the things every developer needs to address for every application and it changes for every application.

Just another note. For whatever reason, sometimes SET REFRESH does not work in private datasessions when the same tables are open in the default datasession. To get around this, you can get an RLOCK() and immediately release it to update the local data buffer.

*snip*
Larry Miller
MCSD
LWMiller3@verizon.net

Accumulate learning by study, understand what you learn by questioning. -- Mingjiao
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