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Set Exclusive or LockTable? |
Wed, Aug 31 2011 8:59 AM | Permanent Link |
marcioehrlich | I'm quite confused about the practical difference between setting a table to exclusive or locking it. This is what the manual says:
EXCLUSIVE: When the Exclusive property is set to True and the application successfully opens the table, no other application can access the table. LOCKTABLE: Call the LockTable method to lock all of the records in a table and prevent other sessions from placing a record lock or table lock on the table. It looks like pretty the same to me. When should I really use each method? Tks, Marcio |
Wed, Aug 31 2011 9:30 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | marcioehrlich
Opening a table exclusive stops anyone else from even opening the table, locking the table simply prevents them updating the table. Some operations (eg table restructure) require exclusive access to a table, just locking the records wouldn't be sufficient. I've tended to use EXCLUSIVE when I want to carry out operations where other users shouldn't even be in the app whilst they're running and I didn't want to use a transaction because I wanted to be sure the operation ran and completed. Once I've grabbed the table with EXCLUSIVE that's it no one else can even open it. Roy Lambert [Team Elevate] |
Wed, Aug 31 2011 12:48 PM | Permanent Link |
marcioehrlich | Thanks a lot, Roy.
When using queries to update or insert, how does that work? I haven't seen examples at the manual. Tks. Marcio Roy Lambert wrote: Opening a table exclusive stops anyone else from even opening the table, locking the table simply prevents them updating the table. |
Wed, Aug 31 2011 6:55 PM | Permanent Link |
Jose Eduardo Helminsky HPro Informatica | Marcio
<< When using queries to update or insert, how does that work? I haven't seen examples at the manual. >> Just think the engine need to open the table related with query, perform the operation (insert, update or delete) and then close the table. If there are others users with this table opened exclusively, when query needs to open the table it will fail. As a general idea, queries are wrappers to access the tables. Eduardo |
Thu, Sep 1 2011 3:14 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | marcioehrlich
You wouldn't use either when using SQL you'd use transactions. Look at section 2.12 Transactions in the PDF manual Roy Lambert [Team Elevate] |
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