Databases for REAL
Database Concurrency Strategies
Issue: 8.3 (March/April 2010)
Article Description: No description available.
Article Length (in bytes): 4,812
Starting Page Number: 53
RBD Number: 8314
Resource File(s): None
Related Link(s): None
Known Limitations: None
Excerpt of article text...
If you are building multi-user database applications using REAL Studio, then you need to be aware of how to manage concurrency. There are two common ways that concurrency is managed and both have strengths and weaknesses. They are Pessimistic Concurrency Control and Optimistic Concurrency Control.
Pessimistic Concurrency Control
Pessimistic concurrency control is a very rigid way to manage database changes. Generally speaking, when a user requests to change some information in the database (usually a row), you set a database lock on the row. This lock prevents other users from being able to change the row. If another user tries to lock the rock, they will get an error. Once the first users commits their changes, the lock is released so that others may request it.
Using locking in the manner is a great way to maintain data integrity. Since you are certain that only one person at a time can edit information, there is no chance that information will be lost or overwritten.
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