To optimize database processing, an application can pool database transactions. Transaction pooling maximizes database throughput while controlling the number of database connections that can be open at one time. When you establish a transaction pool, an application can reuse connections made to the same data source.
When an application connects to a database without using transaction pooling, PowerBuilder physically terminates each database transaction for which a DISCONNECT statement is issued.
When transaction pooling is in effect, PowerBuilder logically terminates the database connections and commits any database changes, but does not physically remove them. Instead, the database connections are kept open in the transaction pool so that they can be reused for other database operations.
Transaction pooling can enhance the performance of an application that services a high volume of short transactions to the same data source.
To establish a transaction pool, you use the SetTransPool function. You can code SetTransPool anywhere in your application, as long as it is executed before the application connects to the database. A logical place to execute SetTransPool is in the application Open event.
This statement specifies that up to 16 database connections will be supported through this application, and that 12 connections will be kept open once successfully connected. When the maximum number of connections has been reached, each subsequent connection request will wait for up to 10 seconds for a connection in the pool to become available. After 10 seconds, the application will return an error:
myapp.SetTransPool (12,16,10)
For more information about the SetTransPool function, see the PowerScript Reference.
