This topic provides information on tuning database applications.
A DB2® Everyplace® data source accepts connections from one process at a time. When more than one process tries to connect to the same data source at the same time, the requests are put into a queue. However, DB2 Everyplace allows multiple database connections within the same process
(or address space). For example, the connect method in the java.sql.Driver interface supports ENABLE_SHARED_DATABASE_ACCESS, a Boolean property that you can set to true to enable concurrent access.
Before developing applications that use multiple connections, you should understand the following concepts.
Concurrency issues: XPD622
refers to the sharing of resources by multiple interactive users or application programs at the same time. DB2 Everyplace supports concurrent transactions, enabling an application to establish several distinct connections to the same database.
Table locking: XPD622
A lock associates a database manager resource with an application to control how other applications can access the same resource. DB2 Everyplace supports table locking
. That is, you either lock the entire table or you don't lock it at all. You cannot lock specific rows in a table.
Guidelines for locking: XPD622
This topic presents the guidelines you should consider when tuning locking for concurrency and data integrity.
Parent topic: Tuning DB2e: XPD622