About Rules for Controlling the Behavior of Capture, Propagation, and Apply

An Oracle Streams replication configuration must identify what to replicate. Capture processes, synchronous captures, propagations, and apply processes are called Oracle Streams clients. Rules determine what Oracle Streams clients replicate. You can configure rules for each Oracle Streams client independently, and the rules for different Oracle Streams clients do not need to match.

Rules can be organized into rule sets, and the behavior of each Oracle Streams client is determined by the rules in the rule sets that are associated with it. You can associate a positive rule set and a negative rule set with a capture process, a propagation, and an apply process, but a synchronous capture can only have a positive rule set.

In a replication environment, an Oracle Streams client performs its task if a database change satisfies its rule sets. In general, a change satisfies the rule sets for an Oracle Streams client if no rules in the negative rule set evaluate to TRUE for the change, and at least one rule in the positive rule set evaluates to TRUE for the change. The negative rule set is always evaluated first.

Specifically, you use rule sets in an Oracle Streams replication environment to do the following:

• Specify the changes that a capture process captures from the redo log or discards. If a change found in the redo log satisfies the rule sets for a capture process, then the capture process captures the change. If a change found in the redo log does not satisfy the rule sets for a capture process, then the capture process discards the change.

• Specify the changes that a synchronous capture captures. If a data manipulation language (DML) change satisfies the rule set for a synchronous capture, then the synchronous capture captures the change immediately after the change is committed. If a DML change made to a table does not satisfy the rule set for a synchronous capture, then the synchronous capture does not capture the change.

• Specify the changes (encapsulated in LCRs) that a propagation sends from one queue to another or discards. If an LCR in a queue satisfies the rule sets for a propagation, then the propagation sends the LCR. If an LCR in a queue does not satisfy the rule sets for a propagation, then the propagation discards the LCR.

• Specify the LCRs that an apply process dequeues or discards. If an LCR in a queue satisfies the rule sets for an apply process, then the apply process dequeues and processes the LCR. If an LCR in a queue does not satisfy the rule sets for an apply process, then the apply process discards the LCR.