By default, the transaction coordination service is always enabled. The System Administrator can enable or disable these services using the enable xact coordination configuration parameter. See the System Administration Guide for a complete description of this parameter.
The System Administrator must also ensure that Adaptive Server has the required resources to coordinate all of the RPCs and CIS updates that may be requested by transactions. Each time a transaction issues an RPC or CIS update, the transaction coordinator must obtain a free DTX participant. A DTX participant or “distributed transaction participant” is an internal memory structure that Adaptive Server uses to coordinate a transaction that has been propagated to a subordinate Adaptive Server. In Figure 3-1 ASE1 requires 3 free DTX participants, and ASE2 requires 2 free DTX participants. (In each case, a single DTX participant is used to coordinate the local work of the transaction that is propagated.
DTX participant resources remain in use by the coordinating Adaptive Server until the associated remote transaction has committed. This generally occurs some period of time after the initiating transaction has committed, since the initiating transaction commits as soon as all subordinate transactions have successfully prepared their work.
If no DTX participants are available, RPC requests and CIS update requests cannot proceed and the transaction is aborted.
