Implicit commit and rollback operations

In some instances a commit or rollback operation is initiated by the system for a commitment definition. These types of commit and rollback operations are known as implicit commit and rollback requests.

Typically, a commit or rollback operation is initiated from an application program using one of the available programming languages that supports commitment control. These types of commit and rollback operations are known as explicit commit and rollback requests.

The following two tables show what the system does when certain events occur related to a commitment definition that has pending changes. A commitment definition has pending changes if any of the following conditions is true:

Any committable resource has been updated.
A database file opened under commitment control has been read because reading a file changes the file position.
The commitment definition has an API resource. Because changes to API resources are done by a user program, the system must assume that all API resources have pending changes.

The C CM (commit operation) journal entry and C RB (rollback operation) journal entry indicate whether the operation was explicit or implicit.

The following table shows the actions the system takes when a job ends, either normally or abnormally, based on the following situations:

The state of the transaction.
The action-if-end job value for the commitment definition.
Whether an API resource is the last agent.

State	Last agent API	Action if Endjob¹ option	Commit or rollback operation
RST	N/A	N/A	If the commitment definition is not associated with an X/Open global transaction, an implicit rollback is performed. If the commitment definition is associated with an X/Open global transaction, the following events occur: If the transaction branch state is not Active (S1), no action is performed and the transaction branch is left in the same state. If the transaction branch state is Active (S1), an implicit rollback is performed.
PIP	N/A	N/A	If the commitment definition is not associated with an X/Open global transaction, an implicit rollback is performed. If the commitment definition is associated with an X/Open global transaction, the transaction branch is in the Idle (S2) state, and it is left in the Idle (S2) state.
PRP	N/A	WAIT	If the commitment definition is not associated with an X/Open² global transaction, the following occurs: Resynchronization is started to receive the decision from the initiator of the commit operation. The returned decision to commit or rollback is performed. It is considered an explicit operation.
PRP	N/A	C	If the commitment definition is not associated with an X/Open² global transaction, an implicit commit operation is performed.
PRP	N/A	R	If the commitment definition is not associated with an X/Open global transaction, an implicit rollback operation is performed. If the commitment definition is associated with an X/Open global transaction, the following occurs: If the job that started the transaction ends, the transaction is left in a prepared state until the XA TM either commits it or rolls it back. The XA transaction branch state will be left at Prepared (S3) in this case. If the SQL server job that the transaction's work is being routed to is ended, a forced rollback is implicitly performed. The XA transaction branch state will be changed to Heuristically Completed (S5) in this case.
CIP	N/A	N/A	An explicit commit operation is performed.
LAP	NO	WAIT	1. Resynchronization to the last agent is used to retrieve the decision to commit or to roll back.
LAP	NO	WAIT	2. The returned decision to commit or to roll back is performed. It is considered an explicit operation.
LAP	YES	WAIT	1. The last agent API is called to retrieve the commit or rollback decision.
LAP	YES	WAIT	2. The commit or rollback operation is performed. It is considered an explicit operation.
LAP	N/A	C	An implicit commit operation is performed.
LAP	N/A	R	An implicit rollback operation is performed.
CMT	N/A	N/A	A commit operation has already completed for this commitment definition and any downstream locations. The commit operation is complete.
VRO	N/A	N/A	The local and remote agents voted to read-only. All downstream agents must also have voted to read-only. No action is required.
RBR	N/A	N/A	A rollback operation is required. An explicit rollback operation is performed.
Note: ¹ You can change the `Action if Endjob` option with the Change Commitment Options (QTNCHGCO) API. ²If the commitment definition is associated with an X/Open global transaction, the following events occur: If the job that started the transaction ends, the transaction is left in a prepared state until the XA TM either commits it or rolls it back. The XA transaction branch state will be left at Prepared (S3) in this case. For transaction-scoped locks only, if the SQL server job that the transaction's work is being routed to is ended, a forced rollback is implicitly performed. The XA transaction branch state will be changed to Heuristically Completed (S5) in this case.

The following table shows the actions the system takes when an activation group ends and applies only to transactions with job-scoped locks. The system actions are based on the following items:

The state of the transaction. (It is always reset (RST) when an activation group ends.)
How the activation group ends-normally or abnormally.
Whether an API resource is the last agent.
Note: If an API resource is registered as the last agent, this gives control of the commit or rollback decision to the last agent. The result of the decision is considered an explicit operation

State	Last agent API	Type of end	Commit or rollback operation
RST	No	Normal	An implicit commit operation is performed. If protected conversations exist, the commitment definition will become the root initiator of the commit operation.
RST	No	Abnormal	An implicit rollback is performed.
RST	Yes	Normal	The API exit program is called. The commit or rollback operation is determined by the API.
RST	Yes	Abnormal	The API exit program is called. The commit or rollback operation is determined by the API.