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Product Environment 9-51
Determining Database Consistency
Determining Database Consistency
This section describes the administrative procedure that might be required if
a database server process or transaction is killed after it has entered the
second phase of the two-phase commit protocol. You must perform this
procedure if one of the following two scenarios has occurred:
■ A heuristic decision to roll back occurred at a participant OnLine
after the coordinator received an acknowledgment from this partic-
ipant that it was able to commit and the coordinator later instructed
all participants to commit.
■ You, as administrator, executed the tbmode -Zoption at a participant
OnLine to initiate a heuristic end-transaction after this participant
sent an acknowledgment that it was able to commit.
Under normal processing, the need to perform this determination should
occur rarely, if at all.
Administrators are strongly advised to avoid this situation. Do not kill a
database server process or transaction after it has entered the second phase of the two-
phase commit protocol unless it is absolutely necessary.
There are five steps to determine database consistency and correct the
situation, if required:
1. Determine which participating OnLine database servers committed
a heuristic decision.
2. Determine if the networked database system contains inconsistent
data.
3. Decide if action to correct the situation is required.
4. Decide if you need to roll back the transaction where it committed,
or recommit the transaction where it rolled back.
5. Implement the decision manually through inspection of the logical
logs at each affected OnLine.