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Transaction Management
4.1 Overview
4.1.2 Transaction State Changes
There are eight valid state changes allowed for the
SET TRANSACTION
command.
Attempting to change transaction state to a state that is not allowed produces
an error message of
%RTR-E-INVSTATCHANGE, Invalid to change from current
state to the specified state
. The Table 6–19 table identifies the valid state
changes.
Table 4–19 Valid Transaction State Transitions
NEW STATE
Current State COMMIT ABORT EXCEPTION DONE
SENDING YES
VOTED YES YES
COMMIT YES YES
EXCEPTION YES YES
PRI_DONE YES
Four typical situations are listed below where transaction state changes by the
system administrator are allowed.
1. State
SENDING
changed to state
ABORT
.
The application server, after receiving a
rtr_mt_msg_1
message and before
calling
rtr_accept_tx( )
for a particular transaction, experiences a ‘‘hung’’
situation and cannot proceed. Aborting this transaction with the
SET
TRANSACTION
command is the only way to correct it. Internally, RTRACP
will send the ABORT message to the router as well as the all participating
servers to abort this transaction in a consistent matter.
2. State
VOTED
changed to state
COMMIT
.
This is the case where a application server running on the backend may
have been separated from the rest of participating servers after casting the
VOTE for the transaction. The other servers may have already committed
the transaction but not ‘‘forgotten’’ it. As far as the application is concerned,
this global transaction is committed and all changes have been committed to
the underlying database on the different sites. However, the local transaction
record is still in VOTED state in the RTR journal. You can use the command
to manually commit the local transaction branch.
Note that this command is only applicable if there is no coordinating router
running, i.e., servers are separated from the rest of the RTR network. If this
is not the case, RTR rejects the command.
3. State
VOTED
changed to state
ABORT
.
In a similar manner to the VOTED-to-COMMIT situation described above,
the server has been separated from the other participating servers and all
other participants aborted this transaction; use this command to manually
abort the local transaction branch.
Note that this command is only applicable if there is no coordinating router
running and servers are separated from the rest of the RTR network. If this
is not the case, RTR rejects the command.
4. State
COMMIT
changed to state
DONE
.
Transaction Management 4–3