Progress
Database Administration
Guide and Reference
Case Study
This case study illustrates the process of resolving a limbo transaction. It involves two databases, sports1 and sports2, located on separate machines, mach1 and mach2, respectively. Each database has two-phase commit enabled; each has a server running against it. The coordinator database is sports1.
Suppose that you start a client process on mach1 against the sports1 database and then connect to the sports2 database using this command:
After connecting, you try to run a distributed transaction.
While running this procedure, the client process is halted by a system error, and the following messages appear:
The message indicates that a limbo transaction might have occurred. You must determine whether a limbo transaction did occur, then resolve it.
You start PROMON against sports1, choose T (Transaction Control), and choose 1 (Display all entries). This screen appears, indicating that there are no limbo transactions on sports1:
If PROMON failed to run against sports1, it indicates that the server also crashed and you must use PROUTIL to determine whether any limbo transactions occurred.
After determining that no limbo transactions occurred on sports1, perform the same steps against sports2. This time, the following screen appears, indicating that a limbo transaction has occurred:
Write down the coordinator’s transaction number (indicated in the Crd-task field). The Coord field indicates that sports1 is the coordinator database for this transaction. Therefore, you must again run PROMON against sports1. This time, choose C (Coordinator Information). The following screen appears, where you enter the transaction number 61061:
The following screen appears, indicating that the transaction committed:
Since the transaction committed on the coordinator sports1, you run PROMON against sports2 and choose 1 (Resolve Limbo Transactions). The following screen appears:
Choose 2 (Commit a Limbo Transaction), and this prompt appears:
Type 15 (the user number indicated on the previous screen). The PROMON utility commits the transaction on sports2 and displays this message:
Since there are no more limbo transactions, the situation is resolved and no further action is required.
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