Recovering indoubt transactions on the host when Db2 Connect has the Db2 Syncpoint Manager configured

If your application has accessed a host or System i database server during a transaction, there are some differences in how indoubt transactions are recovered. To access host or System i database servers, Db2 Connect is used. The recovery steps differ if Db2 Connect has the Db2 Syncpoint Manager configured.

About this task

The recovery of indoubt transactions at host or System i servers is normally performed automatically by the Transaction Manager (TM) and the Db2 Syncpoint Manager (SPM). An indoubt transaction at a host or System i server does not hold any resources at the local Db2 location, but does hold resources at the host or System i server as long as the transaction is indoubt at that location. If the administrator of the host or System i server determines that a heuristic decision must be made, then the administrator might contact the local Db2 database administrator (for example via telephone) to determine whether to commit or roll back the transaction at the host or System i server. If this occurs, the LIST DRDA INDOUBT TRANSACTIONS command can be used to determine the state of the transaction at the Db2 Connect instance.

Procedure

The following steps can be used as a guideline for most situations involving an SNA communications environment:

Connect to the SPM.

For example:

db2 => connect to db2spm

Database Connection Information

Database product       = SPM0500
SQL authorization ID   = CRUS
Local database alias   = DB2SPM

Issue the LIST DRDA INDOUBT TRANSACTIONS command to display the indoubt transactions known to the SPM.
The following example shows one indoubt transaction known to the SPM. The db_name is the local alias for the host or System i server. The partner_lu is the fully qualified luname of the host or System i server. This provides the best identification of the host or System i server, and should be provided by the caller from the host or System i server. The luwid provides a unique identifier for a transaction and is available at all hosts and System i servers. If the transaction in question is displayed, then the uow_status field can be used to determine the outcome of the transaction if the value is C (commit) or R (rollback). If you issue the LIST DRDA INDOUBT TRANSACTIONS command with the WITH PROMPTING parameter, you can commit, roll back, or forget the transaction interactively.
```
db2 => list drda indoubt transactions
DRDA Indoubt Transactions:
1.db_name: DBAS3    db_alias: DBAS3    role: AR
  uow_status: C  partner_status: I  partner_lu: USIBMSY.SY12DQA
corr_tok: USIBMST.STB3327L
luwid: USIBMST.STB3327.305DFDA5DC00.0001
xid: 53514C2000000017 00000000544D4442 0000000000305DFD A63055E962000000
     00035F
```
If an indoubt transaction for the partner_lu and for the luwid is not displayed, or if the LIST DRDA INDOUBT TRANSACTIONS command returns as follows, then the transaction was rolled back.
```
db2 => list drda indoubt transactions
SQL1251W  No data returned for heuristic query.
```

What to do next

There is another unlikely but possible situation that can occur. If an indoubt transaction with the proper luwid for the partner_lu is displayed, but the uow_status is "I", the SPM does not know whether the transaction is to be committed or rolled back. In this situation, you should use the WITH PROMPTING parameter to either commit or roll back the transaction on the Db2 Connect workstation. Then allow Db2 Connect to resynchronize with the host or System i server based on the heuristic decision.