Avoiding table state ERROR as a result of a Db2 shutdown

After a shutdown of the target database service (Db2 or Db2 Warehouse), some of your Data Gate tables are in the ERROR state.

Symptoms

If you click the Table tab on the dashboard of your Data Gate instance, you can see that some of your tables are in the ERROR state, which means that you have to reload these tables.

Causes

The shutdown of the target database service interrupts the last phase of the synchronization process (table-change-apply-process). As a consequence, affected tables are set to the ERROR state.

Resolving the problem

If you know ahead of time that your target database service will be shut down, you can avoid the error state of your Data Gate tables, and thus also avoid a reloading of these tables. Follow these steps:

Before you stop the target database service, open the dashboard of your Data Gate instance, and stop synchronization by clicking the following switch:
The switch must show an operation mode of Off:

Alternatively, you can go to the command-line of the Cloud Pak for Data control plane, and run the following commands on the data-gate-api container:
```
oc exec -it ${DG_POD} -c data-gate-api -n ${PROJECT_CPD_INST_OPERANDS} -- bash
cd /head/clone-api/scripts
sh stop_replication.sh ${CP4D_USERNAME} ${CP4D_PASSWORD} ${IAM_Integration}
```
where:

DG_POD

Is the pod name of the Data Gate instance

PROJECT_CPD_INST_OPERANDS

Is the project name of the Cloud Pak for Data control plane and services

CP4D_USERNAME

Is the name that you use to log in to Cloud Pak for Data and to access the Data Gate UI

CP4D_PASSWORD

Is the password belonging to the login user name.

IAM_Integration

Is a value that indicates whether Cloud Pak for Data has been integrated with the Identity Management Service. A value of true means integrated; false means not integrated.
Stop the target database service (Db2 or Db2 Warehouse).
Finish your maintenance work on the target database.
Restart the target database service.
On the dashboard of your Data Gate instance, restart synchronization by clicking the switch so that it shows On:
Alternatively, you can run the following commands:
```
oc exec -it ${DG_POD} -c data-gate-api -n ${PROJECT_CPD_INST_OPERANDS} -- bash
cd /head/clone-api/scripts
sh start_replication.sh ${CP4D_USERNAME} ${CP4D_PASSWORD} ${IAM_Integration}
```
For a description of the parameters, see the list in step 1.