This topic illustrates the behavior that WebSphere Message Broker expects
when a database is quiesced. A database administrator issues the quiesce instruction
on a database; it is not a function of the broker.
This topic assumes
three things about the database being quiesced:
- The database can be quiesced
- New connections to the database are blocked by the database when it is
quiescing
- Message
flows using the database eventually
become idle
The following list shows the behavior expected while a database
is quiescing:
- Tell the database to quiesce. As soon as you tell the database to quiesce,
the connections that are in use remain in use, but no new connections to the
database are allowed.
- Processing messages. Messages that are using existing connections to the
database continue to use their connections until the connections become
idle. This can take a long time if messages continue to be processed. To ensure
that messages are no longer processed, stop the message flow. Stopping the
message flow stops messages being processed and releases the database connections
that the flow was using. This ensures that the database connections that the
flow holds become idle.
- Database connections for the message flow become
idle. This causes the broker to release the connections to the user databases
that the message flow is using. When all connections
to the database from the broker and from any other applications using the
database are released, the database can complete its quiesce function.