SQL/MX 3.2.1 Management Manual (H06.26+, J06.15+)

is that it requires a lot of work: you need to continually keep track of all interdependent
objects, and process many tapes during recovery.
◦ If you perform collective dumps of the SQL/MX catalog and all its objects, this command
might enable faster recovery, but you must continually update the SQL OBEY (script) files
that you use to rebuild SQL/MX objects.
NOTE: You can use OBEY command files containing TMFCOM command scripts for
TMF tasks that you perform repeatedly.
Finally, before dropping any individual view or index, be sure to save a current OBEY (script)
command file to re-create the view or index. You can obtain this file by issuing the necessary
SHOWDDL commands.
Before dropping a table, run the SHOWDDL command or be sure that the
SAVE_DROPPED_TABLE_DDL attribute is ON to ensure that you can re-create the table and its
indexes as they were defined at the time of the drop.
Also, make sure that you have the following items at hand:
• Current online dumps of the objects.
• Hard copies of the TMF catalog and the object dumps, obtained with the TMFCOM INFO
DUMPS, OBEYFORM command.
Using TMF for Transaction Recovery, Database Consistency, and Database
Recovery
TMF protects SQL/MX databases by managing database transactions, monitoring database activity
through the use of audit trails, and enabling database recovery.
TMF Concepts
The use of TMF requires an understanding of these TMF elements:
• Transactions
• Audit trails
• Audit files
• Audit dumps
• Online dumps
A brief overview of these elements follows. For more information, see the TMF Planning and
Configuration Guide.
Transactions
A transaction, in general, is a multistep operation with a designated beginning and end that
changes a database. For example, a transaction for an airline reservation could include the
operations of adding a reservation to the airline passenger list, issuing a ticket, and adding the
ticket price to the accounts receivable table. Transactions associated with SQL/MX operations are
called TMF transactions because TMF manages these transactions.
A TMF transaction can span numerous database changes that affect multiple files on multiple disk
volumes and nodes. TMF can abort an incomplete transaction if a failure occurs during the
transaction to ensure consistency. Either all or none of the changes in a transaction are applied
to the database. During normal processing, TMF also maintains the necessary locks on data to
ensure consistency of the database.
48 Planning Database Security and Recovery