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3-34 IBM Informix OnLine Database Server Administrator’s Guide
Change the Logging Status of a Database
Adding Logging to a Database
Unbuffered logging is the best choice for most databases. In the event of a
failure, only the single alteration in progress at the time of the failure is lost.
If you use buffered logging and a failure occurs, you could lose more than
just the current transaction. In return for this risk, performance during alter-
ations is slightly improved.
Buffered logging is best for databases that are updated frequently (so that
speed of updating is important) as long as you can re-create the updates from
other data in the event of failure.
If you are working in a single-tape-drive environment without an easy way
to ensure that logical log files do not fill during an archive, you might need
to create your level-0 archive in quiescent mode.
If this is the case, you must create the level-0 archive from within
DB-Monitor.
If you use the command-line option to create an archive, the flag indicating
that you created the necessary archive is reset as soon as you enter
DB-Monitor to change the logging status. DB-Monitor requires you to redo the
archive.
From DB-Monitor
Follow these steps to add logging to a database:
1. Take OnLine to quiescent mode. (Refer to page 3-10.)
2. Create a level-0 archive from DB-Monitor. (Refer to page 3-57.)
3. Select the Logical-Logs menu, Databases option. Specify the
database and add logging, following the screen directions. (This is
described in the following paragraphs.)
From the Command Line
If you can create an online archive and wish to do so from the command line,
you can save yourself a step and request the change in logging status as part
of the same command. However, the drawback is that the database remains
locked for the duration of the level-0 archive. Users cannot access it.