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Recommended Settings for DB2 9.7
The following table lists the recommended settings specific to DB2 9.7:
Feature Description Value
Currently Committed
Semantics
The DB2 database used the default Cursor
Stability (CS) isolation level in all versions
until DB2 9.7. If an application changed a
row and another application tried to read
that row before the first application
committed the changes, the second
application waited until the commit.
You can now set the currently committed
semantics of the CS level, which informs
DB2 that when the second application tries
to read a locked row, it will get an image of
what the row looked like before committing
the change.
In the enhanced currently committed
semantics, only committed data is returned,
as it used to be earlier. However, now read
operation does not wait for the write
operation to release the row locks. Instead,
the read operation returns the data prior to
the start of the write operation.
The currently committed semantics is
turned on by default in the new DB 9.7
database. The new database configuration
parameter, cur_commit is used to override
this behavior.
Currently committed semantics requires
more log space for write operations. In
addition, extra space is required for logging
the first update of a data row during a
transaction, which can have an insignificant
or measurable impact on the total log space
used.
Recommended value:
ON
42 Sterling B2B Integrator: Performance Management