Since the compress transaction can be large, be sure to create enough logical logs and have enough log file space to handle the transaction.

• Make sure you create enough logical logs to handle your longest transaction. Typically, when you compress a geodatabase, long transactions occur. You must back up your logical logs before you reach the long transaction high-water mark percentage defined by the LTXHWM parameter in your Informix onconfig file. You should not change either the LTXHWM or LTXEHWM without the consent of an Informix technical support expert who is familiar with the behavior of the Informix Spatial DataBlade. If a transaction fails to complete and is rolled back because it reaches the long transaction high-water mark, then you do not have enough logical logs.
• During compression of large geodatabases, the Informix database frequently runs out of available locks. To prevent this, tables are locked in exclusive mode during compress. With ArcSDE 9, compress could be run with existing user connections. To be able to compress with existing user connections, the exclusive locking during compression needs to be disabled. The USE_EXCLUSIVE_LOCKING DBTUNE parameter can be set to false to allow compress with concurrent user connections.
You can alter the value of the USE_EXCLUSIVE_LOCKING parameter with the sdedbtune alter operation. See the Administration Command Reference installed with ArcSDE for details on how to use this command.

It is possible for compress transactions to be quite large. Therefore, for Oracle databases configured with automatic undo space management, make sure the ArcSDE administrator's UNDO_POOL is not set too low and that enough undo table space exists to complete the compress operation.

If you are manually controlling the undo space using rollback statements, you should create a separate rollback table space that is large enough to hold the transactions of the compress operation and assign one rollback segment to it. The size of the table space and rollback segment required depends on the number of states that will be deleted during the compress, but as a rule of thumb, you should start with a rollback segment of at least 300 MB. However, a much larger rollback segment may be required if data edits occur often or you compress infrequently.

You will need to set the name of the rollback segment in the COMPRESS_ROLLBACK_SEGMENT storage parameter of the DEFAULTS DBTUNE configuration keyword.

NOTE: This storage parameter doesn't exist under the DEFAULTS configuration keyword until you add it. If this parameter is not set, the next available online rollback segment will be used. If the rollback segment is not large enough, the compress operation will fail since the transaction will be forced to roll back.

Oracle recommends that you use automatic undo management. Starting with Oracle9i, automatic undo management is done by allocating space in the form of an undo table space instead of allocating rollback segments of different sizes.

Tip

• If you are adding the COMPRESS_ROLLBACK_SEGMENT parameter to the DEFAULTS configuration keyword for the first time, you will need to use the sdedbtune export and import operations. If the parameter already exists under the DEFAULTS configuration keyword, you can use the sdedbtune alter operation to change its value. See the Administration Command Reference installed with ArcSDE for details on how to use the sdedbtune command.

NOTE: Applies to geodatabases created with an ArcGIS Server Enterprise license only

You need to rebuild your business tables’ clustered indexes after running a full compress, because business table fragmentation can occur with a full compress.

For information on compressing ArcSDE geodatabases for SQL Server Express, see Compressing a geodatabase on an ArcSDE database server.