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FAQ: Can I stop or kill a compress operation after it has been started?

Question

Can I stop or kill a compress operation after it has been started?

Answer

The ArcSDE compress operation can be stopped or killed while it is executing. The operation is designed to be transactionally consistent. Implying if the operation encounters an error, fails or abruptly stops the versioned tables being compressed are still 'logically' correct with respect to any version's representation.

The compress operation first scans into memory the instance's state tree configuration. Based upon this information, the first step compress performs is to delete all states which do not participate within a version's lineage. The deletion of the state deletes all the rows from the delta tables that are associated with the state being deleted.

The next step the compress operation performs is to collapse any candidate lineage of states into one state. A candidate lineage is a collection of states that can be compressed into one state without affecting the logical representation for any table in a given version.

The final step, when applicable, is to move rows from the delta tables into the base tables.

For each step of the operation, database transactions are started and stopped for each table being compressed. The transaction verifies each table is consistent during each step of the process.

An example why one might want to stop a compress operation is, if the compress has been running for an extend period of time it might be preventing users from connecting to the instance, prior to ArcSDE release 9, or the compress operation is consuming a large amount of system resources.