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Database Administrator's Guide

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COMMIT_LOCK_DEFER_MS

COMMIT_LOCK_DEFER_MS <defer time in milliseconds>

Provides an additional tuning mechanism for the COMMIT_READ_LOCK retry value.

The length of the defer value can be varied from zero to 100 milliseconds.

Internal tests demonstrated the effect of this change on CPU utilization was dramatic as a reader attempted to retry its read commit lock. Of course, actual performance increases will be variable, depending on any particular server environment. The trade-off with this method is introducing an unnecessary defer (i.e. if the next retry without a non-zero defer would have succeeded). In practice, this was not found to impede performance.

Commit write locks held by the transaction (i.e., locks that block read attempts during the actual commit process) are held during the entire commit. This has no direct impact upon the transaction commit, however, can cause longer delays for a read attempt when the transaction itself is comprised of a large number of write operations (e.g., committing thousands of ADDREC()s)

Default: 10

See Also

COMPATIBILITY NO_COMMIT_READ_LOCK

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