MAX_COMMIT_PROPAGATION_DELAY
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Caution:
Change this parameter only when it is absolutely necessary to see the most current version of the database when performing a query. |
MAX_COMMIT_PROPAGATION_DELAY is a Real Application Clusters parameter. This initialization parameter should not be changed except under a limited set of circumstances specific to the cluster database.
This parameter specifies the maximum amount of time allowed before the system change number (SCN) held in the SGA of an instance is refreshed by the log writer process (LGWR). It determines whether the local SCN should be refreshed from the lock value when getting the snapshot SCN for a query. Units are in hundredths of seconds.
Under very unusual circumstances involving rapid updates and queries of the same data from different instances, the SCN might not be refreshed in a timely manner. Setting the parameter to zero causes the SCN to be refreshed immediately after a commit. The default value (700 hundredths of a second, or seven seconds) is an upper bound that allows the preferred existing high performance mechanism to remain in place.
