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Apply Logs on Standby System with Time Delay or Lag

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Problem Description

We would like the standby database running with a delay or lag, for example 2 hours. Long explanation(for clarification):

The primary database will transport all archive-information to the standby-Server at once =normaly. But the standby database applies the changes always 2 hours later. So, if we recognize a problem like a bad Update/delete,... we will open the standby in read only mode and read the old, correct data.

Solution

Variable: APPLY_DELAY_LAG_MINUTES

Default value: 0

Description: This creates a lag time between the archiving of a redo log at the primary database and the application of the log on the standby database.

Note: The archive logs are still transferred to the standby server as normal without delay.

To turn off APPLY_DELAY_LAG_MINUTES, set to 0.

Example

APPLY_DELAY_LAG_MINUTES=100

Note

When this variable is > 0, MAX_TIMES_TRIED can no longer be relied on to alert when there are no new archives to be applied to the standby database. Use TRANSFER_LOG_GAP_THRESHOLD instead for alerting.

Arjen Visser June 08, 2013 11:42

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