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Standby database gap (or how much it is lagging behind the primary) can be done in two ways:
Information from Last applied Archivelog Job
Log gap report
Note that both values are independent on each other.
A. Information from Last applied Archivelog Job
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It is updated automatically by the apply job.
B. Log Gap Report
User has the possibility to run log gap report, which will check the recovery status of standby database. This report can bne initiated by running “View Detailed Log gap Report” (1) from the ACTIONS right pane:
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