Basically GG keeps a pointer to the oldest open transaction in the redo/archive logs -- which could be very, very old if someone starts a Toad session, locks their screen & goes on vacation for two weeks. GG doesn't know if that transaction will eventually contain an operation that GG needs to capture. If "extract" is stopped and restarted, it basically has to re-read the entire archive/redo logs from this oldest "begin transaction" pointer, and the archived logs have been removed. In the extract report, user would get 'no valid default archive xxxx' error.
In order to prevent this issue from arising, please add 'WarnLongTrans' in the extract parameter files. For instance:
WarnLongTrans 2dh CheckInterval 5m
To fix the issue. Run 'info extract xxx showch' to see the oldest and current sequence#, RBA. Depending on your scenario, you could:
1. Alter extract xxx begin / to let the extract start extracting from designated time/now on.
2. Ignore the open transaction.
SEND EXTRACT xxx, SHOWTRANS
SEND EXTRACT xxx, SKIPTRANS
3. ALTER EXTRACT xxx EXTSEQNO X, EXTRBA Y to reset extract to designated seq# and RBA#.
ALTER EXTRACT xxx, BEGIN NOW
Note: these two methods cause data lose.
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