Why is my ora-01555 snapshot too old?
Why is my ora-01555 snapshot too old?
This message appears as a result of an Oracle read consistency mechanism. While your query begins to run, the data may be simultaneously changed by other people accessing the data. Oracle cannot access the original copy of the data from when the query started, and the changes cannot be undone by Oracle as they are made.
What does the error message ora-01555 mean?
ORA-01555 Error Message “Snapshot Too Old” Error ORA-01555 contains the message, “snapshot too old.” This message appears as a result of an Oracle read consistency mechanism. While your query begins to run, the data may be simultaneously changed by other people accessing the data.
Why is the undo segment too old in Oracle?
This error is related to rollback (Oracle 8i and below) / UNDO (9i and above) segments. Oracle uses UNDO segments for maintaining the read consistency of the database by recording the block level changes to the UNDO. UNDO is used for reconstruct the read-consistent snapshot of the data.
Why is Transaction 1 disconnected with ora-1555?
So the session connected to the transaction 1 will get disconnected with ORA-1555 error because of the unavailability of read consistent snapshot data. For oracle 8i and below increase the number of rollback segments and use bigger rollback segments.
How to convert SQL snapshot to physical standby?
Once the testing is over we can again convert the snapshot database to physical standby. Once it is converted physical standby database, whatever changes were done to the snapshot standby will be reverted. SQL@STANDBY> select open_mode from v$database; OPEN_MODE ——————– READ ONLY WITH APPLY 1 row selected.
When does a snapshot too old error occur?
If the undo segment name is null ORA-01555: snapshot too old: rollback segment number # with name “???” too small If the segment_name or the undo segment is known the error is occurring with an UNDO segment. Why would one think that the transaction slot’s time has exceeded UNDO_RETENTION?
What does snapshot standby mean in Oracle 11g?
Snapshot standby is a feature in Oracle 11g that allows doing a read-write operation on the standby database.
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