PDB Local Undo for Each RAC Instance
Usually, we have separate undo tablespace for each instance in a RAC database. For example, UNDOTBS1 is for the first instance and UNDOTBS2 is for… Read More »PDB Local Undo for Each RAC Instance
UNDO
How to Resolve ORA-01555 UNDO_RETENTION
ORA-01555 UNDO_RETENTION Let's see the error ORA-01555 UNDO_RETENTION first: Description ORA-01555: snapshot too old: rollback segment number string with name "string" too small Cause rollback… Read More »How to Resolve ORA-01555 UNDO_RETENTION
UNDO_RETENTION, How and Why
UNDO_RETENTION At times, you may find out or feel that UNDO_RETENTION is useless at all. Raising the number of seconds cannot resolve ORA-01555. This is… Read More »UNDO_RETENTION, How and Why
How to Resolve SMON: about to recover undo segment xx SMON: mark undo segment xx as available
Repeated messages were found in the alert log after instance startup:...SMON: about to recover undo segment 32SMON: mark undo segment 32 as availableSMON: about to recover… Read More »How to Resolve SMON: about to recover undo segment xx SMON: mark undo segment xx as available
How to Resolve ORA-01562: failed to extend rollback segment number
Found repeated errors in the alert log:...ORA-01562: failed to extend rollback segment number 96...It seemed that some transactions were doing DML, but they failed to… Read More »How to Resolve ORA-01562: failed to extend rollback segment number
Oracle Undo Tablespace Usage
The first purpose of using UNDO is for storing all uncommitted data in case we need to undo uncommitted data in rollback or after system… Read More »Oracle Undo Tablespace Usage
How to Resolve ORA-30036 UNABLE TO EXTEND SEGMENT BY 8 IN UNDO TABLESPACE 'UNDOTBS1'
ORA-30036 This error ORA-30036 could be very serious in a situation that is described below and may make users panic: One day, a DBA was… Read More »How to Resolve ORA-30036 UNABLE TO EXTEND SEGMENT BY 8 IN UNDO TABLESPACE 'UNDOTBS1'