Hello,
We upgraded from 11gR2 to 12cR1.
We have 300GB of undo and 28800 undo retention
SQL> show parameter undo
NAME TYPE VALUE
------------------------------------
-------------------------------- -----------------
temp_undo_enabled boolean FALSE
undo_management string AUTO
undo_retention integer 28800
undo_tablespace string UNDOTBS
There is a particular query using a table say t1 with 540,453,510 rows and 20 indexes in 11g. It was not performing very well during 12cR1 upgrade test so that I created the following index
Idx_new (col1,col2,col3,col4) compress 3;
Instead of the existing index
Idx_old (col1,col2,col3)
I put the idx_old index invisible
The added column col4 in the new index allowed the query to do not filter anymore on table t1
However, since we went live in PROD, and after a couple of days of successful execution of that query it started failing with ORA-01555
Do you think that adding an index can provoke this new situation?
What do you suggest?
Thanks