Could some experts in this forum explain what is the concept of slot in relationship to the rollback segment. I was told by a senior DBA and when in doubt, drop and recreate the rollback segments in stead of alter the storage due to the issue with slot allocation. Could someone comment on /explain this?
For each rollback segment, there is a transaction table. This contains pointers to the extent containing information for a particular transaction. These pointers (and other info) is contained in a structure referred to as a slot. The number of slots is determined by db_block_size.
Altering the storage parameters for a rollback segment will not be impacted by nor will it impact the slots in the transaction table. Dropping and recreating a rollback segment will create a new segment with the same number of slots. The main difference is that the altered rollback segment will still contain transaction data that may be needed for read consistency.