enq: TX – index contention – Oracle wait event

If you performed lot of DMLs (specially Deletes) on a table, you may have lots of empty leaf blocks in the associated indexes on that table. These empty leaf blocks are left in the b-tree structure AND attached to the freelist. On subsequent inserts, the process might need to split a block so it takes…

db file scattered read – oracle wait event

DB File scattered read wait event occurs when an oracle process waits for a physical read of multiple oracle blocks from the disk. This wait identifies that a full scan (Full Table Scan or Index fast full scan) is occurring BUT during this read the blocks are read into memory locations that are not physically…