1.FTS(Full Table Scan)
2.Index lookup
3.rowid
Index lookup could be
1.index unique scan
2.index range scan
3.index full scan
4.index fast full scan
Index fast full scan is much faster compared to index full scan.
In case of index full scan, oracle scans the root, branches and leaf nodes upto bottom using single block I/O.
In case of index fast full scan, oracle uses multi I/O and scans leaf nodes skipping the root and the branches.
