This list describes the amount of time that is required by Oracle to perform a query. The fastest row access by ROWID happens very quickly since
Oracle knows the exact data block where the row resides. The slowest, a full-table scan, could take hours to execute, depending upon the number of
rows in the table.
The following list reflects the fastest to slowest time required to perform a query:
- Single row access by ROWID
- Single row by cluster join
- Single row by hash cluster with unique or primary key
- Single row by unique or primary key
- Cluster join
- Hash cluster key
- Indexed cluster key
- Using a multi-column (concatenated) index
- Using a single column index
- A bounded index range scan
- A full-table scan