In our previous blog, we have talked about the optimizer access path. In the last few blogs, we have explained different access paths. In this blog, we will see how the index unique scan works.
Index unique scan is the optimizer access path where the database returns at most one row.
It reads the index in order for specified key and stops processing as soon as it gets first record. This is simply because no second record is possible. It obtains the rowid from index and retrieve the row specified using the rowid.
In our example, we have created a primary key on column empno which in turns creates unique index on this column.