Access Methods

 FTS        

 Rowid Scan

 Index Unique Scan       -- When we have primary/unique key

 Index Range Scan        -- When there is no unique index

 Index Full Scan            -- When all data in index. Allways it is seqintial.

 Index Fast Full scan     -- Always it will make you db_file_multiblock_count. If this configured, then this will use instead of FS.

 Index Skip Scan            -- Even leading column not exists, still it will use index.

 Index Join Scan           -- When data is there in multiple indexes, then oracle will join the indexs to get the data.

 Index Bitmap Access     -- A bitmap index is organized as a B*-tree index but, with bitmap indexes, a single index entry uses a bitmap to point to many rows simultaneously. Each bitmap header stores start and end ROWIDs.