A B-tree index is a kind of structure that is formed as a balanced tree with connected interleaved nodes. This tree contains a sorted copy of values and indexed columns or columns when the index is non-clustered. When an index is clustered, data rows are a leaf of index and these rows are sorted according to its index key. When SQL Server searches data, it traverses the B-tree index from its root to leaf to address rows filtered by a query.
Because a clustered B-tree index controls the order of records in a table, every record must be placed exactly to a position in accordance with the index. This is why the best practice is to design clustered indexes on small columns (for example, integer), which raise the ordering of new ...
