Category Archives: Performance Tunning

Indexes

Indexes are used to speedup data access in the database. By using them one can quickly find the data in a table without having to read all the data from the tables.

The index structure resembles an inverse tree similar to a directory structure. This tree begins with the 1st page of an index which is the root node which contains pointers to other pages in the index. Then comes the intermediate node or branch node which also contains pointers to leaf nodes or other branch nodes. The leaf node is the lowest level page in an index and it contains either an Row identifier (RowId) that points to the actual data in a table or it may even contain a clustering key itself.

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