Most of the data in a database is stored in structures called B* trees. B* trees enable the database system to access the rows of a table far more efficiently than other methods, for example, a sequential search.
A B* tree has several levels, from the top root level through several index levels to the lowest level, the leaf level. The storage units, in which the data is stored, are called pages.
The sort criterion for building a B* tree is the primary key. All comparisons in a B* tree use ASCII code. The comparisons are performed for all values on a character-by-character basis.
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