B-tree indexes

Informix® uses a B-tree index for columns that contain built-in data types (referred to as a traditional B-tree index), columns that contain one-dimensional user-defined data types (referred to as a generic B-tree index), and values that a user-defined data type returns.

Built-in data types include character, datetime, integer, float, and so forth. For more information about built-in data types, see IBM® Informix Guide to SQL: Reference.

User-defined data types include opaque and distinct data types. For more information about user-defined data types, see IBM Informix User-Defined Routines and Data Types Developer's Guide.

The return value of a user-defined function can be a built-in or user-defined data type, but not a simple large object (TEXT or BYTE data type) or a smart large object (BLOB or CLOB data type). For more information about how to use functional indexes, see Using a functional index.

For information about how to estimate B-tree index size, see Estimating index pages.

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