SQL/MX 2.x Installation and Management Guide (G06.24+, H06.03+)

Understanding and Planning SQL/MX Tables
HP NonStop SQL/MX Installation and Management Guide—523723-004
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Key-Sequenced Tree Structure
When NonStop SQL/MX reads a key-sequenced file by its clustering key, each read
operation retrieves the record containing the next sequentially higher key value. When
NonStop SQL/MX reads the file through an alternate index, each operation randomly
accesses the table.
If you do not use an index, access occurs by the clustering key. Access can begin with
the first record in the file or can be requested for only a specified range of records in
the file.
Key-Sequenced Tree Structure
Key-sequenced files are physically organized as one or more bit-map blocks and a
B-tree structure of index blocks and data blocks. Bit-map blocks within a structured file
organize the file’s free space.