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keys and base table data, manages the pages where data is stored. The portion consisting of pages in which data is
stored is called the data part for the index part.
If ADDRESS is specified as the base expression for the DSO definition, the table record storage address is used as
information corresponding to the base table data. If KEY is specified, the cluster key is used.
If data cannot fit in a given page of the data part, the SymfoWARE/RDB system automatically creates a new page.
The SymfoWARE/RDB system then divides the data between the new page and the original page for storage (called
page splitting). Index part page splitting may be performed together with data part page splitting.
If the index key is not a unique key, multiple base table data correspondence information values may exist for a single
index key value. This multiplicity (number of base table data correspondence information values), which also depends
on the index key values, is not fixed. Therefore, the BTREE structure groups index keys and base table data
correspondence information for management. Ascending order is guaranteed for these key groups. Also, to improve
storage efficiency, the system performs front compression for the index key portion.
Figure: Overview of BTREE structure shows an overview of the BTREE structure, using the STOCK table as an
example. In this example, an index is assumed to be defined for the WHCODE column, and the table storage
structure is assumed to be a SEQUENTIAL structure.
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