| 摘要 |
A method and apparatus using an extender for a computer-implemented relational database system is disclosed for storing, querying, and retrieving structured documents. The extender provides a new abstract data type and includes a plurality of user defined functions for storing, querying, and retrieving structured documents internally, as character-based large objects (CLOB), or externally, in flat files or URLs, for example. The extender has "conditional select" functionality, "conditional select" functionality is based on user defined functions residing within the extender being applied to a projection in a structured query in the database system. The extender also has a set of user defined functions for creating one or more indexes for structured documents stored in the relational database system using already created B+ tree index structures implemented in the database system to support the indexes. The method includes a tag counting system for indexing structured documents and for implementing the structure indexes within the relational database.
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