Reference Work Entry

Encyclopedia of Database Systems

pp 2857-2862

Structure Indexing

  • Mariano P. ConsensAffiliated withUniversity of Toronto


Structural index; Structural summary; Path index; Dataguide; Synopsis; Sketch


Structure indexing creates summaries of the structure present in semi-structured data collections by grouping data items with similar structure, providing a mechanism to index such items. Since semi-structured data models are commonly represented by labeled graphs or trees (the XML data model being a prime example), structural indexes or summaries are naturally described as graphs where nodes represent sets of data items (called extents), and where edges represent structural relationships between the corresponding extents derived from the instance data. A concrete physical index can be created by selecting appropriate data structures to store the graph and the extents.

Structure indexing helps to find data items that satisfy structural constraints in queries by locating nodes in the structural summary graph that satisfy the query conditions (expecting far less summary nodes t ...

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