Structured indexes on results of function applications over data
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Abstract
Indexed views or materialized views are used as a secondary index on a base table with multi-valued attributes. This provides for using the index to search in the nested data. Moreover, indexing is provided on the result of an unnest operation. Indexing a view on the result of an unnesting operation provides the ability to index the contents of a nested collection. One such unnesting operation is “cross apply unnest”. This provides additional options for a query execution plan, leading to a more optimized query. A back-join is provided from the indexed view to the base table to allow fields from the base table that are not present in the indexed view to be included in a result of a query on the table which is processed using the indexed view as an access path. This provides a means of including columns in the query result that are not in the indexed view but are in the base table. The back-join is supported from a single-table indexed view to the base table via a unique clustering key which acts as a logical row locator. Thus, the system can back-join to the base table from an indexed view via the unique clustering key. These features allow the use of indexed views to index a table on the contents of multi-set or multi-valued attributes.
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Citations
20 Claims
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1-14. -14. (canceled)
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15. A computer-readable medium having stored thereon a data structure, comprising:
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a first data field containing an object; and
a second data field containing data associated with the object, the data being derived from a functional invocation over the data, the functional invocation comprising a table valued function. - View Dependent Claims (16, 17, 18, 19)
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20-33. -33. (canceled)
Specification