Incremental maintenance of materialized views containing one-to-

Details Incremental maintenance of materialized views containing one-to- Incremental maintenance of materialized views containing one-to-

1998-07-02

2000-10-17

Alam, Hosain T.

Data processing: database and file management or data structures

Database design

Data structure types

707 2, 707 4, 707 6, G06F 1730

Patent

active

061345431

ABSTRACT:
A method and apparatus are provided for performing incremental refreshes to materialized views defined by one-to-one lossless joins. Each base table of the materialized view is selected to be processed as the current "selected table". During the processing, if the selected table is the right table of an outer join, then selected columns of rows of the materialized view are set to NULL based on rows of the selected table that have been updated or deleted in the selected table after a prior refresh operation. Then, NULL values in selected columns of the materialized view are updated to reflect new values caused by updates and inserts into the selected table that occurred after the prior refresh operation. If the selected table is not the right table of an outer join, then rows from the materialized view are deleted based on rows of the selected table that have been updated or deleted in the selected table after the prior refresh operation. Then, rows are inserted into the materialized view based on updates and inserts into the selected table that occurred after the prior refresh operation. The incremental refresh techniques are "memoryless" in that they do not require a record of the sequence of changes that were made subsequent to the prior refresh operation. Techniques are described for performing the incremental refresh steps through the use of database commands and queries.

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