Maintenance of Materialized Views with Outer-Joins
An materialized outer-join view is a materialized view whose defining expression contains at least one outer join. View maintenance refers to the process of bringing the view up to date after one or more of the underlying base tables has been updated. View maintenance can always be done by recomputing the result, known as a full refresh, but this is usually prohibitively expensive. Incremental view maintenance, that is, only applying the minimal changes required to bring the view up to date, is normally more efficient.
Full outer join (called generalized join) was proposed by Lacroix and Pirotte in 1976 . During the 1980s, there was considerable discussion in the research literature about the use and power of outer joins. Commercial systems began supporting outer joins in the late 1980s and at the time of writing (2007) all major commercial systems do. Optimization of outer-join queries was an active research area during the 1990s. Outer join was...
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