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SQL Anywhere 11.0.1 (Français) » SQL Anywhere Server - SQL Usage » Query Processing » Query optimization and execution » Query execution algorithms » Types of algorithms » Query expression algorithms


UnionAll algorithm (UA)

UnionAll reads rows from each of its inputs and outputs them, regardless of duplicates. This algorithm is used to implement UNION and UNION ALL clauses. In the UNION case, a duplicate elimination algorithm such as HashDistinct or OrderedDistinct is needed to remove any duplicates generated by UnionAll.

See HashDistinct algorithm (DistH), and OrderedDistinct algorithm (DistO).