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VLDB
1987
ACM

Magic Functions: A Technique to Optimize Extended Datalog Recursive Programs

8 years 9 months ago
Magic Functions: A Technique to Optimize Extended Datalog Recursive Programs
Severalmethodshavebeenproposedto compile recursive Datalog programs. The most well-known perform a rewriting of rules using MAGIC or PROBLEM predicates in order to push selectionsbeforerecursion.Rewritten rule systemsaregenerally complex anddifficult to translateinto optimized relational algebraprograms.Moreover,theyoften generatetoo many results; thus, the query must be applied to the generatedresults to eliminate non relevant answers. In this paper, after a survey of the existing compilation techniqueswhich points out their limitations, we develop the magic function method iutroduced in [GardariuDeMaindreville86]. It is basedon an understandingof the query as a function which mapscolumns of a relation to other columns. A query against recursive rules is then translated into a fixpoint functional equation. The resolution of this fixpoint equation using Tarski's theorem leads to efficient computation of the query answer. In particular, the derived algorithms push selections throu...
Georges Gardarin
Added 28 Aug 2010
Updated 28 Aug 2010
Type Conference
Year 1987
Where VLDB
Authors Georges Gardarin
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