Safety, domain independence and translation of complex value database queries

Liu, Hong-Cheu; Yu, Jeffrey Xu; Liang, Weifa

doi:10.1016/j.ins.2008.02.005

Cited by 5 publications

(3 citation statements)

References 27 publications

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“…In [12], Liu and Yu have proved that every em-allowed formula in CALC cv is e f -domain independent and embedded domain independent. If all external functions are computable, it is easy to get the following result.…”

Section: Safe Queriesmentioning

confidence: 99%

“…For stratified Datalog cv queries, em-allowed does not imply embedded domain independence [12]. Em-allowed does not imply finiteness as the query fp0 ; pn pm^succm = ng is em-allowed but not finite.…”

Section: Em-allowed Finiteness and Domain Independencementioning

confidence: 99%

“…Some attempts to extend the theory of (complex value) database queries to augment with arithmetic operators and external functions have already been made [8,17,19,12]. None of these attempts, however, address all the aspects mentioned above.…”

Section: Introductionmentioning

confidence: 99%

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Safe database queries with external functions

Liu

Yu²

Proceedings. IDEAS'99. International Database Engineering and Applications Symposium (Cat. No.PR00265)

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We consider the theory of database queries with functions on the complex value data model. The notion of a syntactic criteria, called "embedded allowed", for queries which guarantee embedded domain independence, is generalized for this model. We show that all embedded allowed calculus (or fix-point) queries are external function-domain independent and continuous. We also develop an algorithm for translating embedded allowed queries into equivalent algebraic expressions as a basis for evaluating safe queries in all calculus-based query classes.In the second part of this paper, we compare the expressive power of various complex value query languages extended with functions and their certain restricted versions. If we assume polynomial time (space) complexity of external functions and type usage by the database, such as density, then strongly embedded allowed inflationary (partial) fix-point queries express precisely QPT IME (QPSPACE). Finally, we show the relationship between properties such as embedded domain independence, finiteness and embedded allowed in various calculus-based query languages.

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Section: Safe Queriesmentioning

confidence: 99%

Section: Em-allowed Finiteness and Domain Independencementioning

confidence: 99%