S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. Foundations of DD and LP 1988.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....be simplified to find the title and author of books . The minimization we just performed is constraint dependent minimization (CDM) as it depends on the knowledge of ICs that hold for a database. Query minimization under ICs is traditionally achieved using semantic query optimization techniques [5]. Existing techniques for semantic query optimization base themselves on the notion of a residue using which one rewrites a query into an equivalent query. While semantic query optimization can add or delete a subgoal (node and edge for us) for tree pattern minimization only deletion is relevant. ....

....grouping and aggregates is NP complete. Millstein et al. 21] study the problem of containment relative to available data sources in the context of data integration and show that it is decidable. Semantic query optimization has a long history and we only mention a few papers. Chakravarthy et al. [5] proposed a technique based on the notion of a residue of an IC against a query for optimizing non recursive relational queries. Calvanese et al. 4] consider the problem of conjunctive query containment in an abstract setting that covers relational and OO models, under a class of special ....

S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. Foundations of DD and LP 1988.

....be simplified to find the title and author of books . The minimization we just performed is constraint dependent minimization (CDM) as it depends on the knowledge of ICs that hold for a database. Query minimization under ICs is traditionally achieved using semantic query optimization techniques [2]. Existing techniques for semantic query optimization base themselves on the notion of a residue using which one rewrites a query into an equivalent query. While semantic query optimization can add or delete a subgoal (node and edge for us) for tree pattern minimization only deletion is relevant. ....

....grouping and aggregates is NP complete. Millstein et al. 15] study the problem of containment relative to available data sources in the context of data integration and show that it is decidable. Semantic query optimization has a long history and we only mention a few papers. Chakravarthy et al. [2] proposed a technique based on the notion of a residue of an IC against a query for optimizing non recursive relational queries, Calvanese et al. 1] consider the problem of conjunctive query containment in an abstract setting that covers relational and OO models, under a class of special ....

S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. Foundations of DD and LP 1988.

....make use of association rules to add or remove constraints, or to find contradictions or tautologies. In this dissertation we focus on the application of the first and third conditions, although the algorithms proposed can be adapted to serve all of the heuristics. Chakravarthy et al. CGM90, CGM88] also study the use of semantic knowledge for the transformation of queries into more efficient forms. They use a set of heuristics similar to those described above and propose techniques that take advantage of integrity constraints in the form of rules. Bell [Bel96] has studied the use of ....

U.S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In Foundations of Deductive Databases and Logic Programming (DDLP), pages 243--273, 1988.

....exponential upper bound is provided for containment of COQL queries. In [Bid87] it is shown that containment of conjunctive queries for the Verso complex value model and algebra is reducible to the relational case. Other studies include semantic query optimization for unions of conjunctive queries [CGM88], containment under Datalog expressible constraints and views [DS96] and containment of non recursive Datalog queries with regular expression atoms under a rich class of constraints [CGL98] We are not aware of any extension of the chase to complex values and oodb models. Hara and Davidson [HD98] ....

U.S. Chakravarthi, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Foundations of Deductive Databases and Logic Programming, pages 243--273, San Mateo, California, 1988. Morgan-Kaufmann.

....upper bound is provided for containment of COQL queries. In [Bid87] it is shown that containment of conjunctive queries for the Verso complex value model and algebra is reducible to the relational case. Other studies include semantic query optimization for unions of conjunctive queries [CGM88] containment under Datalog expressible constraints and views [DS96] and containment of non recursive Datalog queries with regular expression atoms under a rich class of constraints [CGL98] We are not aware of any extension of the chase to complex values and oodb models. Hara and Davidson ....

U.S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Foundations of Deductive Databases and Logic Programming, pages 243--273, San Mateo, California, 1988. Morgan-Kaufmann.

....and aside from identifying the class that is missing information, there is no capability to explain exactly what portion of the query is responsible for the incompleteness. There has been work on the notion of residues in the context of Semantic Query Optimization in deductive databases [3]. A residue is the interaction of an integrity constraint and an intensional axiom. Such residues are used to speed up query processing. 4.1 Future Applications and Research Presuming that a common knowledge ontology may be converted to a universal relation, and assuming that resource agent ....

U. S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Proc. Workshop on Foundations of Deductive Databases and Logic Programming, pages 67--101, Washington, D.C., August 18-22, 1986.

....be simplified to find the title and author of books . The minimization we just performed is constraint dependent minimization (CDM) as it depends on the knowledge of ICs that hold for a database. Query minimization under ICs is traditionally achieved using semantic query optimization techniques [2]. Existing techniques for semantic query optimization base themselves on the notion of a residue using which one rewrites a query into an equivalent query. While semantic query optimization can add or delete a subgoal (node and edge for us) for tree pattern minimization only deletion is relevant. ....

....grouping and aggregates is NP complete. Millstein et al. 15] study the problem of containment relative to available data sources in the context of data integration and show that it is decidable. Semantic query optimization has a long history and we only mention a few papers. Chakravarthy et al. [2] proposed a technique based on the notion of a residue of an IC against a query for optimizing non recursive relational queries, Calvanese et al. 1] consider the problem of conjunctive query containment in an abstract setting that covers relational and OO models, under a class of special ....

S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. Foundations of DD and LP 1988.

.... as is already done in logic programming [9, 30] CFDs can be used in detecting query emptiness independent of the underlying database [13] which has applications to transaction scheduling and recomputation of materialized views [14] There are also applications to semantic query optimization [8], design of database schemas, and knowledge discovery [41] The original use of finiteness dependencies was in determining the safety of queries [33] that is, determining that queries involving infinite relations nevertheless produce a finite answer. Finiteness dependencies are used in [22] to ....

....On the other hand, it results in simpler updates of the relation than the method of [10] since there is no necessity to transfer a tuple from one subrelation to another when another tuple is added or deleted from the relation. ffl We can use CFDs and CGDs to perform semantic query optimization [8] on queries to relational or other databases. A simple example is the query c; p( x; y) p( x; z) when p satisfies the CFD c 0 ) x y. This query can be simplified to c; y = z; p( x; y) provided D j= c c 0 . ffl Elkan [13, 14] uses FDs to detect query emptiness ....

U.S. Chakravarthy, J. Grant and J. Minker, Foundations of Semantic Query Optimization for Deductive Databases, in: Foundations of Deductive Databases and Logic Programming, J. Minker (Ed), Morgan Kaufmann, 243--274, 1988.

....optimization is concerned, the situation to date is similar to the situation of intensional answer generation: there are a number of initial studies in various formal systems, but no convincing, generally acknowledged solution has emerged yet. As introductory literature we recommend [SO87] and [CGM88]. 10 3 Recursive Rule Handling Many traditional database researchers still regard recursion as not much more than a curiosity. If considering the matter a little bit more seriously and without prejudices, however, one will soon understand that recursive rules are by no means just exotic ....

U. Chakravarthy, J. Grant, and J. Minker, "Foundations of semantic query optimization for deductive databases", in: [Min88a]

....as those studied in [6, 17, 19] However, by the results established in this paper, path constraint implication will be undecidable in the context of these more general type systems. Constraints in object oriented databases a retrospective. While there has been considerable recent activity [12, 13, 16, 22] in optimizing object oriented queries in the presence of constraints, there has, to our knowledge, been almost no work on the formulation of constraints, let al..one the study of the implication problem. In [22] a rather general approach is taken: constraints are represented as queries that are ....

U. S. Chakravarthy, J. Grant, and J. Minker. "Foundations of semantic query optimization for deductive databases". In J. Minker, editor, Foundations of Deductive Databases and Logic Programming . Morgan Kaufmann, San Mateo, California, 1988.

....and aside from identifying the class that is missing information, there is no capability to explain exactly what portion of the query is responsible for the incompleteness. There has been work on the notion of residues in the context of Semantic Query Optimization in deductive databases [3]. A residue is the interaction of an integrity constraint and an intensional axiom. Such residues are used to speed up query processing. 4.1 Future Applications and Research Presuming that a common knowledge ontology may be converted to a universal relation, and assuming that resource agent ....

U. S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Proc. Workshop on Foundations of Deductive Databases and Logic Programming, pages 67--101, Washington, D.C., August 18-22, 1986.

....multiple applications of the model generation procedure to subsets of the required (ground) answer. Testing for answer minimality when the minimal model state is used is part of the query evaluation process and comes at no additional cost. The approaches for efficient query evaluation discussed in [26, 4] can be applied as pre processing step in our approach. The use of a similar approach to answering queries under different database semantics such as stable and perfect semantics and the development of an integrated system based on using minimal model generators for different aspects of database ....

U.S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Proc. Workshop on Foundations of Deductive Databases and Logic Programming, pages 67--101, Washington, D.C., August 1986.

....age : A) ward (patient : P, ward name : W) Q 5 ) infected (patient : P, infection : I) disease (name : I, type : T) contagious (name : I, vector : V, rate : R) A 33, R high, W = maternity, T = staphylococcus, V = air. This canonical form of a Datalog query is called variable substituted [4]. 15 We shall assume for the purposes of false presuppositions (finding the MFSs) that queries are in variable substituted form. Thus we consider a query s length to be the number of tables (and views) it involves plus the number of selects in the query. Assuming an equivalent relational schema, ....

U. S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Proc. Workshop on Foundations of Deductive Databases and Logic Programming, pages 67--101, Washington, D.C., Aug. 1986.

....optimization techniques were first proposed in the context of re29 lational databases [Kin81, HZ80, Jar84] and dealt with rather simple types of constraints stating e.g. referential integrity and functional dependencies. For deductive databases and general integrity constraints in clausal form, CGM88, CGM90, GL92, Kow92] describe a rewriting of queries and rules. This technique has also been used for generating cooperative answers [Gaa92] Several papers [SO89, HLO91] deal with the implementation of semantic query optimizers, especially schemes for deciding which rules and integrity ....

U.S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Foundations of deductive databases and Logic programming, pages 243--273. Morgan Kaufmann, 1988.

....Most of the current works focuses on query optimization [19, 4, 9] in relational and deductive databases, due to a clear query model in these contexts [18, 15] Several approaches to optimization have been proposed. It is possible to make ad hoc optimization [9] consider semantic constraints [6, 10] or implementation issues [17] These approaches to optimization are not alternative but integrative. For instance, ad hoc optimization based on special physical data structures can be done altogether with optimization based on semantic constraints. They work at different levels (i.e. physical ....

U. S. Chakravarthy, J. Grant, and J. Minker. Foundations of Semantic Query Optimization for Deductive Databases. In J. Minker, editor, Foundations of Deductive Databases and Logic Programming, pages 243--273. Morgan Kaufmann, 1988.

....work to combine both approaches. Our framework also takes advantage of the available constraints in order to reduce the size of Needed(T; E) and increase the effectiveness of expiration. This is different from, but related to, the use of constraints in the area of semantic query optimization [CGM88]. It is important to point out their connection since semantic query optimization has largely been ignored in view maintenance literature. Indeed, there has been some prior work in improving view maintenance using constraints; however, they all use special case algorithms to take advantage of ....

U. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In Foundations of Deductive Databases and Logic Programming, pages 243-- 273. Morgan Kaufman, 1988.

....and aside from identifying the class that is missing information, there is no capability to explain exactly what portion of the query is responsible for the incompleteness. There has been work on the notion of residues in the context of Semantic Query Optimization in deductive databases [3]. A residue is the interaction of an integrity constraint and an intensional axiom. Such residues are used to speed up query processing. 4.1 Future Applications and Research Presuming that a common knowledge ontology may be converted to a universal relation, and assuming that resource agent ....

U. S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Proc. Workshop on Foundations of Deductive Databases and Logic Programming, pages 67--101, Washington, D.C., August 18-22, 1986.

....be satisfied by the database. GCI and TH must satisfy the condition GCI TH should be consistent. TH is a finite set of axioms which comprises IDB and EDB . For a database to be in a valid state, all of the GCIs are satisfied. Therefore, a query Q can be viewed as Q GCI 1 GCI n [2]. Although theoretically sound, running a theorem prover on the query and entire set of GCIs is not practical. The database system does not need all GCIs to answer queries. Now consider a sample database from [3] For simplicity, we omit age property without loss of generality. Moreover we do not ....

U. S. Chakravarthy, J. Grant and J. Minker. Foundations of Semantic Query Optimization for Deductive Databases. In J. Minker, ed., Foundations of Deductive Databases and Logic Programming, pages 243-273. Morgan Kaufmann, 1987.

.... query (see section 8 below) Another direction is semantic optimisation, which seeks to transform a query into another query which has the same set of answers but which is cheaper to evaluate [HZ80] Semantic optimisation is often applied to databases which support integrity constraints [Kin81, CGM88] theorem proving techniques are used to transform the query into a simpler query that, under the given integrity constraints, is logically equivalent. By contrast, magic checking does not require information about the semantics of the database. It is not an optimisation based on semantics at ....

U. S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Foundations of Deductive Databases and Logic Programming, pages 243--273. Morgan Kaufmann, 1988.

....query optimization is especially important in applications that require integrating multiple heterogeneous Work supported in part by BSF grant 92 00360. sources of data (e.g. CGMH 94, LSK95] The topic of semantic query optimization has been investigated in many papers (e.g. Kin81, CGM88] and is well understood for queries that can be represented as a union of conjunctive queries. For queries involving recursion, or which cannot otherwise be translated to a union of conjunctive queries (because of aggregation or duplicates) semantic query optimization has largely remained an ....

....subgoals) Since ic s are a special case of conjunctive queries, the containment algorithm of [CV92] can be used to determine satisfiability of recursive rules in the presence of ic s. Obviously, determining satisfiability of a set of rules is an important part of semantic query optimization. In [CGM88] Chakravarthy et al. have shown that the core of semantic query optimization is computing residues. Intuitively, a residue is some part of an integrity constraint that cannot be mapped into the body of a rule, and therefore, its negation can be added to the rule. In particular, if the residue is ....

U. S. Chakravarthy, John Grant, and Jack Minker. Foundations of semantic query optimization for deductive databases. In Jack Minker, editor, Foundations of Deductive Databases and Logic Programming, pages 243-- 273. Morgan Kaufmann, Los Altos, CA, 1988.

....which has a bearing on the design of an optimizer for the deductive and active rules. For processing queries in nonrecursive deductive databases, conventional query optimization need only be augmented with a compilation phase to transform intensional relations in terms of extensional relations [CGM88, CGM90] The input query is first modified using the compiled (intensional) database, and then optimized using conventional query optimization techniques. As 3 for recursive query processing in deductive database, numerous strategies have been proposed [BR86, LV89, Sto90, WF90] In general,a ....

S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Foundations of Deductive Databases and Logic Programming, pages 243--273. Morgan Kaufmann Publications, 1988.

....optimization (SQO) techniques to query processing in object databases. SQO uses semantic knowledge in the form of integrity constraints (ICs) to reformulate an object query into an equivalent form that can be evaluated more efficiently. SQO has been applied to relational and deductive databases [4, 6, 5]. In particular, it was shown that a logic based approach using the method of partial subsumption is a general technique that encompasses various special cases of SQO considered by other researchers. Here, we demonstrate that SQO can be adapted to object databases. Our approach to SQO for object ....

....not only for maintaining the integrity of an object database during updates, but also in the increasing capability of a system to perform query optimization. The paper is organized as follows. The next section provides background on research in SQO. Section 3 reviews the residue technique of [4, 6, 5] which is used later in our optimization method. Section 4 is the central part of the paper; we present the ODMG data model, provide algorithms for schema and query transformation and show on several examples how our technique works. In Section 5 we suggest how queries with methods can be ....

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U. S. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimizations for deductive databases. In J. Minker, editor, Foundations of Deductive Databases and Logic Programming. Morgan-Kaufman, 1988.

....needs can be modeled as a set of constraints. UCs reflect the semantics that a particular user imposes on the DB and need not be consistent with the DB. UCs are used to modify a user s query so that the search space is limited, finding only answers that comply with the UCs. Semantic compilation [1] is used to incorporate ICs into a query and also applies to UCs. Consider the query Which airline can I travel on from Washington DC to Paris CDG airport : Q: travel(Airline,Airport,CDG,Time) near(Airport,Washington) and the UC I refuse to travel through JFK : UC: flight(Airline,No,L ....

U. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Foundations of Deductive Databases and Logic Programming, pages 243--274. Morgan-Kaufmann, 1987.

....and need not be consistent with the database. When answering queries posed by a user, they are used to modify a user s query so that the search space of the original query is limited to find only answers that are amenable to the user s needs. The semantic compilation method of Chakravarthy et al. [3] which Gal and Minker use to incorporate integrity constraints into a query can also be applied to user constraints. Consider a query to a database Which airline can I use to travel from Washington DC to Paris Charles de Gaulle airport : Q: travel(Airline,Airport,CDG,Time) ....

U. Chakravarthy, J. Grant, and J. Minker. Foundations of semantic query optimization for deductive databases. In J. Minker, editor, Foundations of Deductive Databases and Logic Programming, pages 243--274. Morgan-Kaufmann, 1987.

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U.S. Chakravarthy, J. Grant, and J. Minker, "Foundations of semantic query optimization for deductive databases," in J. Minker, Ed. Foundations of Deductive Databases and Logic Programming, San Francisco, CA: Morgan Kaufmann, 1988, pp. 243-274.

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