A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freelyreorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990. Home/Search Document Not in Database Summary Related Articles Check |
This paper is cited in the following contexts:
Outerjoins as Disjunctions - Galindo-Legaria (Correct)
....if sch(p) intersects the scheme of n base relations of the database. Note that our definition of predicate covers arbitrary, user defined predicates. We call a predicate p strong with respect to a set S of attributes if, whenever a tuple t has a null value for all attributes in S, p(t) False [RGL90]. Comparisons (and boolean combinations of comparisons) in the where clause of SQL queries actually behave as strong predicates, on each of the attributes they reference. If an attribute being compared turns out to be null for a given tuple, the value of the predicate is unknown, and the tuple ....
.... list of identities for joins, left outerjoins, and full outerjoins is given in [GLR93] An initial motivation for our join disjunctions was to facilitate the proof of identities with outerjoins, which is somewhat involved if we transform left into right hand side expressions algebraically see [RGL90, OMO89], for example. Our disjunctive normal form is in the worst case exponential on the number of relations of the query. This is to be expected, since it encodes operator trees of non associative operators. Still, we believe it is an intuitive formalism, appropriate for reasoning about outerjoin ....
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A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freely-reorderable outerjoins. In Proceedings of ACM-SIGMOD 1990 International Conference on Management of Data, Atlantic City, New Jersey, 1990.
Nested Queries in Object Bases - Cluet (31 citations) (Correct)
....While these algebraic operators are a nice solution to some of the above problems, they raise new issues. If a sequence of join operations can easily be reordered, joins and outer joins do not commute that easily and one has to find new ways of dealing with multi layered nested queries [8, 20, 22]. Finally, a unifying framework for different unnesting strategies was proposed in [21] There exist some significant differences between nested queries in the oo and the relational context. First, the result of an oo nested query is not always flat. Second, nested queries in the relational ....
....combination is the possibility of several interesting implementations for this combination where the straightforward nested loop evaluation is only one of them. Another good reason is the reordering possibilities it offers in case of a more complex query (i.e. more levels of nesting) [8, 20, 22, 21]. Hence, we apply the following equivalence which allows to unnest nested operations: g:f(oe A 1 =A 2 (e2 ) e 1 ) A2 (e 1 1 g=f( A1=A2 ( Gamma g;A2 ;f (e 2 ) if A i A(e i ) F(e 2 ) A(e 1 ) A 1 A 2 = g 62 A(e 1 ) A(e 2 ) The superscript g = f( is the default ....
A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freely-reorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990.
Extensible/Rule Based Query Rewrite Optimization in.. - Pirahesh, Hellerstein.. (1992) (19 citations) (Correct)
....= ENFORCE AND upper.body.distinct = PERMIT) fupper.body.distinct = ENFORCE;gg Table 2: Rule 1 SELMERGE to be defined for such queries as well, so even though these are not converted to a single SELECT, they are often subject to some useful transformation. For example, Rosenthal [RGL90] defines a set of such transformations for outer join. In this section we will describe the set of rules in Starburst which lead up to the merger of SELECT boxes. In Figure 2 we show the dependencies among the rules, particularly when the execution of one rule (at the tail of an arrow) can cause ....
Arnon Rosenthal and Cesar Galindo-Legaria. Query graphs, implementing trees, and freely-reorderable outerjoins. In Proc. SIGMOD 90 [Pro90].
Classification and Optimization of Nested Queries in Object.. - Cluet, Moerkotte (1994) (5 citations) (Correct)
....is even more powerful and is used to more elegantly unnest queries where an outerjoin followed by a unary grouping is needed. The binary grouping operator generalizes the nest join operator of [29] The optimization of relational nested queries has been studied thoroughly in the last decade [20, 19, 13, 10, 14, 24, 26, 25]. Naturally, our research has been influenced by this body of work. The classification of relational nested queries introduced in [20] proved to be useful for relational unnesting. Based on this observation, we extended this classification to the oo context. This extension is necessary due to the ....
A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freelyreorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990.
Nested Queries in Object Bases - Cluet, Moerkotte (31 citations) (Correct)
....unnesting of SQL queries at the SQL level [16] The main motivation was a demonstrated substantial gain in efficiency due to unnesting. In order to eliminate some bugs which where subsequently detected, outer joins were used [14, 7, 9, 17] Reordering of outer joins became an important topic [7, 17, 19]. Last, a unifying framework for different unnesting strategies was proposed in [18] There exist some significant differences between nested queries in the oo and the relational context. First, the result of an oo nested query is not always flat. Second, nested queries in the relational context ....
....combination is the possibility of several interesting implementations for this combination where the straightforward nested loop evaluation is only one of them. Another good reason is the reordering possibilities it offers in case of a more complex query (i.e. more levels of nesting) [7, 17, 19, 18]. Hence, we apply the following equivalence which allows to unnest nested operations: g:f(oe A 1 =A 2 (e 2 ) e 1 ) A 2 (e 1 1 g=f( A 1 =A2 ( Gamma g;A2 ;f (e 2 ) 1) if A i A(e i ) F(e 2 ) A(e 1 ) A 1 A 2 = g 62 A 1 [ A 2 The superscript g = f( is the default ....
A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freelyreorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990.
Extensible Query Processing in an Object-Oriented Database - Mitchell (1993) (19 citations) (Correct)
....the query. A difference in the solutions is that Project does a left outer join, so could result in vehicles related to empty sets of residences. In this example, the empty sets could easily be eliminated if necessary. There is a large body of research for dealing with outerjoin operations [38, 50, 120, 122]. The two query expressions differ significantly in their use of variables. In the first query, variable reference is nested, while in the second query all variables are local to the operation using them. The second query is similar to relational queries in which a Join of all relations aggregates ....
Arnon Rosenthal and C'esar Galindo-Legaria. Query Graphs, Implementing Trees, and FreelyReorderable Outerjoins. In SIGMOD Proceedings, pages 291--299. ACM, 1990.
Nested Queries in Object Bases - Cluet, Moerkotte (1995) (31 citations) (Correct)
No context found.
A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freelyreorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990.
Three Cases for Query Decorrelation in XQuery - May, Helmer, Moerkotte (2003) (Correct)
No context found.
A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freely-reorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990.
Nested Queries and Quantifiers in an Ordered Context - May, al. (2003) (1 citation) (Correct)
No context found.
A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freely-reorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990.
Three Cases for Query Decorrelation in XQuery - May, Helmer, Moerkotte (2003) (Correct)
No context found.
A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freely-reorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990.
Nested Queries and Quantifiers in an Ordered Context - May, Helmer, Moerkotte (2003) (Correct)
No context found.
A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freely-reorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990.
Nested Queries in Object Bases - Cluet, Moerkotte (1995) (31 citations) (Correct)
No context found.
A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freelyreorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990.
Nested Queries and Quantifiers in an Ordered Context - May, Helmer, Moerkotte (2004) (Correct)
No context found.
A. Rosenthal and C. Galindo-Legaria. Query graphs, implementing trees, and freely-reorderable outerjoins. In Proc. of the ACM SIGMOD Conf. on Management of Data, pages 291--299, 1990.
Data Integration Using Self-Maintainable Views - Gupta, Jagadish, Mumick (1996) (25 citations) (Correct)
No context found.
Arnon Rosenthal and Cesar Galindo-Legaria. Query Graphs, Implementing Trees, and FreelyReorderable Outerjoins.
An Object Based Algebra for Parallel Query Processing and.. - Sarathy, Saxton (1992) (Correct)
No context found.
A. Rosenthal and C.G. Legaria. Query Graphs, Implementing Trees, and Freely-Reorderable Outerjoins. In Proc. ACM SIGMOD Int'l Conf. on Management of Data, Atlantic City, New Jersey, 1990, pp. 291--299.
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