Conjunctive queries with comparisons

  • What are unions of conjunctive queries?

    The class UCQ (Union of Conjunctive Queries) is obtained by adding union to conjunctive queries.
    A UCQ is a query of the form q1 ∪ q2 ∪ qm, where each qi is a conjunctive query..

  • What is conjunctive queries with negation?

    A conjunctive query with negation (CQ\xac) is of the form: q = ans(x1 xq) ← p1,,pn,n1,,nm, where each pi (resp. ni ) is a positive (resp. negative) subgoal, 1 ≤ n + m, and ans is a special relation (which defines the answer part of the query)..

  • In database theory, a conjunctive query is a restricted form of first-order queries using the logical conjunction operator.
    Many first-order queries can be written as conjunctive queries.
    In particular, a large part of queries issued on relational databases can be expressed in this way.
  • The class UCQ (Union of Conjunctive Queries) is obtained by adding union to conjunctive queries.
    A UCQ is a query of the form q1 ∪ q2 ∪ qm, where each qi is a conjunctive query.
Conjunctive queries with predicates in the form of comparisons that span multiple relations have regained interest recently, due to their relevance in OLAP queries, spatiotemporal databases, and machine learning over relational data. The standard technique, predicate pushdown, has limited efficacy on such comparisons.
Conjunctive queries with predicates in the form of comparisons that span multiple relations have regained interest recently, due to their relevance in OLAP queries, spatiotemporal databases, and machine learning over relational data. The standard technique, predicate pushdown, has limited efficacy on such comparisons.

Can aggregation queries with comparisons be applied?

Theoretically, it is an intriguing question if our techniques can be applied to aggregation queries with comparisons.
Currently, such queries can only have short comparisons ; long comparisons can only be dealt with using GHDs, leading to super- linear time.
In practice, cost-based optimization can be added to our Query optimization.

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Can linear time be achieved for acyclic conjunctive queries?

A 40-year-old result by Yannakakis tells us that linear time can be achieved for - acyclic conjunctive queries (CQs), and recent negative results [3, 20] suggest that this is also probably the best one can hope for. 1The ̃ notation suppresses a log (1) factor.

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What is a conjunctive query?

Conjunctive Queries with Comparisons Conjunctive queries with predicates in the form of comparisons that span multiple relations have regained interest recently, due to their relevance in OLAP queries, spatiotemporal databases, and machine learning over relational data.

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What is the difference between naive and free connex CQC?

′ is now a free-connex CQC, so our algorithm can compute it in time ̃ ( + | ′( )|), whereas using naive algorithm has running time of ̃ ( + | ∗( )|), ∗ where is the full query of , where all attributes are output attributes.
They are both larger than the true output size OUT = .

In database theory, a conjunctive query is a restricted form of first-order queries using the logical conjunction operator.
Many first-order queries can be written as conjunctive queries.
In particular, a large part of queries issued on relational databases can be expressed in this way.
Conjunctive queries also have a number of desirable theoretical properties that larger classes of queries do not share.

Categories

Conjunctive queries examples
Conjunctive queries with negation
Conjunctive queries relational databases
Conjunctive queries tutorial
Conjunctive queries problems
Conjunctive queries inclusion dependencies
Graphical conjunctive queries
Inference conjunctive queries
Join conjunctive queries
Union of conjunctive queries
Equivalence of conjunctive queries
Evaluation of conjunctive queries
Theory of conjunctive queries
Conjunctive queries equality
Conjunctive query answering
Conjunctive query algorithm
Conjunctive conjunction examples
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