Equivalences among aggregate queries with negation

S. Cohen*, W. Nutt, Y. Sagiv

*Corresponding author for this work

Research output: Contribution to conferencePaperpeer-review

5 Scopus citations

Abstract

Query equivalence is investigated for disjunctive aggregate queries with negated subgoals, constants and comparisons. A full characterization of equivalence is given for the aggregation functions count, max, sum, prod, top2 and parity. A related problem is that of determining, for a given natural number N, whether two given queries are equivalent over all databases with at most N constants. We call this problem bounded equivalence. A complete characterization of decidability of bounded equivalence is given. In particular, it is shown that this problem is decidable for all the above aggregation functions as well as for cntd (count distinct), stdev (standard deviation), median and avg. For quasilinear queries (i.e., queries in which predicates that occur positively are not repeated) it is shown that equivalence can be decided in polynomial time for the aggregation functions count, max, sum, prod, top2, parity, and avg. A similar result holds for cntd provided that a few additional conditions hold. The resu lts are couched in terms of abstract characteristics of aggregation functions, and new proof techniques are used. Finally, the results presented also imply that equivalence, under bag-set semantics, is decidable for nonaggregate queries with negation.

Original languageAmerican English
Pages215-226
Number of pages12
DOIs
StatePublished - 2001
Event20th ACM SIGMOD-SIGACT-SIGART Symposium on Principles of Database Systems - Santa Barbara, CA, United States
Duration: 21 May 200123 May 2001

Conference

Conference20th ACM SIGMOD-SIGACT-SIGART Symposium on Principles of Database Systems
Country/TerritoryUnited States
CitySanta Barbara, CA
Period21/05/0123/05/01

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