2002/10/29 by Sara Cohen, Cohen, Sara, Werner Nutt +3
Computer Science · #Advanced Database Systems and Queries #Data Management and Algorithms #Databases (cs.DB) #F.4.1 #FOS: Computer and information sciences #H.2.3 #H.2.4 #Logic in Computer Science (cs.LO) #Logic, Reasoning, and Knowledge #cs.DB #cs.LO
paper · pdf · doi:10.48550/arxiv.cs/0210028
28 pages
openalex publication_date 2002/10/29 · arxiv created 2002/10/30 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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, toptwo 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 count distinct and average. For quasilinear queries (i.e., queries where 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, parity, prod, toptwo and average. A similar result holds for count distinct provided that a few additional conditions hold. The results are couched in terms of abstract characteristics of aggregation functions, and new proof techniques are used. Finally, the results above also imply that equivalence, under bag-set semantics, is decidable for non-aggregate queries with negation.