TY - CHAP
T1 - Containment of aggregate queries
AU - Cohen, Sara
AU - Nutt, Werner
AU - Sagiv, Yehoshua
PY - 2003
Y1 - 2003
N2 - The problem of deciding containment of aggregate queries is investigated. Containment is reduced to equivalence for queries with expandable aggregation functions. Many common aggregation functions, such as max, cntd (count distinct), count, sum, avg, median and stdev (standard deviation) are shown to be expandable. It is shown that even in the presence of integrity constraints, containment can be reduced to equivalence. For conjunctive count and sum-queries, simpler characterizations for containment are given, that do not require checking equivalence. These results are built upon in order to solve the problem of finding maximally-contained sets of rewritings for conjunctive count-queries. © Springer-Verlag Berlin Heidelberg 2003.
AB - The problem of deciding containment of aggregate queries is investigated. Containment is reduced to equivalence for queries with expandable aggregation functions. Many common aggregation functions, such as max, cntd (count distinct), count, sum, avg, median and stdev (standard deviation) are shown to be expandable. It is shown that even in the presence of integrity constraints, containment can be reduced to equivalence. For conjunctive count and sum-queries, simpler characterizations for containment are given, that do not require checking equivalence. These results are built upon in order to solve the problem of finding maximally-contained sets of rewritings for conjunctive count-queries. © Springer-Verlag Berlin Heidelberg 2003.
UR - http://www.scopus.com/inward/record.url?scp=35248861537&partnerID=8YFLogxK
U2 - 10.1007/3-540-36285-1_8
DO - 10.1007/3-540-36285-1_8
M3 - Chapter (peer-reviewed)
SN - 978-3-540-00323-6
VL - 2572
T3 - Lecture Notes in Computer Science
SP - 111
EP - 125
BT - Database Theory — ICDT 2003
T2 - 9th International Conference on Database Theory
Y2 - 8 January 2003 through 10 January 2003
ER -