On optimizing an SQL-like nested query
ACM Transactions on Database Systems (TODS)
Retrospection on a database system
ACM Transactions on Database Systems (TODS)
The design and implementation of INGRES
ACM Transactions on Database Systems (TODS)
Access paths in the "Abe" statistical query facility
SIGMOD '82 Proceedings of the 1982 ACM SIGMOD international conference on Management of data
Query processing strategies in the PASCAL/R relational database management system
SIGMOD '82 Proceedings of the 1982 ACM SIGMOD international conference on Management of data
SIGMOD '84 Proceedings of the 1984 ACM SIGMOD international conference on Management of data
Extending the Algebraic Framework of Query Processing to Handle Outerjoins
VLDB '84 Proceedings of the 10th International Conference on Very Large Data Bases
Optimization of Nested Queries in a Distributed Relational Database
VLDB '84 Proceedings of the 10th International Conference on Very Large Data Bases
Benchmarking Database Systems A Systematic Approach
VLDB '83 Proceedings of the 9th International Conference on Very Large Data Bases
Exploiting uniqueness in query optimization
CASCON First Decade High Impact Papers
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Recent transformation algorithms for speeding up pro- cessing of nested SQL-like queries with aggregates are reviewed with respect to the correctness of aggregates over empty sets. It turns out that for a particular subset of such queries these algorithms fail to compute consistent answers. Unfortunately there seems to be no uniform way to do these transformations efficiently and correctly under all cir- cumstances. Also the algorithms for QUEL are reexamined regarding their correctness. It is shown that for a specific subset of QUEL-queries with aggregates a clearer semantics can be associated. Finally, benchmark results for lngres show that considerable performance advantages may be gained for such query types by using dynamic filters. The consequence of all these observations is that more research is required to integrate correlation queries with aggregates into a unified operator tree model.