The complexity of relational query languages (Extended Abstract)

Moshe Y. Vardi
1982 Proceedings of the fourteenth annual ACM symposium on Theory of computing - STOC '82  
Two complexity measures for query languages are proposed. Data complexity is the complexity of evaluating a query in the language as a function of the size of the database, and expression complexity is the complexity of ewduating a query in the language as a function of the size of the expression defining the query. We study the data and expression complexity of logical langnages -relational calculus and its extensions by transitive closure, fixpoint and second order existential quantification
more » ... and algebraic languages -relational algebra and its extensions by bounded and unbounded looping. The pattern which will bc shown is that the expression complexity of the investigated languages is one exponential higher then their data complexity, and for both types of complexity we show completeness in some complexity class.
doi:10.1145/800070.802186 dblp:conf/stoc/Vardi82 fatcat:4cdrq5vgajbf5ptlzg445345lu