Additionally, four more problems related to enumeration are also considered in the thesis. Intuitively, this means that there is a two-phase algorithm working as follows: a preprocessing phase that works in time linear in the size of the database, followed by an enumeration phase outputting one by one all the elements of q(D) with a constant delay (which is independent from the size of the database) between any two consecutive outputs. The main focus of this thesis is a particular solution to this problem: a scenario where in stead of just computing, we are interested in enumerating q(D) with constant delay. It can therefore require too many of the available resources to compute it entirely. However, the set q(D) may be larger than the database itself as it can have a size of the form n^l where n is the size of the database and l the arity of the query. Given a query q and a database D it is to compute the set q(D) of all tuples in the output of q on D. This thesis is concentrated around the problem of query evaluation.
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