Index tuning as part of database tuning is the task of selecting and creating indexes with the goal of reducing query processing times. However, in dynamic environments with various ad-hoc queries it is difficult to identify potentially useful indexes in advance. In this paper, we investigate an approach addressing this problem by deciding about index creation automatically at runtime in order ...

aim: this study investigates the intraspecific competition, for food and density amongst larvae of anopheles stephensi (main malaria vector in south iran). material & methods: the effects of 4 selected food quantities (1x,2x,4x,6x) and 5 larval densities (0.1 to 3 larva/cm2) were tested individually or in combination on 7 biological indexes of the vector and the results were statistically ...

Most extensible database systems support addition of new indexes or new data types. However, the reference patterns exhibited by these new indexes may not be efficiently supported by existing buffer replacement strategies. In this paper, we propose a new mechanism that allows an index method to pass replacement hints to the buffer manager by assigning priority values to the buffer pages to refl...

We introduce the first grammar-compressed representation of a sequence that supports searches in time that depends only logarithmically on the size of the grammar. Given a text T [1..u] that is represented by a (context-free) grammar of n (terminal and nonterminal) symbols and size N (measured as the sum of the lengths of the right hands of the rules), a basic grammar-based representation of T ...

We study parallel and distributed compressed indexes. Compressed indexes are a new and functional way to index text strings. They exploit the compressibility of the text, so that their size is a function of the compressed text size. Moreover, they support a considerable amount of functions, more than many classical indexes. We make use of this extended functionality to obtain, in a shared-memor...

In this paper we extend the work of Färe and Zelenyuk (2003) to find a theoretically justified method of aggregating Malmquist Productivity Indexes over individual decision making units (firms, countries, etc.) into a group Malmquist Productivity Index. We also consider the aggregation of decomposed parts of the Malmquist Productivity Index to obtain a decomposition of the Malmquist Productivit...

In [SPAA2007], Bender et al. define a streaming B-tree (or index) as one that supports updates in amortized o(1) IOs, and present a structure achieving amortized O((logN)/B) IOs and queries in O(logN) IOs. We extend their result to the partially-persistent case. For a version v, let Nv be the number of keys accessible at v and N be the total number of updates. We give a data structure using spa...

We present a new structural characterization of the expressive power of the acyclic conjunctive queries in terms of guarded simulations, and give a finite preservation theorem for the guarded simulation invariant fragment of first order logic. We discuss the relevance of these results as a formal basis for constructing so-called guarded structural indexes. Structural indexes were first proposed...

The lymphocytes of asymptomatic, seropositive donors demonstrated blastogenic responses to early antigens of human cytomegalovirus whether or not antibodies to early antigens were detectable. The lymphocytes of six of nine patients with active cytomegalovirus infections gave stimulation indexes of greater than or equal to 2.00 with antigens of productively infected cells, whereas only two patie...

Multifractal analysis and extensive statistical tests are performed upon intraday minutely data within individual trading days for four stock market indexes (including HSI, SZSC, S&P500, and NASDAQ) to check whether the indexes (instead of the returns) possess multifractality. We find that the mass exponent τ(q) is linear and the singularity α(q) is close to 1 for all trading days and all index...