The needs of new modern day applications such as network monitoring systems, telecommunications data management, web applications, remote medical monitoring applications and others for near real time results over continuous data streams have spurred the development of new data management systems called Data Stream Management Systems (DSMS). Unlike traditional database systems which answer one-time user queries only after the finite data has been captured on disk, DSMSs provide on-the-fly answers to user queries as data is arriving at various rates in the form of continuous, potentially infinite streams of tuples. To meet the timeliness requirements of applications, DSMSs aim to keep all data in main memory. Thus queries with multiple stateful operators pose a major strain on memory. Existing adaptation techniques designed to address this issue are ineffective when faced with continuous bursts of high data rates. When system load exceeds system capacity, a DSMS has three options: 1) discard some new data; 2) crash; or 3) spill data to disk. Only option three allows it to produce delayed, yet accurate and complete query results. However, this option involves disk access overhead and change in the natural order of tuples flowing through the query plan tree. As not all stream operators can process correctly out of order tuples, data spilling may have a negative impact on the quality of the final results. Moreover, since operators in a query plan are interconnected, changes in the order of tuple flows inevitably impact the stages of execution of affected downstream operators such as for example data purging . Data purging is necessary for processing continuous queries composed of stateful operators. The state of such operators is divided into finite non-overlapping sets of tuples called windows. Thus, after all the tuples for a window have been processed and all results output, these tuples can be discarded to free memory for new data. To address these issues, we have redesigned the state structure of continuous operators into smaller, finite, non-overlapping sets of tuples such as partitioned window groups, which incur less disk-access overhead. Second, we provide for the capability of continuous operators to correctly process out of order tuples using punctuation pointers. Third, we design methods for downstream operators to synchronize their processing stages with those of upstream operators to achieve optimized query plan throughput. Putting these techniques together, we have designed a consolidated spilling adaptation strategy which considers all aspects of operators' inter-connections in a query plan for making optimal adaptation decisions. The effectiveness of our integrated approach was empirically tested in a comparative evaluation study against several alternate spilling adaptation strategies. We conducted our experiments on CAPE, a DSMS developed at WPI, using different types of query plans composed of multiple partitioned window join operators. Our experiments prove that despite the higher overhead of a more synchronized adaptation approach, our consolidated strategy provides better query plan performance and higher plan throughput during periods of continuous bursts of high data rates.

Cette thèse a pour objet les politiques d'adaptation au changement climatique. Il est montré que la Convention-cadre sur le changement climatique (1992), ainsi que la construction des stratégies de réponse, sont caractéristiques d'une approche pollutioniste. Cette approche a conduit à appréhender la question du changement climatique comme un problème classique de pollution et d'environnement. Il en est résulté un double biais en défaveur de l'adaptation par rapport aux politiques d'atténuation : l'adaptation a été confinée dans un rôle secondaire et marginal dans la structuration des politiques, avec un cadre conceptuel et méthodologique inopérationnel pour sa mise en œuvre. La thèse propose une déconstruction de cette conception du changement climatique ; les limites majeures qui caractérisent les politiques d'atténuation remettant par ailleurs en cause la prépondérance qui leur a été accordée. La déconstruction de cette approche pollutioniste permet tout d'abord de montrer que la définition et l'opérationnalisation de stratégies d'adaptation efficaces nécessitent de dépasser (i) le cadre analytique standard des politiques climatiques et, (ii) la conception du changement climatique comme une question de pollution classique et de gestion de l'environnement. Il est alors soutenu que l'adaptation doit être inscrite dans la promotion du développement, c'est-à-dire qu'elle doit être appréhendée non plus dans une problématique de gestion ad hoc des effets d'une pollution mais dans une problématique de développement. Que ce soit dans le contexte propre aux politiques d'adaptation, ou plus largement dans celui des politiques climatiques, la thèse laisse cependant ouverte les questions relatives à la viabilité et aux modalités d'organisation et de financement d'un régime climat inscrit dans la promotion du développement. / Climate change adaptation policies are the subject of this thesis. It has been showed that the United Nations Framework Convention on Climate Change (1992) and the response strategies construction are characteristic of a pollutionist approach. This approach led to envision the question of climate change as a classic pollution and environment issue. As a result, this approach has generated a double bias to the disadvantage of adaptation compared to mitigation policies: adaptation has been confined in a secondary and marginal role in climate policies structuring, and with an inoperative conceptual and methodological framework for its implementation. The thesis proposes a deconstruction of this climate change conceptualization. Moreover, the major limits that characterize mitigation policies call into question the predominance given to them in climate policies construction. The « pollutionist » approach deconstruction allows at first to show that adaptation policies definition and operationalization need to go beyond (i) the standard analytic framework of climate policies and, (ii) the climate change conceptualization as a classic pollution and environment management issue. The thesis then argues that adaptation has to be integrated in development promoting policies, which means that adaptation needs to be conceptualized no longer as an ad hoc management of pollution effects issue, but as a development issue. Whether in the proper context of adaptation policies, or more largely of climate policies, the thesis leaves open the questions of the viability, but also of the organization and financing modalities, of a climate regime which fits within development promoting.