Optimization of Declarative Sensor Network Queries

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SUMMARY 1)FOR “COMPREHENSIVE OPTIMIZATION OF DECLARATIVE SENSOR NETWORK QUERIES” To be very precise the research paper deals with the issues of achieving optimization of declarative sensor network queries.As represented by the paper,sensor networks like ad-hoc and wireless networks are energy constrained and because of these restrictions it is very difficult to achieve the aim stated above.The approach or the technique used to solve the problem is adapting the DQP(distributed query processing) i.e TWO PHASE OPTIMIZATION and theories related to it. ANALYSIS Basically the fact that sensor networks have many exceptions have led to many problems when it comes to optimizing queries.Pertaining to this fact its always been one of the most discussed topic in database management system.Initially the concept which somehow provided the solution for this problem is TINYDB.The TINYDB query language is basically a declarative SQL-like query language supporting selection ,join,projection and aggregation.It doesn’t discriminates between different sensors and counts the entire collection as a single relation with different attributes like tempreatutre,pressur etc. and for that for that purpose there is a different sensor.But the problem lies is that optimization is limited to operator reordering and the use of cost models to determine an appropriate acquisition rate.so a new solution was required.So the technical approach used was the implementation of two-phase optimization approach i.e DQP.It is centralized,distributed as well as hybrid and the result were quite convincing.Tthe issues and challenges which arrived while implementing the DQP approach for sensor networks were the issues which were violated in sensor networks.Those issues were related to sensors major ones being that sensors are energy constraint,they act in a way as to preserve energy so as to maintain the network longevity and code is implemented in a way so the higher energy tasks are discarded or delayed.Another issue which comes into highlight is that the communication links are distance sensitive and an altogether a new topology is followed for the transfer of the data and also the need to run sensor nodes according to data-dependent duty cycles.Now about the technical approach which has been deviced to deal with the issues and challenges which have arrived in the paper.firstly there have been a few technical assumptions before implementing the real technique like the sensor networks are self organizing and they tend to identify their neighbours nodes and establish a link between them on their own.They are implemented so as to be risk free and hence can be re-established in case of failure.

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