Abstract: There are various overlay structures that provide
efficient and scalable solutions for point and range query in a peer-topeer
network. Overlay structure based on m-Binary Search Tree
(BST) is one such popular technique. It deals with the division of the
tree into different key intervals and then assigning the key intervals to
a BST. The popularity of the BST makes this overlay structure
vulnerable to different kinds of attacks. Here we present four such
possible attacks namely index poisoning attack, eclipse attack,
pollution attack and syn flooding attack. The functionality of BST is
affected by these attacks. We also provide different security
techniques that can be applied against these attacks.
Abstract: Semantic query optimization consists in restricting the
search space in order to reduce the set of objects of interest for a
query. This paper presents an indexing method based on UB-trees
and a static analysis of the constraints associated to the views of the
database and to any constraint expressed on attributes. The result of
the static analysis is a partitioning of the object space into disjoint
blocks. Through Space Filling Curve (SFC) techniques, each
fragment (block) of the partition is assigned a unique identifier,
enabling the efficient indexing of fragments by UB-trees. The search
space corresponding to a range query is restricted to a subset of the
blocks of the partition. This approach has been developed in the
context of a KB-DBMS but it can be applied to any relational
system.