BOOMER: Blending visual formulation and processing of P-homomorphic queries on large networks

Visual graph query interfaces (a.k.a gui) make it easy for non-expert users to query graphs. Recent research has laid out and implemented a vision of a novel subgraph query processing paradigm where the latency offered by the gui is exploited to blend visual query construction and processing by generating and refining candidate result matches iteratively during query formulation. This paradigm brings in several potential benefits such as superior system response time (srt) and opportunities to enhance usability of graph databases. However, these early efforts focused on subgraph isomorphismbased graph queries where blending is performed by iterative edgeto-edge mapping. In this paper, we explore how this vision can be realized for more generic but complex 1-1 p-homomorphic (phom) queries introduced by Fan et al. A 1-1 p-hom query maps an edge of the query to paths in the data graph. We present a novel framework called Boomer for blending bounded 1-1 p-hom (bph) queries, a variant of 1-1 p-hom where the length of the path is bounded instead of arbitrary length. Our framework is based on a novel online, adaptive indexing scheme called cap index.We present two strategies for cap index construction, immediate and defermentbased, and show how they can be utilized to facilitate judicious interleaving of visual bph query formulation and query processing. Boomer is also amenable to modifications to a bph query during visual formulation. Experiments on real-world datasets demonstrate both efficiency and effectiveness of Boomer for realizing the visual querying paradigm on an important type of graph query.