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Goals and Contributions 1. Produce a visual interface to formulate a query by clicking-and-dragging items 6 4/12/2013
Goals and Contributions Improve System Response Time They blend Visual Query Construction and Query Processing Use the latency of Query production to process current part of query. Start query processing before the user hits the RUN button They assume user doesn’t make mistake during the query formulation (doesn’t UNDO) 7 4/12/2013
Challenges How to mix query construction and evaluation with MINIMAL DISK ACCESS How to Index the data How to make the pre-fetch processing transparent from the user 8 4/12/2013
Overview: Indexing action-aware frequent index (A2F) Use Preprocessing action-aware infrequent index (A2I) If the final query is infrequent, probe A2I 9 4/12/2013
Indexing Because of the visual interface structure, the query size is grown by one in each step. The indexing has to (given a list of graphs that satisfy the fragment ′ in Step ) to support efficient strategy for identifyingthe graphs that match the fragment ′′ (generated at Step + 1) 17 4/12/2013
A2F index Being able to fit the matches in the memory , Frequent indices are divide to Memory-Resident and Disk-Resident Smaller frequent fragments are processed more frequently in various visual queries Smaller fragments have more matches If |g|< (threshold) it is saved in memory (MF-index) otherwise it is saved in the disk (DF-index) 18 4/12/2013