Medha GRIN Presentation Gregory Todd Williams 1

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• Question is for the Presentation: Medha GRIN Presentation
• Question is asked by: Gregory Todd Williams
• The Question is: Reducing the potential graph data used in matching by traversing the index tree seems to rely on a sufficient number of query constraints. These constraints, however, seem to rely on the query using a number of bound subjects or objects. Would queries with few (or no) bound subjects or objects eliminate the effective use of the GRIN index?

Since no details are given on the queries used in the evaluation, it's hard to know how the GRIN approach would perform on such queries (where you might be querying for the subjects and objects, using bound predicates to define the query pattern). Relatedly, these are exactly the queries where the other systems used in the evaluation might perform better than GRIN, since the increased index creation time and size of these systems are likely a result of indexing for, in part, patterns with only predicates bound.

• Answer: Yes you are right. The constraints are extracted from graph and seem to rely on at least some bound nodes in the query graph.

Your doubt about details of the queries used for evaluation is correct. There are no details given w.r.t. the standard size of query graph used in the evaluation and effectiveness of GRIN index on different queries and query graph sizes.

I believe it is fair to assume by a given query graph will have some bound nodes, as most realistic queries do have some bound nodes.