Patent ID: 8229970
Filing Date: 2012-07-24
Classification: G06F

Abstract:
1. A computer-implemented method for storing and retrieving one or more posting lists from a physical storage medium, the method comprising performing computer-implemented operations for: storing a hierarchy of semantic roles comprising a role tree having nodes related to one another in a strict dominance hierarchy, each of the nodes in the role tree corresponding to a semantic role and being associated with one or more terms; generating a posting list for each association of a term and a semantic role in the hierarchy, each posting list comprising data identifying one or more documents that include the usage of the term in the associated semantic role; storing the posting lists contiguously on a physical storage medium by performing a pre-order depth-first traversal of the nodes of the role tree, and at each of the nodes, writing the posting list for a term associated with the semantic role corresponding to the node to the physical storage medium; storing data in a lexicon indicating a starting position for the posting list for each association of a term and a semantic role in the hierarchy and data indicating a total size of the posting lists under each node of the role tree; retrieving the data from the lexicon identifying the starting position on the physical storage medium for a term at a top of a desired subtree of the hierarchy; retrieving the data from the lexicon identifying the total length of posting lists of the desired subtree of the hierarchy; and loading a single contiguous block from the starting position on the physical storage medium through the length, the single contiguous block including the posting lists for the desired subtree of the hierarchy.