Efficient Phrase Querying with Common Phrase Index

In this paper, we propose a common phrase index as an efficient index structure to support phrase queries in a very large text database. Our structure is an extension of previous index structures for phrases and achieves better query efficiency with negligible extra storage cost. In our experimental evaluation, a common phrase index has 5% and 20% improvement in query time for the overall and large queries (queries of long phrases) respectively over an auxiliary nextword index. Moreover, it uses only 1% extra storage cost. Compared with an inverted index, our improvement is 40% and 72% for the overall and large queries respectively.