Efficient incremental evaluation of succinct regular expressions

• Regular expressions are omnipresent in database applications. They form the structural core of schema languages for XML, they are a fundamental ingredient for navigational queries in graph databases, and are being considered in languages for upcoming technologies such as schema- and transformation languages for tabular data on the Web. In this paper we study the usage and effectiveness of the counting operator (or: limited repetition) in regular expressions. The counting operator is a popular extension which is part of the POSIX standard and therefore also present in regular expressions in grep, Java, Python, Perl, and Ruby. In a database context, expressions with counting appear in XML Schema and languages for querying graphs such as SPARQL 1.1 and Cypher.We first present a practical study that suggests that counters are extensively used in practice. We then investigate evaluation methods for such expressions and develop a new algorithm for efficient incremental evaluation. Finally, we conduct an extensive benchmark study that shows that exploiting counting operators can lead to speed-ups of several orders of magnitude in a wide range of settings: normal and incremental evaluation on synthetic and real expressions.

Ämnesord

NATURVETENSKAP  -- Data- och informationsvetenskap -- Datavetenskap (hsv//swe)

NATURAL SCIENCES  -- Computer and Information Sciences -- Computer Sciences (hsv//eng)

Nyckelord

XML

Schema

Regular Expressions

Publikations- och innehållstyp

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