- From: Phil Dawes <pdawes@users.sourceforge.net>
- Date: Tue, 11 May 2004 17:50:16 +0100
- To: "Seaborne, Andy" <andy.seaborne@hp.com>
- Cc: www-rdf-interest@w3.org
Hi Andy, Hi All, An area where I've found RDQL a little underspecified is in the syntax for regex searches. RAP encloses the regex in quotes (e.g. "/regex/"), I'm not sure what sesame does, and Jena regexes must be unquoted (e.g. /regex/). Unfortunately the grammar in the spec doesn't specify this so I'm not sure which is 'correct'. While I'm on the subject, the other unfortunate thing about RDQL pattern searches is that most relational databases don't support regexes and so for rdb backed stores the filtering has to be done in-memory. Unfortunately the most common usage of this feature for me is to do a global label search, which involves e.g. SELECT ?subj, ?label WHERE (?subj,<rdfs:label>,?label) AND ?label =~ '/phi/i' This is obviously a bit of a problem to do in-memory for large stores. Is there potentual for a more restricted form of pattern in RDQL that could be done in-database? e.g. something like SeRQLs 'LIKE' clause (for those unfamiliar with seRQL/sesame, this does a case-insensitive match with a single wildcard character '*' which matches zero or more characters - this nicely mapps to LIKE and % in SQL). Cheers, Phil
Received on Tuesday, 11 May 2004 12:51:10 UTC