When WebDAV resources of supported content types are stored into the Virtuoso repository, metadata is automatically extracted. This metadata is also published as a SPARQL queriable graph. All public readable resources in WebDAV have their owner, create time, update time, size and tags published, plus whatever content type dependent metadata there is.
This metadata is accessible through the URIQA protocol and now via the SPARQL protocol endpoint. Naturally, any SQL query can also access this, since SPARQL can be freely intermixed with SQL.