- From: RDB2RDF Working Group Issue Tracker <sysbot+tracker@w3.org>
- Date: Fri, 30 Sep 2011 14:36:09 +0000
- To: public-rdb2rdf-wg@w3.org
ISSUE-69 (datatype sizes): datatype sizes
http://www.w3.org/2001/sw/rdb2rdf/track/issues/69
Raised by: Eric Prud'hommeaux
On product:
http://www.w3.org/2001/sw/rdb2rdf/track/issues/48 was resolved by following the SQL spec's lead for generating XML from SQL datatypes. Unfortunately, these mappings are all subject to vender-specific width limitations, which means that implementors have no idea what to implement in order to interoperate with other implementations. The Direct Mapping LC provides fixed numbers for these mappings,
http://www.w3.org/TR/2011/WD-rdb-direct-mapping-20110920/#defn-literal_map
but these have not been subject to WG review. Justifications for these selections were:
type width reason
xsd:decimal 18 http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#decimal says minimum is 18
xsd:integer 18 lexical restriction of decimal doesn't affect width
xsd:double 23 maximum characters for an IEEE754 double (i.e. xsd:double)
xsd:date 13 limited to under 100k years, e.g. +100000-01-01
xsd:time 23 10E-14 second precision, e.g. 01:23:45.67890123456789
xsd:dateTime 37 sizeof(xsd:date)+sizeof("T")+sizeof(xsd:time)
The choices of 10E6 years and 10E-14 seconds are arbitrary. We could limit to common cases like CCYY for years, and microsecond precision for time, noting that extensions to dates should follow the conventions in ISO8601. That would reduce widths to 10 and 15, putting dateTimes as 26.
Received on Friday, 30 September 2011 14:36:10 UTC