See also: IRC log
<Ashok> scribenick: hhalpin
<Ashok> scribe: Harry
<Ashok> PROPOSAL: Accept the minutes of last meeting, see > http://www.w3.org/2010/08/03-rdb2rdf-minutes.html >
Ashok: The plan of the meeting will be for Souri to finish the proposal, and then address comments.
<Souri> comments on Richard's comments: http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2010Aug/0013.html
Ashok: I think we have a reasonable agreement on the SQL-based approach, so we should see the next steps
Souri: Would prefer to go over the comments in detail first.
cygri: that's fine
cygri: I have a number of
... and then some expressivity requirements
... then some things for author convenience
... 1.1 don't include URI in pointed brackets
... souri seems to agree
1.2 a renaming away from property URI to instance URI map
<juansequeda> +1 for InstanceURIMap
cygri: I would prefer it to be called URI instance map
souri: I agree
cygri: 1.3 URI graph name
souri: let me explain, for each
column, the graph URI property name is one way of identifying
the graph with the column.
... we could avoid it as in previous treatment
... but richard points out you could have more property maps that generate the same names
... so we should need to keep the graph name
... for each property name we should have a backpointer that explains which graph URI name it goes with
... but once you have that, you really a name for the graph property
cygri: it appears that I may have
... I thought it referred to a RDF property
... but this may not have been your attention
... but what you just explained, that a property mapping has a mapping to a graph URI mapping
... then that's a design that I would be happy with.
juan: Could you give us an example?
juan: so the semantics of that are specified inside the URI?
Souri: It doesn't access the URI,
it's just the name of the graph
... so the syntax of the URI is not at all important.
cygri: my comment is that we can
easily duplicate information
... using keymaps
ericP: I'm projecting out 2 or 3
... if a particular column in one of the tables
... and that acts as a key
... in the regular database
souri: it's a very simple
approach, in fact, we've already simplified it in our
... so we identify a foreign key
... and then the key sequence also references this primary key
... now, foreign key can be any expression
... so in general, all we need to know that these columns are available
... that are used in some expression (x+y+2)
... but I realized we do not need the whole key definition
... all we really need
... is the name of the foreign key
... an object property name
... so we need to translate that.
... all we really need is the corresponding join condition
... we need the corresponding consequent.
... we need a template.
... but if it's a five column key, then we have five conditions, and so all we need from the mapping specifier is that template.
... which gives us a join condition for the foreign key
... which allows us to work through the aliases
ericP: So there are a class of functions that are reversible, but for those that aren't we have to materialize them
souri: that's not the issue
... imagine if x is exposed as f(x), but only x is exposed, but if the foreign key is f(x)=d(y), where d may not be reversible, but all we need is the info that f(x)=d(y) as that needs to be put in join condition
<ericP> Souri has convinced me that reversibility is not required for creating a join constraint; the engine will be evaluating this on specific tuples
cygri: I will study this
... Second set of points
... we need to have blank nodes as subjects
<ericP> (of course, non-reversibility leads to table scans, but that's not our problem)
cygri: different literals genreated from same property name could have different langauge tags
souri: I agree, good point
... the question is can we have it in the expression that generate the literal value that give it a language tag
<Souri> title || "@en-us"
cygri: my preference would be to keep it separate
souri: not sure if I agree
cygri: we don't have this in
... but no-one has ever asked for it.
ericP: For example, SPARQL 1.1 doesnt include dates but does handle datetimes
cygri: So it would be nice if typed literals could be contracted and specify an override for a datatype
<ericP> "2010-08-10"@date => "2010-08-10"^^xsd:dateTime
souri: but for computed data types how do we handle this?
cygri: we do need some kind of
... numbers in string columns
souri: I now agree with the importance, but not sure how to handle computed types, that's all.
ericP: we do not necessarily need to validate the types
cygri: flag this as open
... Entity value schema
... here are the attributes that the column actually represents
... we would want to map this attribute to different properties
... you seem to think this approach is OK.
... I remember
... there was a long e-mail from Orri from OpenLink that having computed property URIs is not a good idea.
... we might have a column with an extended data in another table
... we want numbers that identify the particular extent that specify the particular some readable text
... so having a lookup table is a good idea
souri: not sure if this is a good
... as imagine if the lookup table gets too big
... this may have impacts on the computation
cygri: we implemented it in
... and it worked in a straightforward manner
souri: I will update the wiki
Ashok: let's leave the rest for next week
cygri: he agreed with most of the rest of these.
Ashok: is this a reasonable
... are we headed towards a first public draft document?
sequada: Looks great, but we need to work on semantics
Ashok: No strong negatives
<LeeF> I'm wondering if we're going to talk about syntax before FPWD
<LeeF> because I think that's very important
cygri: I'm happy with
expressivity and general design
... some question about syntax
Ashok: let's talk about syntax last
juan: datatypes and generating
... myself and Marcelo are working on a semantics document
trackbot, end meeting
This is scribe.perl Revision: 1.135 of Date: 2009/03/02 03:52:20 Check for newer version at http://dev.w3.org/cvsweb/~checkout~/2002/scribe/ Guessing input format: RRSAgent_Text_Format (score 1.00) Succeeded: s/??/Orri from OpenLink/ Succeeded: s/extent/some readable text/ Succeeded: s/hospitality/data in another table/ Found ScribeNick: hhalpin Found Scribe: Harry Default Present: Souri, soeren, juansequeda, cygri, Ashok_Malhotra, MacTed, hhalpin, LeeF, EricP, Souri_Das Present: Ashok Richard EricP Harry Ivan Juan LeeF Ted Soeren Souri Regrets: Boris Marcelo Got date from IRC log name: 10 Aug 2010 Guessing minutes URL: http://www.w3.org/2010/08/10-rdb2rdf-minutes.html People with action items:[End of scribe.perl diagnostic output]