I actually already implemented support in SPARQL for that, but it needs a bit more work to get it properly merged with the Blazegraph code.  I had it working for a while as part of Sophox (OSM Sparql).

* docs:  https://wiki.openstreetmap.org/wiki/Sophox#External_Data_Sources
* code:  https://github.com/Sophox/wikidata-query-rdf/compare/master...Sophox:tabular
(see Tabular* files)
* phabricator discussion about the above code:  https://phabricator.wikimedia.org/T181319

Tabular support allows any CSV-style tables to be treated as federated sources. With minor changes it should be possible to use mediawiki's .tab pages too.

On Fri, May 31, 2019 at 6:01 PM Daniel Mietchen <daniel.mietchen@googlemail.com> wrote:
I'm looking into ways to use tabular data like
in SPARQL queries but could not find anything on that.

My motivation here is in part coming from the time out limits, and the
basic idea here would be to split queries that typically time out into
sets of queries that do not time out and - if their results were
aggregated - would yield the results that would be expected for the
original query would it not time out.

The second line of motivation here is that of keeping track of how
things develop over time, which would be interesting for both content
and maintenance queries as well as usage of things like classes,
references, lexemes or properties.

I would appreciate any pointers or thoughts on the matter.



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