Re: [Rdfapi-php-interest] ORDER BY (different data types)

[Christian W. <cw...@cw...>]

Andy,


>> I doubt that I can change the schema since many other parts of rdfapi
>> use it.=20
> That makes it tricky - isn't there a singel abstraction layer that hand=
les all RDF->DB mapping?
There is a working one, but it is really slow when handling thousands or
millions of statements since all reasoning is done offline, i.e. on the
client side instead of the database.

My task is to create a Sparql-to-DB-Enginge that does as much as
possible directly on the database server. It seems that sorting is a
thing that can only be done on client side.


I also came up with another idea:
When having a ORDER BY statement, query the database first to get a
DISTINCT list of datatypes in the result set. If there is only one type
of data, use a ORDER BY CAST(..) in the main query. If there are
multiple datatypes, or no suitable cast type exists, sorting has to be
done on client side.
I don't know how fast it is to make two queries instead of one, but
should still be a lot faster when working on millions of rows than
sorting client side.


--=20
Regards/Mit freundlichen Gr=FC=DFen
Christian Weiske