Raised by @bna on slack. I’d suggest basing this on Aql: clarify types supported by relational operators Copying my response from slack: ORDER BY is closely related to this since we can define it as based on the result of the relational operator x < y. So the RM types within the scope of ORDER by w…

As a first simplification, we could say “ORDER BY could be specified only over simple types like numbers and strings” and put some examples in the spec. Then discuss if that is enough or if we really need to order by an openEHR DV, which have multiple attributes and the AQL processor will really be …

[image] pablo: IMO the only thing we gain from ordering by a DV is to write a little shorter path, but at the price of making AQL processors, and the AQL spec, more complex. Maybe not - as long as the ‘<’ operator is defined on any type (which it is in the openEHR DV_ORDERED types), then any …

yep. what I’m saying is define order by in terms of ‘definition(s) of relational operator(s)’ and you have both consistency and simplicity.

[image] thomas.beale: Maybe not - as long as the ‘<’ operator is defined on any type I agree, but that will take some time for some types that have “accuracy” ans discussed on today’s meeting. Maybe we can break this into two issues, first specify ORDER BY for simple/assumed types **, then wh…

[image] thomas.beale: any ordering is easy enough to implement Yes, when handwaving. No, when real world hits you with its performance requirements. I agree with @pablo ’s statement that there’s not much value added for customers, so I don’t think this pays off.

[image] matijap: Yes, when handwaving. No, when real world hits you with its performance requirements. I agree with @pablo ’s statement that there’s not much value added for customers, so I don’t think this pays off. I fully support this. The reason why I am boring you with this is the require…

[image] matijap: Yes, when handwaving. No, when real world hits you with its performance requirements. I agree with @pablo ’s statement that there’s not much value added for customers, so I don’t think this pays off. Not sure what you mean here. I assume we agree that we want ordering on the O…

[image] thomas.beale: Not sure what you mean here. I mean it’s easy to have two instances of some type or other and implement comparison any way specification defines, and it’s easy to do this for any defined type, and it’s easy to implement a generic method that takes two objects and determi…

Ok - so I think you are talking performance optimisation. I would have thought that approaches to that would include being able to access more or less any fragment of code from a main library (in Java, C# etc) from a ‘stored procedure’ invocation, which is possible for some years in Postgresql and I…

Of course my point of view is impacted by implementation considerations as well. :slight_smile: If I saw it as something very beneficial for users, I’d be pushing it, but I really don’t. We’ll spend a lot of time discussing how to compare quantities or durations, and at the end the query authors won…

AQL: Clarify types to be supported by ORDER BY

Specifications AQL

sebastian.iancu (Sebastian Iancu) 19 February 2020 13:28 13

just for future references, i will cross-link this here: Aql: clarify types supported by relational operators

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AQL: Clarify types to be supported by ORDER BY

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