feat: add types for cds.ql.SELECT.hints()

[schwma]

part of cdsnode/issues/2186

see docs: cap-js/docs#1619

[daogrady]

Hi Marcel,

thanks for the contribution, looks pretty good! Can hints be any arbitrary string, or do we have a list of valid values (IGNORE_PLAN_CACHE, ...) that can be passed into this parameter?

Best,
Daniel

[schwma]

Hi @daogrady,

No, we do not have a list of valid hint strings. Any arbitrary string can be passed as an argument.

Best regards,
Marcel

[johannes-vogel]

it's basically all hints which are in hana docs: https://help.sap.com/docs/SAP_HANA_PLATFORM/4fe29514fd584807ac9f2a04f6754767/4ba9edce1f2347a0b9fcda99879c17a1.html?locale=en-US&state=PRODUCTION&version=2.0.08

but that list is growing.

[daogrady]

If it really is restricted to a fixed list of strings, even if that list is in flux, then I'd be in favour of explicitly listing these strings. Maybe another package provides them already, or we can automatically keep the list up to date.

If, of course, users can define arbitrary flags they can come up with in their personal project, then string is absolutely fine.

[johannes-vogel]

The strings are dynamic e. g. CALL P1() WITH HINT( ROUTE_BY_CARDINALITY(T1,T2,T3)); while T1,T2,T3 refer to tables

[daogrady]

That can also be expressed, but I guess it strongly depends on much auto-completion/ type safety we want to provide the users with at this particular point. Ultimately you (as in: "the runtime team") have to make that call. 🙂