Re: [Firebird-devel] HASH function (CORE-4436)

[Adriano d. S. F. <adr...@gm...>]

Em 18/07/2017 17:35, Vlad Khorsun via Firebird-devel escreveu:

> 
>   Algorithm name could define result length.

Yes, for constants.


> If alg name is passed as
> parameter, we could use maximum known length (of all known algs) at
> prepare time.
> 

Maximum known length means if a new algorithm is added, it will be
increased and that seems not good. It may break applications.

Firebird has a interesting but unused feature, which is:

- A system function can declare a fixed length, say VARCHAR(20)

- Actual function execution can return VARCHAR(30)

- User CAST function execution to return VARCHAR(30)

- It works! :)


Adriano