Re: Patch for 8.5, transformationHook

2009/4/20 Peter Eisentraut <peter_e@gmx.net>:
> On Sunday 19 April 2009 20:47:37 Pavel Stehule wrote:
>> 2009/4/19 Peter Eisentraut <peter_e@gmx.net>:
>> > On Saturday 18 April 2009 18:09:00 Pavel Stehule wrote:
>> >> There are lot of things, that should be done with current grammar only
>> >> on transformation stage. Currently pg do it now. There are lot of
>> >> pseudo functions, that are specially transformed: least, greatest,
>> >> coalesce. After hooking we should do some similar work from outer
>> >> libraries.
>> >
>> > There are surely other ways to accomplish this than an expression
>> > transformation hook.  Adding a property or two to the function definition
>> > to do what you want could do it.
>>
>> should you describe it little bit more?
>
> The question we should be asking is, what is it that prevents us from
> implementing least, greatest, and coalesce in user space now?  And then design
> a solution for that, if we wanted to pursue this.  Instead of writing
> transformation hooks and then force every problem to fit that solution.
>

I don't believe so is possible to find other general solution. (or
better I didn't find any other solution). Tom has true,
transformationHook on expression is expensive. I thing, so hook on
function should be simple and fast - not all transformation's should
be simple defined via property - classic sample is "decode" like
functions, it needs procedural code.

regards
Pavel Stehule