Re: extend pgbench expressions with functions

On Fri, Sep 18, 2015 at 10:21 AM, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> wrote:

>
> Hello Kyotaro-san,
>
> My description should have been obscure. Indeed the call tree is
>> finite for *sane* expression node. But it makes infinit call for
>> a value of expr->etype unknown by both evalDouble and
>> evalInt.
>>
>
> Such issue would be detected if the function is actually tested, hopefully
> this should be the case... :-)
>
> However I agree that relying implicitely on the "default" case is not very
> good practice, so I updated the code in the attached v11 to fail
> explicitely on such errors.
>
> I also attached a small test script, which exercises most (all?) functions:
>
> ./pgbench -f functions.sql -t 1
>

A short review from me:

1. Patch applies cleanly on current HEAD.
2. It compiles without errors or warnings.
3. The attached test case can be executed w/o symptoms of any problem and
it produces meaningful results.

Should we not allow for functions taking 0 arguments? Since we're already
into some math here, how about pi()? ;-)

I understand requiring at least 1 arg simplifies the code a bit, but right
now it reports syntax error for "random()", while it correctly reports
unexpected number of arguments for "random(1,2,3)". We would need another
check for min() and max() which expect >=1 arguments, but it's easy to add.

I would also argue that we should rename "random" to "rand" here to avoid
confusion with the familiar SQL function "random()" that doesn't take
arguments.

--
Alex