Thread: parameter info?

What's the best way for me to find out if a given parameter of a 
function is a constant? The context is that it's expensive to process, 
and in most cases will in fact be a constant, so if it is in fact a 
constant I'd like to process it once and stash the results.

cheers

andrew

hello

2013/2/1 Andrew Dunstan <andrew@dunslane.net>:
>
> What's the best way for me to find out if a given parameter of a function is
> a constant? The context is that it's expensive to process, and in most cases
> will in fact be a constant, so if it is in fact a constant I'd like to
> process it once and stash the results.
>

you can look into parser tree

see src of get_fn_expr_argtype(fcinfo->flinfo, 0);

Regards

Pavel

> cheers
>
> andrew
>
>
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Andrew Dunstan <andrew@dunslane.net> writes:
> What's the best way for me to find out if a given parameter of a 
> function is a constant? The context is that it's expensive to process, 
> and in most cases will in fact be a constant, so if it is in fact a 
> constant I'd like to process it once and stash the results.

I think we added get_fn_expr_arg_stable() for precisely that
purpose.
        regards, tom lane

On 01/31/2013 11:17 PM, Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>> What's the best way for me to find out if a given parameter of a
>> function is a constant? The context is that it's expensive to process,
>> and in most cases will in fact be a constant, so if it is in fact a
>> constant I'd like to process it once and stash the results.
> I think we added get_fn_expr_arg_stable() for precisely that
> purpose.
>
>             


Thanks. That's exactly what I was looking for.

cheers

andrew