Re: SPI/backend equivalent of extended-query Describe(statement)?

2018-05-14 17:29 GMT+02:00 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:

> Chapman Flack <chap(at)anastigmatix(dot)net> writes:
> > The longer version of $subject is: how would one go about, in the
> > backend using SPI (or SPI and maybe other server APIs as needed),
> > obtaining the same inferred parameter information that a front-end
> > client can get with the Describe (statement variant) extended-query
> > message?
>
> If you're talking about the plan's input parameters, don't SPI_getargcount
> and SPI_getargtypeid do what you need?
>
> If you want to know about the output column types, SPI doesn't seem to
> have a nice way of getting that in advance of execution, but you could
> emulate what Describe does:
>
> * Use SPI_plan_get_plan_sources to get a list of CachedPlanSources
> (up to you to decide what to do if there's more or less than one CPS)
>
> * For each/selected CPS, look at the resultDesc and/or targetlist
> similarly to SendRowDescriptionMessage.
>

plpgsql_check does this work more times

see source code https://github.com/okbob/plpgsql_check

Regards

Pavel

>
> regards, tom lane
>
>