Re: psql: add \create_function command

On Fri, Jan 26, 2024 at 12:23 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

>
> \set fbody `cat source_file.txt`
> CREATE FUNCTION foo() RETURNS whatever AS :'fbody' LANGUAGE ...;
>
> and maybe we should say that that's sufficient.

I really don't have a problem, and kinda prefer, using psql variables this
way but feel much more comfortable not having to invoke a shell.

> It's a bit
> klugy though. One level of improvement could be to get rid
> of the dependency on "cat" by inventing a backslash command
> to read a file into a variable:
>
> \file_read fbody source_file.txt
>

This I would use to reliably read external json text files into a psql
variable so that I could use jsonb_to_recordset(:var) on the contents.

> (\file_write to go the other way seems potentially useful too.)
>

The nearby discussions regarding trying to produce json into files would
support this claim.

> Or we could cut out the intermediate variable altogether
> by inventing something that works like :'...' but reads
> from a file not a variable. That might be too specialized
> though, and I'm not sure about good syntax for it either.
> Maybe like
>
> CREATE FUNCTION foo() RETURNS whatever AS :{source_file.txt} LANGUAGE ...;
>
>
IMO, not enough improvement to be had over letting psql variables act as
the intermediary to justify the effort.

David J.