Re: Determine server version from psql script

Hi, Tom,

On Sat, Mar 22, 2025, 10:01 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Igor Korot <ikorot01(at)gmail(dot)com> writes:
> > On Sat, Mar 22, 2025, 8:58 PM David G. Johnston <
> david(dot)g(dot)johnston(at)gmail(dot)com>
> > wrote:
> >> Then read the psql docs. Your version has \if and you’ll find server
> >> version listed as the available client variables.
>
> > I was hoping for something like
>
> > If server_version >= X:
> > CREATE OR REPLACE TRIGGER...
>
> psql's \if doesn't (yet) have any native expression evaluation
> ability, so you have to farm out the ">=" comparison. The
> psql docs suggest relying on the server to do it, which would
> go along the lines of
>
> select current_setting('server_version_num')::int >= 130000 as v13
> \gset
> \if :v13
> ... do something
> \else
> ... do something else
> \endif
>

Thank for the code.

2 things, however.
1. Apparently CREATE OR RELACE TRIGGER syntax is available since v17, which
is the current one. So I hadto adjust the numbers.. 😀
2. Is there a way to do CREATE TRIGGER IF NOT EXIST for the earlier version?

Thank you.

>
> You could also do the comparison client-side, along the lines of
>
> \set v13 `expr :SERVER_VERSION_NUM \>= 130000`
> \if :v13
> ... etc
>
> But that introduces assorted platform dependencies and requires
> close attention to correct shell quoting, so it's seldom
> preferable IMO.
>
> regards, tom lane
>