Re: Is pgAdmin the only front-end to PostgreSQL debugger ? And is "a working pl/pgsql debugger" something core should care to maintain ?

Hi

čt 13. 2. 2025 v 18:00 odesílatel Hannu Krosing <hannuk(at)google(dot)com> napsal:

> Hallo PostgreSQL Hackers,
>
>
> We recently discovered an error where pgAdmin fails when stepping into
> nested function calls (
> https://github.com/pgadmin-org/pgadmin4/issues/8443 ).
>
> So while waiting for this to be fixed I would want to know if there
> are other debugger front-ends that could be used to do basic debugging
> of pl/pgsql code ?

If I remember, there was a independent application that was a plpgsql
debugger, but it was in time before pgadmin 4

Maybe dbeaver uses it too. I think some commercial gui has support for
debugging plpgsql, but I am not sure that it is.

>
> And would these need a separate debugging extension, or is "debugging"
> meant to be a generic PostgreSQL server feature that has a
> well-defined API ?
>

Unfortunately buildin API has not external interface. So everytime you
need an extension that use internal plpgsql debug API or allow a access to
some plpgsql data like stack or variables.

These extensions can be different, - plpgsql_check uses these API,
plprofiler or pldebugger

If I remember well, the development of pldebugger or plprofiler was a fully
independent project on Postgres core, and there was not any attempt to
merge it upstream.

The internal buildin part is really minimalistic - just few hooks

> I know there used to be another debugger as part of OmniDB which had
> its own server-side extension as well, but wanted to know what is the
> general thinking on this.
>
> Is debugging pl/pgsq a generic feature of PostgreSQL core considering
> that pl/pgsql itself kind of is ?
>

debugging plpgsql is independent of the PostgreSQL core.

> Should there be something similar for debugging plain SQL and possibly
> other PL languages?
>

I can imagine this - there can be some common API supported by language
handlers.

>
> Should there perhaps be debugging support in psql ?
>

psql does not support asynchronous API, so the implementation in psql
really should not be simple. Moreover, I doubt that users want to use a
debugger with a GUI similar to gdb. And it isn't possible to design a
better UI directly in psql. I can imagine supporting some external
debuggers executed inside / or outside the same terminal that communicates
with psql by some bidirect pipe (psql will be used like a proxy). Then can
be designed some application similar to Borland debugger. This can be a
very nice feature with probably not too much code, but handling bidirect
pipes isn't trivial. Tuning reading from pipe for pspg for some less usual
patterns was not nice work (and there the communication is significantly
more simple than for debugger).

Regards

Pavel

>
> ------
> Hannu
>
>
>