Re: Improving PL/Tcl's error context reports

čt 4. 7. 2024 v 19:36 odesílatel Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> napsal:

> Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
> > čt 4. 7. 2024 v 17:27 odesílatel Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
> > napsal:
> >> What happens if you rename a function? I guess the error context will
> >> still print the old name, but that's pretty harmless.
>
> > The rename should to generate different tid, so the function will be
> > recompiled
>
> Right. With patch:
>
> regression=# create function bogus() returns int language pltcl as
> 'return [expr 1 / 0]';
> CREATE FUNCTION
> regression=# select bogus();
> ERROR: divide by zero
> CONTEXT: while executing
> "expr 1 / 0"
> (procedure "__PLTcl_proc_bogus" line 2)
> invoked from within
> "__PLTcl_proc_bogus"
> in PL/Tcl function "bogus"
> regression=# alter function bogus() rename to stillbogus;
> ALTER FUNCTION
> regression=# select stillbogus();
> ERROR: divide by zero
> CONTEXT: while executing
> "expr 1 / 0"
> (procedure "__PLTcl_proc_stillbogus" line 2)
> invoked from within
> "__PLTcl_proc_stillbogus"
> in PL/Tcl function "stillbogus"
>
> >> Hmm, could we do something with tcl namespaces to allow having two
> >> procedures with the same name? E.g. create a separate namespace, based
> >> on the OID, for each procedure. I wonder how the stack trace would look
> >> like then.
>
> If the namespace depends on the OID then we still have nonreproducible
> stack traces, no? We could maybe make Tcl namespaces that match the
> SQL schema names, but that doesn't get us out of the duplication
> problem when there are similarly-named functions with different
> argument lists.
>
> Another idea is to make the Tcl names include the SQL schema name,
> that is __PLTcl_proc_myschema_myfunction. That avoids needing to
> append OIDs when the problem is functions in different schemas,
> but it doesn't move the needle for overloaded functions. On the
> whole I feel like that'd add verbosity without buying much.
>

I like the idea of using a schema name inside. It doesn't fix all, but the
cost can be low, and some risk of duplicity is reduced.

Getting unique name based on suffix _oid looks not too much nice (using
_increment can be nicer), but it should to work

PLpgSQL uses more often function signature

(2024-07-04 19:49:20) postgres=# select bx(0);
ERROR: division by zero
CONTEXT: PL/pgSQL function fx(integer) line 1 at RETURN
PL/pgSQL function bx(integer) line 1 at RETURN

What can be interesting information

How much work can be using modified function signature for internal name
like

__PLTcl_proc_myschema_myfunction_integer

__PLTcl_trigger_myschema_myfunction_table_schema_table

Is there some size limit for variable name? I didn't find it.

> regards, tom lane
>