Re: [PATCH] Fix duplicate errmsg in ALTER TABLE SPLIT PARTITION

On Tue, May 5, 2026 at 3:15 PM John Naylor <johncnaylorls(at)gmail(dot)com> wrote:
>
> Observation:
>
> - errmsg("can not split non-DEFAULT partition \"%s\"",
> + errmsg("cannot split non-DEFAULT partition \"%s\"",
> get_rel_name(splitPartOid)),
> - errmsg("new partition cannot be DEFAULT because...
> + errdetail("New partition cannot be DEFAULT because...
>
> -ERROR: new partition cannot be DEFAULT because DEFAULT partition
> "sales_others" already exists
> +ERROR: cannot split non-DEFAULT partition "sales_all"
> LINE 5: PARTITION sales_others2 DEFAULT);
> ^
> +DETAIL: New partition cannot be DEFAULT because DEFAULT partition
> "sales_others" already exists.
>
> If there are two errmsg's back-to-back, only the second one displays.
> Maybe some automated tooling can detect cases like this going forward?
>

Add an Assert in function errmsg, it will crashes the server when two
errmsg back-to-back:

Assert(edata->message == NULL);
EVALUATE_MESSAGE(edata->domain, message, false, true);

Function FreeErrorDataContents change to
```
if (edata->message)
{
pfree(edata->message);
edata->message = NULL;
}
```

Most of the tests succeeded on my local machines.
Ok: 373
Expected Fail: 0
Fail: 0
Unexpected Pass: 0
Skipped: 23
Timeout: 0

I'm not sure if ereport_domain acts differently when
HAVE_PG_INTEGER_CONSTANT_P is true.

--
jian
https://www.enterprisedb.com/