Re: [PATCH] Fix duplicate errmsg in ALTER TABLE SPLIT PARTITION - Mailing list pgsql-hackers

On Wed, Apr 29, 2026 at 5:03 PM Ayush Tiwari
<ayushtiwari.slg01@gmail.com> wrote:
>   - For SPLIT, switch the adjacency error to
>         errmsg("cannot split partition \"%s\"",
>                get_rel_name(splitPartOid)),
>     so it names the old partition, matching the merge wording style.
>     To make splitPartOid available there, I added an Oid splitPartOid
>     parameter to check_two_partitions_bounds_range() and pass
>     InvalidOid from the merge call site (where is_merge is true so
>     the parameter is unused).

If we have splitPartOid, then the boolean is_merge is redundant and
can be removed, right? To keep the intent clear we can add a local
variable

bool is_merge = (splitPartOid == NULL ? true : false);

Other than that, both patches LGTM.

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?

--
John Naylor
Amazon Web Services