Re: ON CONFLICT DO SELECT (take 3)

On Mon, Nov 24, 2025 at 11:23 PM Viktor Holmberg <v@viktorh.net> wrote:

It did not. But this will.
For some reason, in this bit:

‘''
LockTupleMode lockmode;
….
case LCS_FORUPDATE:
lockmode = LockTupleExclusive;
break;
case LCS_NONE:
elog(ERROR, "unexpected lock strength %d", lockStrength);
}

if (!ExecOnConflictLockRow(context, existing, conflictTid,
resultRelInfo->ri_RelationDesc, lockmode, false))
return false;
‘''

GCC gives warning "error: ‘lockmode’ may be used uninitialized”. But if I switch the final exhaustive “case" to a “default” the warning goes away. Strange, if anyone know how to fix let me know. But also I don’t think it’s a big deal.

hi.
you can search ``/* keep compiler quiet */`` within the codebase.

after
``elog(ERROR, "unexpected lock strength %d", lockStrength);``
you can add
``
lockmode = LockTupleExclusive;
break;
``

in doc/src/sgml/mvcc.sgml:
<para>
<command>INSERT</command> with an <literal>ON CONFLICT DO
NOTHING</literal> clause may have insertion not proceed for a row due to
the outcome of another transaction whose effects are not visible
to the <command>INSERT</command> snapshot. Again, this is only
the case in Read Committed mode.
</para>
I think we need to add something after the above quoted paragraph.

doc/src/sgml/ref/create_view.sgml, some places also need to be updated, I think.
see text ON CONFLICT UPDATE in there.