>> If a transaction marks a tuple for update and later commits without

>> actually having updated the tuple, [...] can we simply
>> set the HEAP_XMAX_INVALID hint bit of the tuple?
>
>AFAICS this is a reasonable thing to do.

Thanks for the confirmation.  Here's a patch which also contains some
more noncritical changes to tqual.c:
 .  make code more readable by introducing local variables for xvac
 .  no longer two separate branches for aborted and crashed.
    The actions were the same in all cases.

Manfred Koizar