Re: Segfault on exclusion constraint violation

Heikki Linnakangas <hlinnakangas@vmware.com> writes:
> 9.4 and master segfaults, if an insertion would need to wait for another
> transaction to finish because of an exclusion constraint. To reproduce:
> ...
> This only happens with assertions enabled. The culprit is commit
> f88d4cfc9d417dac2ee41a8f5e593898e56fd2bd, which added the 'ctid'
> argument to XactLockTableWait. check_exclusion_constraint calls
> index_endscan() just before XactLockTableWait, but that free's the
> memory the ctid points to.

> I'll write up a patch to change those call sites to use local variables.
> Hopefully it's trivial enough to still include in 9.4.1, although time
> is really running out..

If the only known bad consequence requires assertions enabled, I think
it would be more prudent to *not* try to fix this in haste.

            regards, tom lane