Marko Tiikkaja <marko.tiikkaja@cs.helsinki.fi> writes:
> I traced this down to heapam.c, which has this:
> ...
> This doesn't exactly work anymore since we modify the snapshot after
> calling ExecInitScan().
So don't do that. The executor is generally entitled to assume that
parameters given to ExecutorStart are correct. In particular, changing
the snapshot after the query has started to run seems to me to ensure
all sorts of inconsistent and undesirable behavior.
regards, tom lane