Hmm, we're not out of the woods yet: thorntail is even less happy
than before.
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=thorntail&dt=2020-10-23%2018%3A08%3A11
I do not have 64-bit big-endian hardware to play with unfortunately.
But what I suspect is happening here is less about endianness and
more about alignment pickiness; or maybe we were unlucky enough to
index off the end of the shmem segment. I see that verify_heapam
does this for non-redirect tuples:
/* Set up context information about this next tuple */
ctx.lp_len = ItemIdGetLength(ctx.itemid);
ctx.tuphdr = (HeapTupleHeader) PageGetItem(ctx.page, ctx.itemid);
ctx.natts = HeapTupleHeaderGetNatts(ctx.tuphdr);
with absolutely no thought for the possibility that lp_off is out of
range or not maxaligned. The checks for a sane lp_len seem to have
gone missing as well.
regards, tom lane