Hi hackers,
The SLRU managed by predicate.c can wrap around and overwrite data if
you have more than 1 billion active XIDs. That's because when SSI was
implemented, slru.c was limited to four digit segment names, which
implied a page limit that wasn't enough for pg_serial to have space
for every possible XID. We should probably rip that code out, because
SLRUs now support five digit segment names. Something like the
attached. I'll post a test script to demonstrate correct wraparound
behaviour around in time for one of the later CFs.
--
Thomas Munro
http://www.enterprisedb.com