nmueller@cs.wisc.edu writes:
> Aug 7 13:23:30 calchas postgres[27794]: [3] ERROR: simple_heap_update:
> tuple concurrently updated
The only case of this I'm aware of is the concurrent-ANALYZE issue,
which is pretty harmless. But you say it's not that. I'd suggest
turning on log_statement and log_duration so that you can determine
(a) what query is reporting this failure and (b) what was running
concurrently with it. When you have that info for a few occurrences,
send it along and we'll try to figure out what's happening.
regards, tom lane