As a follow up, I've selected max(common_key) from the table and setval()'ed on the sequence to that +1 and I think that should make this go away. Any reason why that's insane?
Ah, I think that must be it-- there are 200 some rows where manually supplied values for that common_key column are higher than the nextval() on the serial. So eventually they might be "re-used".
I have a simple table with a given column defined like so:
common_key| integer | | not null | nextval('alias.identity_common_key_seq'::regclass)| plain
Very very very infrequently, on an INSERT where this column is not specified, this column will be assigned a value that already exists in the table, versus the next presumably unused value in the sequence. I cannot figure this out. Is there any reason why this might be the case?
Most likely someone inserted data without using the sequence and eventually the sequence catches up with that previously inserted data.
