The tuple toaster currently fetches toast-table rows using SnapshotAny.
This is quite uncool, because it will in fact find *any* row. Including
dead rows resulting from an aborted (or, in 7.2, still-in-progress)
VACUUM.
I believe this is the explanation for a problem report I'm currently
chasing from Joshua Drake:
digivision2=# select * from change_log;
ERROR: chunk 1 for toast value 3388774 appears multiple times
(there are some thousands of rows with similar problems)
I suggest SnapshotSelf instead. Comments anyone?
regards, tom lane