Teodor Sigaev <teodor@sigaev.ru> writes:
>> * There is a bigger race condition, which is that after a scan has
>> returned a tuple from a pending page, vacuum could move the index entry
>> into the main index structure, and then that same scan could return that
>> same index entry a second time. This is a no-no, and I don't see any easy
>> fix.
> Hmm, isn't it allowed for indexes? At least GiST has this behaviour from its
> birth date.
Really? Then GiST needs to be fixed too. Otherwise you risk having
queries return the same row twice. A bitmap indexscan plan would mask
such an index bug ... but a plain indexscan won't.
regards, tom lane