On 08/18/2012 05:19 PM, Nicolas Barbier wrote:
2012/8/7 Kevin Grittner <kevin.gritt...@wicourts.gov>:
I also think it's a problem that one can get through the entire
"Concurrency Control" chapter (mvcc.sgml) without a clue that
sequences aren't transactional.
It is possible to say that they *are* transactional when considering
the following definition: nextval() doesn’t always give you “the” next
value, but “some” next value that is higher than the one gotten by any
preceding transactions.
I personally like it better to introduce this minor complexity in the
definition of sequences, rather than messing with the definition of
transactionality.
I guess they're semi-transactional. You don't get dirty reads unless you
actually `SELECT ... FROM some_transaction` which isn't really official
API. OTOH, one transaction affects another, and they aren't subject to
rollbacks.
--
Craig Ringer
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