On Tue, Apr 28, 2015 at 08:00:24PM +0000, Nicholson, Brad (Toronto, ON, CA)
wrote:
> Hi,
>
> I noticed an inaccuracy in the transaction isolation docs. Under the
> Repeatable Read Isolation Level section it states:
>
> “The Repeatable Read isolation level only sees data committed before the
> transaction began; it never sees either uncommitted data or changes committed
> during transaction execution by concurrent transactions.”
>
> That is not entirely accurate. The snapshot starts with the first SQL
> statement in the transaction, not at the start of the transaction. Any
> change that is committed in another transaction after the start of the
> transaction but before the first SQL statement will be seen.
Yes, we have fixed that for PG 9.5:
http://www.postgresql.org/docs/devel/static/transaction-iso.html
This level is different from Read Committed in that a query in a
--> repeatable read transaction sees a snapshot as of the start of the first
--> non-transaction-control statement in the transaction, not as of the
start of the current statement within the transaction. Thus, successive
SELECT commands within a single transaction see the same data, i.e.,
they do not see changes made by other transactions that committed after
their own transaction started.
--
Bruce Momjian <[email protected]> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
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