On Wed, Sep 24, 2014 at 2:01 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote:
"Steve Dodd" <steve@xxxxxxxxxxxxxxxx> writes:
> Say we have two transactions run sequentially: T1 writes some data, and T2 reads the written data. There is a non-zero time delay between the apparent T1 commit, and the subsequent T2 query.
> Is there any guarantee that the data written in T1 will be visible to the query in T2?
> We have a situation in our system where it would appear that the answer is NO.
Extremely hard to believe. There is a very well-defined point where the
transaction's effects become visible to other transactions, and that is
certainly before the commit is reported as complete to the client.
I suspect if you dig into it you'll find that your client-side code
is doing something unexpected.
Also worth checking is that "T2" is actually a transaction, and not
a single statement within a serializable-mode transaction. In the latter
case it would see the database state as of the transaction's snapshot,
which might precede T1's commit.
regards, tom lane
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