Re: When is newly inserted data visible to another connection?

fkater(at)googlemail(dot)com wrote:
> Hi all,
>
> If there is nothing else wrong in our test case we noticed
> the following:
>
> We have done a test with two connections to the database on
> different computers. After the first client (writer) had
> inserted new data into a quite simple table, it told another
> client (by TCP communication) to be ready, however, this
> second client (reader) did not see the data then immediately
> in the database. So we delayed the reading client from 2 to
> 5s to have it see all data in the table.
>
Essential information is missing. Did the first client COMMIT before
toggling client 2? Also you might find the information from
http://developer.postgresql.org/pgdocs/postgres/transaction-iso.html
interesting, since that specifies how to control behaviour of concurrent
transactions looking at each others data.
> Secondly: If yes, is there a way to determine when newly
> inserted data is visible to other clients?
>
Not before it is committed. To which clients the just committed data is
visible depends on the transaction isolation level (see link above).

regards,
Yeb Havinga