--- In firebird-support@yahoogroups.com, "Ann W. Harrison" <aharrison@...> wrote:
>
> On 1/25/2011 3:45 AM, neodreamer@... wrote:
> > I work two isql instance with one database. ((A isql instance) and (B isql intance) is connected with test.fdb.)
> >
> > A isql : Create table. (table name is "member")
> >
> > B isql : Can see the table.(SHOW SCHEMA "member") (I know that DDL is committed automatically.)
> >
> > A isql : Insert one record into the "member" table.
> >
> > B isql : Cannot find any data on "member" table.( I cannot find data because It does not commit on A isql. I think... )
> >
> > A isql : Run commit command.
> >
> > B isql : Cannot find any data on "member" table. (WHY??)
>
>
> Because one of the cardinal virtues of transactions is ISOLATION,
> the I in ACID. The changes made by concurrent transactions don't
> affect each other. When B did its first query, it started a transaction
> and will see a consistent state of the database until it commits and
> starts a new transaction which will continue to see the database in
> a consistent state until it ends. Nothing that A does during B's
> transaction will be visible. That's important if you want do do
> multi-pass operations like percent of total or median.
>
> Good luck,
>
> Ann
>