Обсуждение: Nested transactions
Does PostgreSQL support nested transactions as shown below?
BEGIN;
...do some stuff...
BEGIN;
...more stuff...
COMMIT;
COMMIT;
Bill
On Sun, Oct 11, 2009 at 8:41 PM, Bill Todd <pg@dbginc.com> wrote: > Does PostgreSQL support nested transactions as shown below? > > BEGIN; > ...do some stuff... > BEGIN; > ...more stuff... > COMMIT; > COMMIT; Postgresql uses savepoints.
Bill Todd wrote: > Does PostgreSQL support nested transactions as shown below? > > BEGIN; > ...do some stuff... > BEGIN; > ...more stuff... > COMMIT; > COMMIT; no, but in recent versiosn, you can use SAVEPOINT to achieve much the same effect. http://www.postgresql.org/docs/current/static/sql-savepoint.html
On Sun, Oct 11, 2009 at 07:41:54PM -0700, Bill Todd wrote: > Does PostgreSQL support nested transactions as shown below? > > BEGIN; > ...do some stuff... > BEGIN; > ...more stuff... > COMMIT; > COMMIT; It depends what you want to have happen when the outer transaction rolls back. If you want all the sub-commits to roll back, use SAVEPOINTs. If you don't, you'll have to write something in an untrusted PL that uses a separate database connection. Cheers, David. -- David Fetter <david@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fetter@gmail.com Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate
Scott Marlowe wrote:
Bill
Savepoints do not provide the same functionality as nested or parallel transactions because you cannot commit a savepoint. If I need a second transaction I can always open a second connection so it is easy to get the behavior I need. Thanks.On Sun, Oct 11, 2009 at 8:41 PM, Bill Todd <pg@dbginc.com> wrote:Does PostgreSQL support nested transactions as shown below? BEGIN; ...do some stuff... BEGIN; ...more stuff... COMMIT; COMMIT;Postgresql uses savepoints.
Bill
On Mon, 2009-10-12 at 16:18 -0700, Bill Todd wrote:
> Savepoints do not provide the same functionality as nested or parallel
> transactions because you cannot commit a savepoint.
What does it mean to "commit" a subtransaction or savepoint? What can
you do with a subtransaction that you can't do with a savepoint?
Regards,
Jeff Davis
Jeff Davis escribió: > On Mon, 2009-10-12 at 16:18 -0700, Bill Todd wrote: > > Savepoints do not provide the same functionality as nested or parallel > > transactions because you cannot commit a savepoint. > > What does it mean to "commit" a subtransaction or savepoint? What can > you do with a subtransaction that you can't do with a savepoint? What Bill wants is an "autonomous" transaction. We don't have those yet (except thru use of dblink or database connections inside a function.) -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support
On Mon, Oct 12, 2009 at 5:18 PM, Bill Todd <pg@dbginc.com> wrote: > Scott Marlowe wrote: > > On Sun, Oct 11, 2009 at 8:41 PM, Bill Todd <pg@dbginc.com> wrote: > > > Does PostgreSQL support nested transactions as shown below? > > BEGIN; > ...do some stuff... > BEGIN; > ...more stuff... > COMMIT; > COMMIT; > > > Postgresql uses savepoints. > > > > > Savepoints do not provide the same functionality as nested Yes they do. There was a REALLY long discussion on the subject in the hackers list I believe that led to pgsql supporting savepoints but not nested transactions > or parallel transactions That's something entirely different and a question you did not ask