Thread: Documentation should state what happens, when a commit fails
The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/17/sql-commit.html Description: Deferrable constraints, deadlocks and possibly other deferred or lazily evaluated rules are checked upon commit. What happens if they are not met and the commit statement fails? Does the transaction then implicitly rollback? Or do I need an explicit rollback?
On Wed, 2025-05-28 at 08:08 +0000, PG Doc comments form wrote: > The following documentation comment has been logged on the website: > > Page: https://www.postgresql.org/docs/17/sql-commit.html > Description: > > Deferrable constraints, deadlocks and possibly other deferred or lazily > evaluated rules are checked upon commit. > What happens if they are not met and the commit statement fails? Does the > transaction then implicitly rollback? Or do I need an explicit rollback? I think it would be good to mention that a failed COMMIT automatically performs a ROLLBACK. Do you want to suggest a patch? Yours, Laurenz Albe
On Wed, 2025-05-28 at 08:08 +0000, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
>
> Page: https://www.postgresql.org/docs/17/sql-commit.html
> Description:
>
> Deferrable constraints, deadlocks and possibly other deferred or lazily
> evaluated rules are checked upon commit.
> What happens if they are not met and the commit statement fails? Does the
> transaction then implicitly rollback? Or do I need an explicit rollback?
I think it would be good to mention that a failed COMMIT automatically
performs a ROLLBACK. Do you want to suggest a patch?
Wow, great improvement, thanks!
The "tutorial-transactions" opens a new question that might be useful to know: when a transaction enters the aborted state at an early point in time (as has now become clear), does this mean it will also relinquish any locks and predicate locks early, or will it still hold onto those until explicitly rolled back by command?
_Mark
From: David G. Johnston <david.g.johnston@gmail.com>
Sent: Wednesday, May 28, 2025 at 4:04 PM UTC+2
To: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: mark@makr.zone <mark@makr.zone>, pgsql-docs@lists.postgresql.org <pgsql-docs@lists.postgresql.org>
Subject: RE: Documentation should state what happens, when a commit fails
On Wednesday, May 28, 2025, Laurenz Albe <laurenz.albe@cybertec.at> wrote:On Wed, 2025-05-28 at 08:08 +0000, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
>
> Page: https://www.postgresql.org/docs/17/sql-commit.html
> Description:
>
> Deferrable constraints, deadlocks and possibly other deferred or lazily
> evaluated rules are checked upon commit.
> What happens if they are not met and the commit statement fails? Does the
> transaction then implicitly rollback? Or do I need an explicit rollback?
I think it would be good to mention that a failed COMMIT automatically
performs a ROLLBACK. Do you want to suggest a patch?Feel free to review mine for this topic and suggest additions.David J.
Wow, great improvement, thanks!
The "tutorial-transactions" opens a new question that might be useful to know: when a transaction enters the aborted state at an early point in time (as has now become clear), does this mean it will also relinquish any locks and predicate locks early, or will it still hold onto those until explicitly rolled back by command?
On Wed, May 28, 2025 at 7:47 AM mark maker <mark@makr.zone> wrote:Wow, great improvement, thanks!
The "tutorial-transactions" opens a new question that might be useful to know: when a transaction enters the aborted state at an early point in time (as has now become clear), does this mean it will also relinquish any locks and predicate locks early, or will it still hold onto those until explicitly rolled back by command?
I suppose if the system knows there are no savepoints in progress it could release the locks and whatnot...not sure if it knows that and acts upon that knowledge if it does. Easy enough to test with two psql sessions if you want to give it a go before I or someone else gets around to it.
On Wed, 2025-05-28 at 11:09 -0400, Dave Cramer wrote: > Somewhat annoying feature of this behaviour is that when COMMIT is issued on an aborted transaction no error is reported. > Most drivers work around this problem by keeping track of the previous error and reporting an error on the COMMIT. We have been there before: https://postgr.es/m/b9fb50dc-0f6e-15fb-6555-8ddb86f4aa71%40postgresfriends.org Nothing came of that discussion though. Yours, Laurenz Albe