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* How to cleanup transaction after statement_timeout aborts a query?
@ 2024-09-08 10:56 Istvan Soos <[email protected]>
0 siblings, 1 reply; 2+ messages in thread
From: Istvan Soos @ 2024-09-08 10:56 UTC (permalink / raw)
To: [email protected]
I'm one of the developers of the Dart-language Postgresql client
package. I am working on adding a feature that may set the
statement_timeout value before a session or a query as the client
requests it, however, I'm stuck with the following error:
setup:
CREATE TABLE t (id INT PRIMARY KEY);
INSERT INTO t (id) values (1);
client-1:
BEGIN;
SELECT * FROM t WHERE id=1 FOR UPDATE;
<client sleeps for a while>
client-2:
BEGIN;
SET statement_timeout TO 1000;
SELECT * FROM t WHERE id=1 FOR UPDATE;
<server sends error message with the timeout>
After that any query I send through client-2 will get me the following error:
Severity.error 25P02: current transaction is aborted, commands ignored
until end of transaction block
Not even ROLLBACK or COMMIT is working. It is the same for both simple
and extended query protocol. Does the client need to send a non-query
message to cleanup the transaction state? Or is this connection now
gone for good?
Thanks,
Istvan
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: How to cleanup transaction after statement_timeout aborts a query?
@ 2024-09-08 11:18 Laurenz Albe <[email protected]>
parent: Istvan Soos <[email protected]>
0 siblings, 0 replies; 2+ messages in thread
From: Laurenz Albe @ 2024-09-08 11:18 UTC (permalink / raw)
To: Istvan Soos <[email protected]>; [email protected]
On Sun, 2024-09-08 at 12:56 +0200, Istvan Soos wrote:
> I'm one of the developers of the Dart-language Postgresql client
> package. I am working on adding a feature that may set the
> statement_timeout value before a session or a query as the client
> requests it, however, I'm stuck with the following error:
>
> setup:
> CREATE TABLE t (id INT PRIMARY KEY);
> INSERT INTO t (id) values (1);
>
> client-1:
> BEGIN;
> SELECT * FROM t WHERE id=1 FOR UPDATE;
> <client sleeps for a while>
>
> client-2:
> BEGIN;
> SET statement_timeout TO 1000;
> SELECT * FROM t WHERE id=1 FOR UPDATE;
> <server sends error message with the timeout>
>
> After that any query I send through client-2 will get me the following error:
>
> Severity.error 25P02: current transaction is aborted, commands ignored
> until end of transaction block
>
> Not even ROLLBACK or COMMIT is working. It is the same for both simple
> and extended query protocol. Does the client need to send a non-query
> message to clean up the transaction state? Or is this connection now
> gone for good?
ROLLBACK and COMMIT are working: they end the transaction.
It is the atomicity guarantee of database transactions: either all statements
succeed, or all fail.
I am aware that other databases have a "statement rollback" feature that allows
the transaction to proceed after an error, but PostgreSQL doesn't.
To handle the failure of a statement while allowing the transaction to proceed,
you can use savepoints. But be warned: don't even think of setting a savepoint
before each statement. That would affect statement performance severely.
Yours,
Laurenz Albe
^ permalink raw reply [nested|flat] 2+ messages in thread
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