Re: "cancelling statement due to user request error" occurs but the transaction has committed. - Mailing list pgsql-hackers

From Tom Lane
Subject Re: "cancelling statement due to user request error" occurs but the transaction has committed.
Date
Msg-id 29440.1402409921@sss.pgh.pa.us
Whole thread Raw
In response to Re: "cancelling statement due to user request error" occurs but the transaction has committed.  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: "cancelling statement due to user request error" occurs but the transaction has committed.  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> I don't agree with this analysis.  If the connection is closed after
> the client sends a COMMIT and before it gets a response, then the
> client must indeed be smart enough to figure out whether or not the
> commit happened.  But if the server sends a response, the client
> should be able to rely on that response being correct.  In this case,
> an ERROR is getting sent but the transaction is getting committed;
> yuck.  I'm not sure whether the fix is right, but this definitely
> seems like a bug.

In general, the only way to avoid that sort of behavior for a post-commit
error would be to PANIC ... and even then, the transaction got committed,
which might not be the expectation of a client that got an error message,
even if it said PANIC.  So this whole area is a minefield, and the only
attractive thing we can do is to try to reduce the number of errors that
can get thrown post-commit.  We already, for example, do not treat
post-commit file unlink failures as ERROR, though we surely would prefer
to do that.

So from this standpoint, redefining SIGINT as not throwing an error when
we're in post-commit seems like a good idea.  I'm not endorsing any
details of the patch here, but the 20000-foot view seems generally sound.
        regards, tom lane



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