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Re: idle in txn query cancellation

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: idle in txn query cancellation
Date: 2010-02-15 08:47:09
Message-ID: 1266223629.7341.9527.camel@ebony (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
On Sat, 2010-02-13 at 22:37 +0100, Andres Freund wrote:
> On a related note I would also like to get rid of the restriction that
> a normal query cancellation will only be done if no subtransactions
> are stacked. 
> But I guess its too late for that? (I have a patch ready, some cleanup
> would be needed)
> The latter works by:
> - adding a explicit error code (which should be done regardless of
> this 
> discussion)
> - avoiding to catch such error at a few places (plperl, plpython)
> - recursively aborting the subtransactions once the mainloop is
> reached
> - relying on the fact that the cancellation signal will get resent
> - possibly escalating to a FATAL if nothing happens after a certain
> number of tries

Such an action needs to have a good, clear theoretical explanation with
it to show that the interaction with savepoints is a good one.

I toyed with the idea of a new level between ERROR and FATAL to allow
ERRORs to be handled by savepoints still in all cases.

 Simon Riggs 

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