Re: automatic restore point

On 02/10/2018 00:06, Alvaro Herrera wrote:
> Re-reading the implementation in standard_ProcessUtility, I wonder what
> is PROCESS_UTILITY_QUERY_NONATOMIC -- there seems to be a maze through
> SPI that determines whether this flag is set or not, which could affect
> whether the event trigger is useful. Are utilities executed through a
> procedure detected by event triggers? If so, then this mechanism seems
> good enough to me. But if there's a way to sneak utility commands (DROP
> TABLE) without the event trigger being invoked, then no (and in that
> case maybe it's just a bug in procedures and we can still not include
> this patch).

It looked for a moment that

isCompleteQuery = (context <= PROCESS_UTILITY_QUERY)

in ProcessUtilitySlow() might be a problem, since that omits
PROCESS_UTILITY_QUERY_NONATOMIC, but it's not actually a problem, since
the commands that run this way (CALL and SET from PL/pgSQL) don't have
event triggers. But anyway, I propose the attached patch to rephrase
that. Also some tests that show it all works as expected.

> On the TRUNCATE case it's a bit annoying that you can't do it with event
> triggers -- you have to create individual regular triggers on truncate
> for each table (so you probably need yet another event trigger that
> creates such triggers).

I don't see why we couldn't add event triggers on TRUNCATE or other
commands such as DELETE.

--
Peter Eisentraut http://www.2ndQuadrant.com/
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