Re: delta relations in AFTER triggers

On Sat, May 06, 2017 at 05:33:24AM +0000, Noah Misch wrote:
> On Thu, May 04, 2017 at 09:51:03PM +1200, Thomas Munro wrote:
> > On Thu, May 4, 2017 at 9:12 PM, Prabhat Sahu
> > <prabhat.sahu@enterprisedb.com> wrote:
> > > I have been testing this for a while and observed a server crash while referencing table column value in a trigger procedure for AFTER DELETE trigger.
> > >
> > > -- Steps to reproduce:
> > > CREATE TABLE t1(c1 int);
> > > CREATE TABLE t2(cc1 int);
> > > INSERT INTO t1 VALUES (10);
> > > INSERT INTO t2 VALUES (10);
> > >
> > > CREATE OR REPLACE FUNCTION trig_func() RETURNS trigger AS
> > > $$ BEGIN
> > >     DELETE FROM t1 WHERE c1 IN (select OLD.cc1 from my_old);
> > >     RETURN OLD;
> > > END; $$ LANGUAGE PLPGSQL;
> > >
> > > CREATE TRIGGER trg1
> > >   AFTER DELETE ON t2
> > >     REFERENCING OLD TABLE AS my_old
> > >     FOR EACH ROW
> > >   EXECUTE PROCEDURE trig_func();
> > >
> > > DELETE FROM t2 WHERE cc1 =10;
> > > server closed the connection unexpectedly
> > >     This probably means the server terminated abnormally
> > >     before or while processing the request.
> > > The connection to the server was lost. Attempting reset: Failed.
> > 
> > Reproduced here.  The stack looks like this:
> > 
> >     frame #3: 0x000000010f06f8b0
> > postgres`ExceptionalCondition(conditionName="!(readptr->eflags &
> > 0x0002)", errorType="FailedAssertion", fileName="tuplestore.c",
> > lineNumber=1237) + 128 at assert.c:54
> >     frame #4: 0x000000010f0cbc85
> > postgres`tuplestore_rescan(state=0x00007ff219840200) + 85 at
> > tuplestore.c:1237
> >     frame #5: 0x000000010eced9b1
> > postgres`ExecReScanNamedTuplestoreScan(node=0x00007ff21d007840) + 81
> > at nodeNamedtuplestorescan.c:197
> >     frame #6: 0x000000010eca46a6
> > postgres`ExecReScan(node=0x00007ff21d007840) + 822 at execAmi.c:216
> >     frame #7: 0x000000010ece7eca
> > postgres`ExecNestLoop(node=0x00007ff21d006310) + 538 at
> > nodeNestloop.c:148
> > 
> > I think the problem is that the tuplestore read pointer hasn't been
> > opened with the "rewindable" flag.  It works for me with the attached.
> 
> [Action required within three days.  This is a generic notification.]
> 
> The above-described topic is currently a PostgreSQL 10 open item.  Kevin,
> since you committed the patch believed to have created it, you own this open
> item.  If some other commit is more relevant or if this does not belong as a
> v10 open item, please let us know.  Otherwise, please observe the policy on
> open item ownership[1] and send a status update within three calendar days of
> this message.  Include a date for your subsequent status update.  Testers may
> discover new open items at any time, and I want to plan to get them all fixed
> well in advance of shipping v10.  Consequently, I will appreciate your efforts
> toward speedy resolution.  Thanks.
> 
> [1] https://www.postgresql.org/message-id/20170404140717.GA2675809%40tornado.leadboat.com

This PostgreSQL 10 open item is past due for your status update.  Kindly send
a status update within 24 hours, and include a date for your subsequent status
update.  Refer to the policy on open item ownership:
https://www.postgresql.org/message-id/20170404140717.GA2675809%40tornado.leadboat.com