Re: SQL/JSON: JSON_TABLE - pg_stat_statements crash

út 14. 9. 2021 v 20:04 odesílatel Erik Rijkers <er(at)xs4all(dot)nl> napsal:

> On 9/14/21 2:53 PM, Andrew Dunstan wrote:
> > On 9/13/21 5:41 AM, Erik Rijkers wrote:
> >> On 9/2/21 8:52 PM, Andrew Dunstan wrote:
> >>
>
> >> [0001-SQL-JSON-functions-v51.patch]
> >> [0002-JSON_TABLE-v51.patch]
> >> [0003-JSON_TABLE-PLAN-DEFAULT-clause-v51.patch]
> >> [0004-JSON_TABLE-PLAN-clause-v51.patch]
>
> Thanks, builds fine now.
>
> But I found that the server crashes on certain forms of SQL when
> postgresql.conf has a 'shared_preload_libraries' that contains module
> 'pg_stat_statements' (my value was:
> 'pg_stat_statements,auth_delay,auto_explain,passwordcheck'). Only
> pg_stat_statements seems to cause the problem.
>
> The offending SQL (I took it from the jsonb_sqljson.sql test file):
>
> testdb=# SELECT JSON_EXISTS(jsonb '{"a": 1, "b": 2}', '$.* ? (@ > $x &&
> @ < $y)' PASSING 0 AS x, 2 AS y);
> 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.
> Time: 2.551 ms
> !?>
>
> (Of course, that SQL running during regression testing has no problems
> as there is then no pg_stat_statements.)
>
> The statement sometimes succeeds but never very often.
>
> The same crash was there before but I only now saw the connection with
> the 'shared_preload_libraries/pg_stat_statements'.
>
> I seem to remember some things changed in pg_stat_statements but I
> didn't follow and don't know who to CC for it.
>

These issues are easily debugged - you can run gdb in the outer terminal,
and attach it to the psql session. Then you can run the query.

Probably it will be a problem in pg_stat_statements callbacks - maybe query
processing there doesn't know some new nodes that this patch introduces.

Regards

Pavel

> Thanks,
>
> Erik Rijkers
>