Re: Leader backend hang on IPC/ParallelFinish when LWLock held at parallel query start - Mailing list pgsql-bugs

From Tom Lane
Subject Re: Leader backend hang on IPC/ParallelFinish when LWLock held at parallel query start
Date
Msg-id 1748003.1726638331@sss.pgh.pa.us
Whole thread Raw
In response to Re: Leader backend hang on IPC/ParallelFinish when LWLock held at parallel query start  (Noah Misch <noah@leadboat.com>)
List pgsql-bugs
Noah Misch <noah@leadboat.com> writes:
> What if we just ignored the plancache when uninterruptible?  The new planner
> check would then suffice.

Only if you believe that parallel-query is the only problem,
which is something I seriously doubt.  I fear that the
committed patch is just a band-aid over one symptom of the
general problem that we can't permit arbitrary operations
to be invoked from a btree comparison function.  It's late
here so I'm not sufficiently awake to think of examples,
but I'm sure there are some.

However ... clearly a maliciously-coded btree support function can
do arbitrarily bad stuff.  We restrict creation of opclasses to
superusers for exactly that reason.  If our ambitions are only
to prevent support functions from *accidentally* causing problems,
is disabling parallel query enough?  I'm still pretty uncomfortable
about it, but it's less obviously insufficient than in the general
case.

            regards, tom lane



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