> -----Original Message-----
> From: Tom Lane [mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us]
> Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp> writes:
> > Do we have a conclusion about this thread ?
> > If no,how about changing heap_open(r) so that they allocate
> > Relation descriptors after acquiring a lock on the table ?
> > We would use LockRelation() no longer.
> That won't do by itself,
Doesn't current heap_open() have a flaw that even the first
use of a relation in a transaction may cause an error
"relation ### modified while in use" ?
> because that will open us up to failures when
> a relcache invalidation arrives mid-transaction and we don't happen to
> have the relation open at the time. We could still have parse/plan
> results that depend on the old relation definition.
PL/pgSQL already prepares a plan at the first execution
time and executes the plan repeatedly after that.
We would have general PREPARE/EXECUTE feature in the
near fututre. IMHO another mechanism to detect plan invali
dation is needed.
BTW,I sometimes see
ERROR: SearchSysCache: recursive use of cache 10(16)
under small MAXNUMMESSAGES environment.
I'm not sure about the cause but suspicious if sufficiently
many system relations are nailed for "cache state reset".
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