Re: RelationFlushRelation() or RelationClearRelation()

On 06 Nov 2001 at 14:54 (-0500), Tom Lane wrote:
| Brent Verner <brent@rcfile.org> writes:
| >   I've almost got the ALTER TABLE RENAME fixed so it doesn't break
| > triggers referring to the renamed column.  The final problem is that
| > after the pg_trigger.tgargs is updated, that change is not visible 
| > in the current backend.
| 
| This should happen automatically as a consequence of the relcache flush
| message.  Doing a manual RelationClearRelation or whatever is NOT the
| answer; if you find yourself doing that, it means that other backends
| aren't hearing about the change either.

gotcha. I don't know what you mean by 'relcache flush message,' but
I'll figure that out soon ;-)

| The usual way to force a relcache flush is to update the relation's
| pg_class row.  Now that I think about it, I'm not sure ALTER TABLE
| RENAME COLUMN would have any direct reason to do that, so it may be
| broken already in this regard.  Does the relcache entry's column
| data get updated with the new name?

The relation->triggerdesc still has the old tgargs after updating the
pg_trigger table, so the triggered RI_ function is called with the
old arguments.

It is probably noteworthy that I am directly modifying the tgargs
in the pg_trigger table, via simple_heap_update().  This modfication
is made at the end of renameatt() in rename.c.  Could making this
change prior to the column rename cause the 'relcache flush message' 
to do the right thing?  [I'm going to try this as soon as I'm off work.]

Also, is directly updating the pg_trigger table advisable?  I'll
look further at trigger.c to see if I overlooked any utility to do
this cleaner.

cheers. brent

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