Re: RangeVarGetRelid()

Robert Haas <robertmhaas@gmail.com>

From: Robert Haas <robertmhaas@gmail.com>

To: Noah Misch <noah@leadboat.com>

Cc: Alvaro Herrera <alvherre@commandprompt.com>, Pg Hackers <pgsql-hackers@postgresql.org>

Date: 2011-12-16T00:04:20Z

Lists: pgsql-hackers

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Try to acquire relation locks in RangeVarGetRelid.
- 4240e429d0c2 9.2.0 cited

On Fri, Dec 9, 2011 at 5:41 PM, Noah Misch <noah@leadboat.com> wrote:
> It also seems my last explanation didn't convey the point.  Yes, nearly every
> command has a different set of permissions checks.  However, we don't benefit
> equally from performing each of those checks before acquiring a lock.
> Consider renameatt(), which checks three things: you must own the relation,
> the relation must be of a supported relkind, and the relation must not be a
> typed table.  To limit opportunities for denial of service, let's definitely
> perform the ownership check before taking a lock.  The other two checks can
> wait until we hold that lock.  The benefit of checking them early is to avoid
> making a careless relation owner wait for a lock before discovering the
> invalidity of his command.  That's nice as far as it goes, but let's not
> proliferate callbacks for such a third-order benefit.

I agree, but my point is that so far we have no callbacks that differ
only in that detail.  I accept that we'd probably want to avoid that.

-- 
Robert Haas
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