| From: | Noah Misch <noah(at)leadboat(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Avoiding rewrite in ALTER TABLE ALTER TYPE |
| Date: | 2010-12-31 05:47:46 |
| Message-ID: | 20101231054746.GA12460@tornado.leadboat.com |
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| Lists: | pgsql-hackers |
On Fri, Dec 31, 2010 at 12:34:50AM -0500, Robert Haas wrote:
> On Thu, Dec 30, 2010 at 8:35 PM, Noah Misch <noah(at)leadboat(dot)com> wrote:
> > 4. A FuncExpr node has answers given by the bitwise-AND of its funcexempt field
> > and the answers from its first argument.
>
> Why its first argument?
funcexempt would only be nonzero for FuncExpr of length coercion casts. Those
have the subject datum as a first argument, typmod as second, and is-explicit
boolean as third. The other arguments are effectively already validated.
That brings up a point -- the exemptor function also needs an is-explicit
argument, as that affects the decision for some types.
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