Re: [PATCHES] Proposed patch for sequence-renaming problems

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Tom Lane wrote:
> >> Ripping out ALTER SCHEMA RENAME is not a solution unless you have a path
> >> to a solution later with more work.
>
> > Well, we are only giving ourselves a few weeks to solve this, and I
> > think a hack to make it work cleanly for users is better than supporting
> > two function names perpetually.
>
> Well, if you are dead set on having only one function name, then I think
> the best solution is this:
>
> * only one function, taking regclass
>
> * add an implicit text-to-regclass coercion
>
> With this, nextval('foo') is early binding and nextval('foo'::text) is
> late binding, and existing dumps are going to continue to behave as late
> binding unless changed manually.
>
> The implicit coercion is a bit risky, but in practice these are likely
> to be the only functions in the system that are declared to take
> regclass, so the odds of the implicit coercion firing unexpectedly seem
> low.
>
> Does that sound like a workable compromise?

Personally, I _love_ it. I hope others do as well. :-)

Let me explain why I thought two function names would be confusing. We
have been telling people to use nextval() since we added sequences in
6.4, and since 99% of people would want early binding (with
dependencies), I think making them all move to a new function name would
be a long-running education effort. If it can be avoided, that is
better.

I think the solution you propose is great because:

o it fixes SERIAL dependency
o it allows old dumps to load with no change in behavior
o it allows new nextval() calls to have early binding, unless
::text is used

In fact, the use of ::text is dump is the only thing that is _allowing_
this migration idea to work.

I think I can easily explain this issue in the release notes, and show
how users can update their schemas to the new behavior.

--
Bruce Momjian | http://candle.pha.pa.us
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