Re: WIP: generalized index constraints

2009/8/21 Brendan Jurd <direvus(at)gmail(dot)com>:
> 2009/8/21 Jeff Davis <pgsql(at)j-davis(dot)com>:
>> On Fri, 2009-08-21 at 12:23 +1000, Brendan Jurd wrote:
>>> The current behaviour seems to be predicated on the unique constraint
>>> being an integral part of the index itself.  While this might be true
>>> from a system catalog point of view (pg_index.indisunique), if a user
>>> says that they want to copy a table's structure INCLUDING INDEXES
>>> EXCLUDING CONSTRAINTS then IMO they've made their intention perfectly
>>> clear.  They'd expect it to create an index sans the unique
>>> constraint.  Ignoring the user's intention and copying the index as-is
>>> (including the unique constraint) would be unfriendly.
>>
>> I don't have strong feelings either way. I think that's probably a
>> separate patch, and a fairly small patch.
>>
>
> Yeah, as I was writing the above I was thinking that it might end up a
> separate patch.  However I was also concerned that it might be less
> disruptive if we implement your patch with the less-astonishing
> behaviour and fix the unique index case in passing, than to commit
> your patch with the bad behavior and then fix both.
>
> Up to you.
>

Hi Jeff,

Any update on this patch? The discussion appeared to trail off around
21 Aug with some inconclusive thoughts about handling the corner cases
in CREATE TABLE LIKE.

The September CF starts in a couple of days, so this patch is in
danger of missing the boat.

The unresolved points seem to be:

* What to do about INCLUDING INDEXES EXCLUDING CONSTRAINTS --
Postgres gets this wrong for unique indexes currently. Should we
persist with the existing behaviour or fix it as part of this patch?
My personal feeling was +1 for fixing it in this patch.

* Should we emit some sort of message when the user specifies
INCLUDING INDEXES or INCLUDING CONSTRAINTS but not both? I didn't
have strong feelings about this one but there was some differing
thoughts about what log level to use. I thought NOTICE but Alvaro
reckons we've got too many of those already. Tom mentioned the
suggested (but unimplemented) NOVICE level, which seems like a good
move but doesn't resolve the problem of what to do in this patch. One
option would be to add a message at the NOTICE level with a TODO to
downgrade it to NOVICE if/when that becomes available.

Cheers,
BJ