Re: UPSERT wiki page, and SQL MERGE syntax

On 10/12/14, 2:36 PM, Matthew Woodcraft wrote:
> On 2014-10-10 19:44, Kevin Grittner wrote:
>> To restate: to do so is conflating the logical definition of the
>> database with a particular implementation detail.  As just one
>> reason that is a bad idea: we can look up unique indexes on the
>> specified columns, but if we implement a other storage techniques
>> where there is no such thing as a unique index on the columns, yet
>> manage to duplicate the semantics (yes, stranger things have
>> happened), people can't migrate to the new structure without
>> rewriting their queries
>
> Wouldn't it be good enough to define the 'WITHIN' as expecting a
> unique-constraint name rather than an index name (even though those
> happen to be the same strings)?
>
> I think constraints are part of the logical definition of the database,
> and a new storage technique which doesn't use indexes should still have
> names for its unique constraints.

What about partial indexes?  Indexes on expressions or functions calls?


.marko