Il 30/08/2012 4.01, Craig Ringer ha scritto:
> On 08/28/2012 10:46 PM, Nicola Cisternino wrote:
>
>> 1) Why PostgreSQL don't use COLLATE to manage case sensitive /
>> insensitive comparision (I think it's the best and ANSI standard way
>> ....) ?
>
> Support for per-column collations in PG was only added relatively
> recently - in 9.1, by the looks:
>
> http://www.postgresql.org/docs/9.1/static/collation.html
>
> Prior to that, there was no meaningful way to use case insensitive
> collations, as these would affect the whole database, including system
> tables, which could break all sorts of things in new and exciting ways.
>
> With the advent of per-column and per-operation collation control,
> case-insensitive collations become very appealing.
>
> One of the challenges with adding case insensitive collations is that,
> AFAIK, collations are implemented using the operating system charset
> and locale support, which may not offer case insensitive collation
> directly.
>
> Another challenge is the rather ... variable ... meaning of "case
> insensitive". Results are likely to vary between host platforms and
> versions.
>
> Still, now that per-col / per-op collation is supported, it'd be nice
> to have. I don't know if it's just a matter of needing someone with
> the desire and time (or funding) and expertise to design and build it,
> or if there'd be issues with getting it accepted.
>
> --
> Craig Ringer
>
Thus the problem is that " .... collations are implemented using the
operating system charset and locale support ... " while, other engines,
implements collations internally ..... is it right ?
Thanks.