Re: Progress report on locale safe LIKE indexing

Peter Eisentraut wrote:
>
> Hiroshi Inoue writes:
>
> > Hmm * string1 = string2 * doesn't imply * string1 LIKE string2 * ?
>
> In the current implementation of LIKE, you're right. The SQL standard
> allows for the possibility that "[d]epending on the collating sequence,
> two strings may compare as equal even if they are of different lengths or
> contain different sequences of characters." However, I doubt that this
> can really happen in practice. For example, in some collating sequences
> (such as en_US), characters with diacritic marks (accents) are "more
> equal" than others, but in the end there's always a tie breaker. Or do
> you know an example where this really happens?

I can see the examples in a documentation M$ SQL Server though
I can't try it in reality.
For example
ignore case(low/high)
ignore accents

I don't think they are strange as collating sequences.

You are establishing a pretty big mechanism and I think
you should clarify the assumption.
Please tell me the assumption.
I can think of the followings.

1) Because the current implementaion of LIKE isn't locale-aware,
we should be compatible with it for ever.
2) strcoll(str1, str2) == 0 means strcmp(str1, str2) == 0
in any locale.

regards,
Hiroshi Inoue