Peter Eisentraut <pete...@gmx.net> writes:
> On fre, 2011-09-23 at 20:35 +0300, Marcin MaÅk wrote:
>> One idea:
>> col like 'foo%' could be translated to col >= 'foo' and col <= foo || 'zzz'
>> , where 'z' is the largest possible character. This should be good enough
>> for calculating stats.
>> How to find such a character, i do not know.
> That's what makes this so difficult.
> If we knew the largest character, we could probably also find the
> largest-1, largest-2, etc. characters and determine the total order of
> everything.
No, it's a hundred times worse than that, because in collations other
than C there typically *is* no total order. The collation behavior of
many characters is context-sensitive, thanks to the multi-pass behavior
of typical "dictionary" algorithms.
regards, tom lane
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
