Re: Possible solution for LIKE optimization

Peter Eisentraut <peter_e@gmx.net> writes:
> Hiroshi Inoue writes:
>> I'm not familiar with non_ASCII locale.
>> Is 'ss'  always guaranteed to be LIKE 's%'  for example ?

> Yes.  LIKE doesn't use any collation rules, since it doesn't do any
> collating.

On the other hand, LIKE *is* multibyte aware.  So the hypothetical
non-locale-aware comparison operators would need to be aware of
multibyte character sets even though not aware of locale.  And the
"add one" operator that we postulated for the LIKE index optimization
needs to be able to increment a multibyte character.

This seems doable, but the sort order of such a comparison function
might not be very pleasant, depending on what character set you are
using.
        regards, tom lane