Re: Support LIKE with nondeterministic collations

On 18.11.24 04:30, jian he wrote:
> we can optimize when trailing (last character) is not wildcards.
>
> SELECT 'Ha12foo' LIKE '%foo' COLLATE ignore_accents;
> within the for loop
> for(;;)
> {
> int cmp;
> CHECK_FOR_INTERRUPTS();
> ....
> }
>
> pg_strncoll comparison will become
> Ha12foo foo
> a12foo foo
> 12foo foo
> 2foo foo
> foo foo
>
> it's safe because in MatchText we have:
> else if (*p == '%')
> {
> while (tlen > 0)
> {
> if (GETCHAR(*t, locale) == firstpat || (locale && !locale->deterministic))
> {
> int matched = MatchText(t, tlen, p, plen, locale);
> if (matched != LIKE_FALSE)
> return matched; /* TRUE or ABORT */
> }
> NextChar(t, tlen);
> }
> }
>
> please check attached.

I see, good idea. I implemented it a bit differently. See "Shortcut:
If this is the end of the pattern ..." in this patch. Please check if
this is what you had in mind.