With this commit, SQL functions LIKE and MATCH and their variants can
work with non-const needle arguments. E.g.
create table tab
(id UInt32, haystack String, needle String)
engine = MergeTree()
order by id;
insert into tab values
(1, 'Hello', '%ell%')
(2, 'World', '%orl%')
select id, haystack, needle, like(haystack, needle)
from tab;
For that, methods vectorVector() and vectorFixedVector() were added to
MatchImpl. The existing code for const needles has an optimization where
the compiled regexp is cached. The new code expects a different needle
per row and consequently does not cache the regexp.
The previous logic was smart but too inflexible to support the next
commits. Replace by a simple pushdown logic where string search
implementations return their const arguments instead of having the
common class figure these out based on properties/traits.
