gianm commented on PR #16153:
URL: https://github.com/apache/druid/pull/16153#issuecomment-2046220895
Just looked more deeply, I think there's a bug in the logic around the
greediness of the matching. This test fails on the patch but passes on master:
```
assertMatch("%ba_", "foo bar baz", DruidPredicateMatch.TRUE);
```
The `%ba` matches `foo ba`, then the `_` matches `r`, then because there's
some string left over the overall match fails.
Making the first `%ba` greedy wouldn't be a good fit, because then this test
(which passes on the branch now) would probably start to fail:
```
assertMatch("%ba_____", "foo bar baz", DruidPredicateMatch.TRUE);
```
It seems like some kind of backtracking is necessary, like trying the
minimal-length match for `%ba` first, and then if the overall match fails,
trying a longer match.
@twilliamson what do you think about mitigating the original issue by
sticking with `java.util.Pattern`, but using your logic for pattern
normalization to simplify the regexps? Or, alternatively, enhancing the
hand-rolled logic in your patch to have some backtracking? That would surely
help for some patterns, like `%%%%x`. Although, I'm not sure if it will open
the door back up for "catastrophe". I haven't thought about the problem enough
to have a sense of that.
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