kumarUjjawal opened a new pull request, #22361:
URL: https://github.com/apache/datafusion/pull/22361
## Which issue does this PR close?
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- Closes #22185.
## Rationale for this change
Pathological literal regexes in `regexp_like` can spend a long time in
planning.
Today the simplifier can constant-fold `regexp_like` with literal arguments,
or fold the lowered regex operator on a later pass. Both paths compile the
user-provided regex during planning. For patterns like
`a{5}{5}{5}{5}{5}{5}{5}{5}`, that can walk the regex crate's `size_limit` and
burn planner CPU before any data is touched.
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## What changes are included in this PR?
- add `ScalarUDFImpl::should_const_evaluate()` so scalar UDFs can opt out
of constant folding
- make `regexp_like` opt out of constant folding
- make `ConstEvaluator` skip regex match binary operators
- add a regression test that plans a pathological `regexp_like` query and
checks the expression is preserved
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## Are these changes tested?
Yes
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## Are there any user-facing changes?
No api change
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