yujun777 commented on PR #69921:
URL: https://github.com/apache/doris/pull/69921#issuecomment-6573881958
Could we update the duplicate-candidate handling together with the relaxed
independence check?
`getCandidates()` still calls `candidates.clear()` and breaks when it sees
another candidate for the same expression. The relaxation makes this reachable
for shared-slot candidates and can discard useful candidates for unrelated
slots as well.
For example, consider the expression passed to `rewriteTree(Expression)`:
```sql
(
b = 10
AND a = 1
AND ((a = 1 AND c = 100) OR (a = 2 AND c = 200))
)
OR (b = 20 AND a = 3)
```
The bottom-up rewrite of the inner OR adds `a IN (1, 2)` alongside the
retained inner OR. In the first outer disjunct, candidate collection then sees
`b = 10`, `a = 1`, and `a IN (1, 2)`. Both `a` candidates now pass the relaxed
check, but the second one clears the entire map, including `b`. With the
previous independence check, the shared `a` candidates were skipped and `b IN
(10, 20)` could still be inferred at the outer level.
Within a conjunction, compatible constraints on the same slot should be
combined by intersection: `a = 1 AND a IN (1, 2)` gives `a = 1`. Across
disjuncts, their candidate values are combined by union. Please preserve the
existing type/NULL semantics, especially when an intersection is empty, and
avoid discarding candidates for other slots. A test through
`rewriteTree(Expression)`, the entry point used by `InferInPredicateFromOr`,
would cover this nested shape. This is a rule-level inference regression; I
have not established an end-to-end query slowdown or a wrong-result case.
**Non-blocking suggestion:** I would prefer removing
`enable_or_to_in_shared_slot_inference`. This rewrite does not introduce a
user-selectable semantic behavior, and adding a permanent FE config solely as a
safeguard against possible implementation bugs adds configuration and
maintenance complexity. The rule's guards and tests should establish
correctness. Removing the config is a suggestion, not a requirement for
merging; the duplicate-candidate handling above is a separate concern.
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