zhuliquan opened a new pull request, #13235:
URL: https://github.com/apache/datafusion/pull/13235
## Which issue does this PR close?
## Rationale for this change
I notice that some expressions are semantically equivalent. (i.g. `a + b`
and `b + a` is equivalent). I think their expressions can be optimized in CSE
(i.e. common subexper eliminate) process. For example: we can optimize below
logical plan.
before:
```text
Filter: (test.a + test.b) * (test.b + test.a) = Int32(30)
TableScan: test
```
after:
```text
Projection: test.a, test.b, test.c
Filter: __common_expr_1 * __common_expr_1 = Int32(30)
Projection: test.a + test.b AS __common_expr_1, test.a, test.b, test.c
TableScan: test
```
In example, we extract common expr `test.a + test.b`, as `test.a + test.b`
is equal to `test.b + test.a` semantically.
## What changes are included in this PR?
1. adding code of normalizing node before CSE in function
`extract_common_nodes`.
2. adding trait `NormalizeNode` and implement this trait for enum `Expr`.
3. adding some normalize rule for some specific `BinaryExpr` (including
`Plus` / `Multi` / `BitsetAnd` / `BitsetOr` / `BitsetXor` / `Gt` / `GtEq` /
`Eq` / `NotEq` expressions)
## Are these changes tested?
yes, I add below test cases.
1. test_normalize_add_expression
2. test_normalize_multi_expression
4. test_normalize_bitset_and_expression
5. test_normalize_bitset_or_expression
6. test_normalize_bitset_xor_expression
7. test_normalize_gt_expression
8. test_normalize_gte_expression
9. test_normalize_eq_expression
10. test_normalize_ne_expression
## Are there any user-facing changes?
No
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