morrySnow opened a new pull request, #64718:
URL: https://github.com/apache/doris/pull/64718
## Problem
The USING JOIN merge key selection was always using the left-side USING
column as the output key, which leads to bugs:
| Issue | Join Type | Bug Behavior |
|-------|-----------|-------------|
| **DORIS-25927** | RIGHT/FULL OUTER JOIN | Right-only rows output NULL for
the merge key (left side is NULL) |
| **DORIS-26080** | RIGHT/OUTER JOIN | Merge key incorrectly selected from
wrong side |
| **DORIS-26085** | RIGHT SEMI JOIN | Merge key dropped from output entirely
|
## Root Cause
In `BindExpression.bindUsingJoin()`, the `exceptAsteriskOutputs` was always
set to the right-side USING columns and passed to `LogicalJoin`, regardless of
join type. This meant the left-side column always served as the merge key in
`SELECT *`.
## Solution
Move merge key logic from `LogicalJoin` to a `LogicalProject` wrapping the
join:
1. **Remove `exceptAsteriskOutputs` from `LogicalJoin`** — the join should
output all columns normally.
2. **Add `exceptAsteriskOutputs` to `LogicalProject`** with
`DiffOutputInAsterisk` support.
3. **In `bindUsingJoin()`**, wrap the `LogicalJoin` with a `LogicalProject`
that selects the correct merge key based on join type:
- LEFT/INNER/LEFT SEMI/LEFT ANTI → `Alias(left_slot, name)`
- RIGHT/RIGHT SEMI/RIGHT ANTI → `Alias(right_slot, name)` (preserved side)
- FULL OUTER → `Alias(Coalesce(left_slot, right_slot), name)`
- Qualified USING columns (`t1.a`, `t2.a`) are excluded from asterisk
output; only the unqualified merge key appears in `SELECT *`.
## Files Changed
| File | Change |
|------|--------|
| `LogicalJoin.java` | Remove `exceptAsteriskOutputs` field and related
methods |
| `LogicalProject.java` | Add `exceptAsteriskOutputs` field +
`DiffOutputInAsterisk` support |
| `BindExpression.java` | Rewrite `bindUsingJoin()` to add merge-key Project
on top of Join |
| `LogicalPlanDeepCopier.java` | Copy `exceptAsteriskOutputs` when
deep-copying LogicalProject |
| `BindUsingJoinTest.java` | New test file with 14 test scenarios |
## Behavior
For `t1(a, b) RIGHT JOIN t2(a, c) USING(a)` with a right-only row (t2.a=5,
t2.c=10, no match in t1):
| Reference | Result |
|-----------|--------|
| `SELECT *` | `a=5, b=NULL, c=10` |
| `SELECT a` | `5` (unqualified → merge key from right preserved side) |
| `SELECT t1.a` | `NULL` (qualified → join original value) |
| `SELECT t2.a` | `5` (qualified → join original value) |
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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