Mryange opened a new pull request, #63491:
URL: https://github.com/apache/doris/pull/63491
### What problem does this PR solve?
The null_map column in `ColumnNullable` was stored as a generic
`IColumn::WrappedPtr`, requiring `assert_cast<ColumnUInt8>` at every call site
that accessed it. This had two problems:
1. **Redundant runtime casts**: Every access to `get_null_map_column()` or
`get_null_map_column_ptr()` performed an `assert_cast`, adding unnecessary
overhead on hot paths (filter evaluation, null propagation, etc.).
2. **Type safety**: The generic `WrappedPtr` type provided no compile-time
guarantee that the null map is always a `ColumnUInt8`, making it possible to
accidentally store a wrong column type.
Root cause: The `_null_map` member was typed as a generic
`IColumn::WrappedPtr` instead of the concrete `ColumnUInt8::WrappedPtr`.
Fix: Change `_null_map` to `ColumnUInt8::WrappedPtr` so the type is fixed at
the member level. The constructor now validates and converts to
`ColumnUInt8::MutablePtr` on entry via a helper `assert_mutable_null_map()`.
All call sites that previously did `assert_cast<ColumnUInt8>` now get the
correct type directly.
### Release note
None
### Check List (For Author)
- Test <!-- At least one of them must be included. -->
- [ ] Regression test
- [ ] Unit Test
- [ ] Manual test (add detailed scripts or steps below)
- [ ] No need to test or manual test. Explain why:
- [ ] This is a refactor/code format and no logic has been changed.
- [ ] Previous test can cover this change.
- [ ] No code files have been changed.
- [ ] Other reason <!-- Add your reason? -->
- Behavior changed:
- [ ] No.
- [ ] Yes. <!-- Explain the behavior change -->
- Does this need documentation?
- [ ] No.
- [ ] Yes. <!-- Add document PR link here. eg:
https://github.com/apache/doris-website/pull/1214 -->
### Check List (For Reviewer who merge this PR)
- [ ] Confirm the release note
- [ ] Confirm test cases
- [ ] Confirm document
- [ ] Add branch pick label <!-- Add branch pick label that this PR should
merge into -->
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