milvus/internal
congqixia 6f94d8c41a
fix: Handle legacy binlog format (v1) in segment load diff computation (#46598)
When computing load diff, binlogs in v1/legacy format have empty
child_fields. In this case, the field_id itself should be used as the
child_id (group_id == field_id for legacy format).

Without this fix, legacy format binlogs are not recognized during diff
computation, causing segments to fail loading and TestProxy to timeout.

Changes:
- Add fallback to use fieldid as child_id when child_fields is empty
- Add LoadDiff::ToString() for debugging
- Add logging for diff in Load/Reopen operations
- Add comprehensive unit tests for legacy format handling

Related to #46594

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
- Core invariant: load-diff computation must enumerate every binlog
child group for a field so current vs new segment state comparisons
include all column-group/binlog groups; for legacy (v1) binlogs that
have empty child_fields, the code must treat group_id == field_id to
preserve that mapping.
- Bug fix (resolves #46594): SegmentLoadInfo now normalizes
field_binlog.child_fields() into a vector and falls back to using
field_id as the single child group when child_fields is empty; the same
normalization is applied for both current and new-info paths, ensuring
legacy v1 binlogs are discovered and included in Load/ComputeDiff
results so segments load correctly.
- Logic simplified: removed the implicit assumption that child_fields is
always present by centralizing a single normalization/fallback step used
symmetrically for both diff paths, avoiding ad-hoc special-casing and
unifying iteration over child groups.
- No data loss / no behavior regression: the fallback only activates
when child_fields is empty — non-legacy binlogs continue to use their
child_fields unchanged. Add/drop semantics are preserved because the
same normalization is applied to both sides of the diff. Unit tests
(v1-only, v4-only, mixed cases) were added to validate correctness;
LoadDiff::ToString() and extra logging are diagnostic only.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Co-authored-by: Cai Zhang <cai.zhang@zilliz.com>

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Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>
2025-12-25 23:33:19 +08:00
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