issue: https://github.com/milvus-io/milvus/issues/44123
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- Core invariant: legacy in-cluster CDC/replication plumbing
(ReplicateMsg types, ReplicateID-based guards and flags) is obsolete —
the system relies on standard msgstream positions, subPos/end-ts
semantics and timetick ordering as the single source of truth for
message ordering and skipping, so replication-specific
channels/types/guards can be removed safely.
- Removed/simplified logic (what and why): removed replication feature
flags and params (ReplicateMsgChannel, TTMsgEnabled,
CollectionReplicateEnable), ReplicateMsg type and its tests, ReplicateID
constants/helpers and MergeProperties hooks, ReplicateConfig and its
propagation (streamPipeline, StreamConfig, dispatcher, target),
replicate-aware dispatcher/pipeline branches, and replicate-mode
pre-checks/timestamp-allocation in proxy tasks — these implemented a
redundant alternate “replicate-mode” pathway that duplicated
position/end-ts and timetick logic.
- Why this does NOT cause data loss or regression (concrete code paths):
no persistence or core write paths were removed — proxy PreExecute flows
(internal/proxy/task_*.go) still perform the same schema/ID/size
validations and then follow the normal non-replicate execution path;
dispatcher and pipeline continue to use position/subPos and
pullback/end-ts in Seek/grouping (pkg/mq/msgdispatcher/dispatcher.go,
internal/util/pipeline/stream_pipeline.go), so skipping and ordering
behavior remains unchanged; timetick emission in rootcoord
(sendMinDdlTsAsTt) is now ungated (no silent suppression), preserving or
increasing timetick delivery rather than removing it.
- PR type and net effect: Enhancement/Refactor — removes deprecated
replication API surface (types, helpers, config, tests) and replication
branches, simplifies public APIs and constructor signatures, and reduces
surface area for future maintenance while keeping DML/DDL persistence,
ordering, and seek semantics intact.
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Signed-off-by: bigsheeper <yihao.dai@zilliz.com>
