issue: #44358
Implement complete snapshot management system including creation,
deletion, listing, description, and restoration capabilities across all
system components.
Key features:
- Create snapshots for entire collections
- Drop snapshots by name with proper cleanup
- List snapshots with collection filtering
- Describe snapshot details and metadata
Components added/modified:
- Client SDK with full snapshot API support and options
- DataCoord snapshot service with metadata management
- Proxy layer with task-based snapshot operations
- Protocol buffer definitions for snapshot RPCs
- Comprehensive unit tests with mockey framework
- Integration tests for end-to-end validation
Technical implementation:
- Snapshot metadata storage in etcd with proper indexing
- File-based snapshot data persistence in object storage
- Garbage collection integration for snapshot cleanup
- Error handling and validation across all operations
- Thread-safe operations with proper locking mechanisms
<!-- This is an auto-generated comment: release notes by coderabbit.ai
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- Core invariant/assumption: snapshots are immutable point‑in‑time
captures identified by (collection, snapshot name/ID); etcd snapshot
metadata is authoritative for lifecycle (PENDING → COMMITTED → DELETING)
and per‑segment manifests live in object storage (Avro / StorageV2). GC
and restore logic must see snapshotRefIndex loaded
(snapshotMeta.IsRefIndexLoaded) before reclaiming or relying on
segment/index files.
- New capability added: full end‑to‑end snapshot subsystem — client SDK
APIs (Create/Drop/List/Describe/Restore + restore job queries),
DataCoord SnapshotWriter/Reader (Avro + StorageV2 manifests),
snapshotMeta in meta, SnapshotManager orchestration
(create/drop/describe/list/restore), copy‑segment restore
tasks/inspector/checker, proxy & RPC surface, GC integration, and
docs/tests — enabling point‑in‑time collection snapshots persisted to
object storage and restorations orchestrated across components.
- Logic removed/simplified and why: duplicated recursive
compaction/delta‑log traversal and ad‑hoc lookup code were consolidated
behind two focused APIs/owners (Handler.GetDeltaLogFromCompactTo for
delta traversal and SnapshotManager/SnapshotReader for snapshot I/O).
MixCoord/coordinator broker paths were converted to thin RPC proxies.
This eliminates multiple implementations of the same traversal/lookup,
reducing divergence and simplifying responsibility boundaries.
- Why this does NOT introduce data loss or regressions: snapshot
create/drop use explicit two‑phase semantics (PENDING → COMMIT/DELETING)
with SnapshotWriter writing manifests and metadata before commit; GC
uses snapshotRefIndex guards and
IsRefIndexLoaded/GetSnapshotBySegment/GetSnapshotByIndex checks to avoid
removing referenced files; restore flow pre‑allocates job IDs, validates
resources (partitions/indexes), performs rollback on failure
(rollbackRestoreSnapshot), and converts/updates segment/index metadata
only after successful copy tasks. Extensive unit and integration tests
exercise pending/deleting/GC/restore/error paths to ensure idempotence
and protection against premature deletion.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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Signed-off-by: Wei Liu <wei.liu@zilliz.com>
