Repository navigation
[server] Register external KV snapshots and restore replicas - #4242
Open
platinumhamburg wants to merge 8 commits into
Open
platinumhamburg wants to merge 8 commits into
platinumhamburg wants to merge 8 commits into
Conversation
Contributor
There was a problem hiding this comment.
Copilot review overview
🟡 Changes recommended
Critical snapshot integrity and manifest validation are missing, and metadata versions are not validated.
Get a fresh assessment by requesting another Copilot review.
Review effort: Lite
Findings: 2
Open (3)
What changed in this PR
Adds external KV snapshot registration, retention, and replica restoration support.
Changes:
- Adds portable snapshot metadata serialization.
- Registers external snapshots in ZooKeeper with retry and retention handling.
- Restores replicas from external snapshots and initializes log tails.
- Adds recovery, registration, retention, and compatibility tests.
| File | Summary |
|---|---|
fluss-server/src/test/java/org/apache/fluss/server/replica/ReplicaTest.java |
Tests replica recovery behavior. |
fluss-server/src/test/java/org/apache/fluss/server/log/LogTabletTest.java |
Tests log-tail initialization. |
fluss-server/src/test/java/org/apache/fluss/server/kv/snapshot/TestCompletedSnapshotHandleStore.java |
Updates test snapshot-store implementation. |
fluss-server/src/test/java/org/apache/fluss/server/coordinator/ExternalKvSnapshotITCase.java |
Tests external snapshot recovery end to end. |
fluss-server/src/test/java/org/apache/fluss/server/coordinator/CoordinatorServiceOrphanRpcsITCase.java |
Updates test-store fixtures. |
fluss-server/src/test/java/org/apache/fluss/server/coordinator/CompletedSnapshotStoreManagerTest.java |
Tests registration and retention scenarios. |
fluss-server/src/main/java/org/apache/fluss/server/zk/ZooKeeperClient.java |
Adds idempotent external snapshot registration. |
fluss-server/src/main/java/org/apache/fluss/server/replica/Replica.java |
Integrates snapshot-based KV recovery. |
fluss-server/src/main/java/org/apache/fluss/server/log/LogTablet.java |
Supports empty log-tail initialization. |
fluss-server/src/main/java/org/apache/fluss/server/log/LogManager.java |
Persists initialized log tails. |
fluss-server/src/main/java/org/apache/fluss/server/kv/snapshot/ZooKeeperCompletedSnapshotHandleStore.java |
Implements ZooKeeper-backed external registration. |
fluss-server/src/main/java/org/apache/fluss/server/kv/snapshot/CompletedSnapshotStore.java |
Integrates external snapshots with retention. |
fluss-server/src/main/java/org/apache/fluss/server/kv/snapshot/CompletedSnapshotJsonSerde.java |
Adapts server snapshots to portable metadata. |
fluss-server/src/main/java/org/apache/fluss/server/kv/snapshot/CompletedSnapshotHandleStore.java |
Extends the snapshot handle-store contract. |
fluss-server/src/main/java/org/apache/fluss/server/coordinator/CompletedSnapshotStoreManager.java |
Registers and tracks external snapshots. |
fluss-common/src/test/java/org/apache/fluss/metadata/KvSnapshotFileMetadataJsonSerdeTest.java |
Tests metadata serialization compatibility. |
fluss-common/src/main/java/org/apache/fluss/metadata/KvSnapshotFileMetadataJsonSerde.java |
Serializes and deserializes portable metadata. |
fluss-common/src/main/java/org/apache/fluss/metadata/KvSnapshotFileMetadata.java |
Defines portable snapshot metadata. |
💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.
Share KV snapshot file metadata across modules and register externally produced target-bucket snapshots with coordinator fencing and idempotent retries. Adopt confirmed snapshots into retention and protect persistent references when registration responses are lost. Initialize the local log boundary from snapshot-only history through ordinary replica role notifications. Cover external snapshot production, registration, recovery, repeated notifications, online writes, failover and subsequent snapshot retention.
Use the selected KV snapshot to initialize an empty local log after its files have been loaded, and capture the leader log boundary after recovery. Reject conflicting log initialization and propagate snapshot lookup errors. Release partially recovered KV state before retrying, and publish leader identity only after recovery succeeds so failed elections can be retried. Cover snapshot lookup and download failures, metadata retry after loading, and protection of existing local log records.
Keep the existing leader and follower transition behavior while coordinating KV snapshot recovery with local log initialization. Test snapshot lookup failures independently of role transition retries, and recover from a failed download under a subsequent leader epoch.
Serialize external snapshot identity and ordering checks, persistent handle confirmation and retention updates in CompletedSnapshotStore. Delegate coordinator fencing and idempotent persistence to the handle store while preserving ordinary snapshot writes and cleanup behavior. Describe the snapshot counter check as an allocation bound; reserving the ID remains the caller's responsibility.
platinumhamburg
force-pushed
the
feature-kv-snapshot-import
branch
from
September 21, 2026 02:04
097aacc to
0e0ab1f
Compare
Resolve the recovery snapshot and log prerequisites before changing role state or discarding the current KV. Reuse that selection for the first recovery attempt while preserving retries through older healthy snapshots. Avoid remote manifest lookups when the local log already covers the snapshot. Cover metadata lookup failures with a live KV and recovery after metadata becomes available. Clarify that obsolete snapshot cleanup may be deferred.
platinumhamburg
force-pushed
the
feature-kv-snapshot-import
branch
from
September 21, 2026 02:33
0e0ab1f to
4a1fb0a
Compare
Wait for KV replicas before bounded snapshot split enumeration. Keep synthetic orphan-cleanup snapshot metadata from participating in leader recovery, and let replica readiness checks retry while the leader or tablet server is temporarily unavailable.
Contributor
Author
|
Addressing the three Copilot review comments:
|
wuchong
approved these changes
Oct 13, 2026
wuchong
left a comment
wuchong
left a comment
Member
There was a problem hiding this comment.
LGTM. Please rebase to resolve the conflicts.
It seems the org.apache.fluss.server.coordinator.CompletedSnapshotStoreManager#registerExternalSnapshot is not invoked yet, IIUC, it will be integreated into Coordinator RPC in follow-up PRs?
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Purpose
Linked issue: close #4223
Brief change log
Tests
API and Format
Documentation