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issue: #49831 ## What changed Vendor Milvus design documents into this repository under `docs/design-docs` as regular tracked files. - Keep only the design document content and assets under `docs/design-docs/design_docs/` and `docs/design-docs/assets/`. - Remove standalone repository metadata from the vendored directory, such as `README.md`, `CONTRIBUTING.md`, `MEP-TEMPLATE.md`, `COMMITTERS`, `MAINTAINERS`, `OWNERS`, `OWNERS_ALIASES`, and `.gitignore`. - Document the Milvus design document process in the main `CONTRIBUTING.md`. - Update Mergify and `tools/mgit.py` so feature PRs must provide an in-repo design document path under `docs/design-docs/design_docs/`. ## Why Milvus feature work should have an associated design document. Keeping design docs directly in this repository makes them available from a normal Milvus checkout and lets feature implementations include or link the related design document in the same repository. ## Verification - `git diff --check` - `python3 -m unittest tools/test_mgit_design_doc.py` - `python3 -m py_compile tools/mgit.py tools/test_mgit_design_doc.py` - Parsed `.github/mergify.yml` with Python `yaml.safe_load` - Confirmed `docs/design-docs` only contains `assets/` and `design_docs/` at the top level --------- Signed-off-by: xiaofanluan <xiaofan.luan@zilliz.com> Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
2.4 KiB
2.4 KiB
DataNode Flowgraph Recovery Design
update: 6.4.2021, by Goose update: 6.21.2021, by Goose
1. Common Sense
A. One message stream to one vchannel, so there are one start and one end position in one message pack.
B. Only when DataNode flushes, DataNode will update every segment's position. An optimization: update position of
- Current flushing segment
- StartPosition of segments has never been flushed.
C. DataNode auto-flush is a valid flush.
D. DDL messages are now in DML Vchannels.
2. Segments in Flowgraph
3. Flowgraph Recovery
A. Save checkpoints
When a flowgraph flushes a segment, we need to save these things:
- current segment's binlog paths.
- current segment positions.
- all other segments' current positions from the replica (If a segment hasn't been flushed, save the position when DataNode first meets it).
Whether save successfully:
- If succeeded, flowgraph updates all segments' positions to the replica.
- If not
- For a grpc failure(this failure will appear after many times retry internally), crash itself.
- For a normal failure, retry save 10 times, if still fails, crash itself.
B. Recovery from a set of checkpoints
- We need all positions of all segments in this vchannel
p1, p2, ... pn.
Proto design for WatchDmChannelReq:
message VchannelInfo {
int64 collectionID = 1;
string channelName = 2;
msgpb.MsgPosition seek_position = 3;
repeated SegmentInfo unflushedSegments = 4;
repeated int64 flushedSegments = 5;
}
message WatchDmChannelsRequest {
common.MsgBase base = 1;
repeated VchannelInfo vchannels = 2;
}
- We want to filter msgPacks based on these positions.
Supposing we have segments s1, s2, s3, corresponding positions p1, p2, p3
- Sort positions in reverse order
p3, p2, p1 - Get segments dup range time:
s3 ( p3 > mp_px > p1),s2 (p2 > mp_px > p1),s1(zero) - Seek from the earliest, in this example
p1 - Then for every msgPack after seeking
p1, the pseudocode:
const filter_threshold = recovery_time
// mp means msgPack
for mp := seeking(p1) {
if mp.position.endtime < filter_threshold {
if mp.position < p3 {
filter s3
}
if mp.position < p2 {
filter s2
}
}
}