milvus-io
/
milvus
mirror of https://github.com/milvus-io/milvus.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Grammar and wording changes in datanode recovery design doc (#8265) 

Signed-off-by: NotRyan <ryan.chan@zilliz.com>

Co-authored-by: NotRyan <ryan.chan@zilliz.com>
pull/8064/head
NotRyan 2021-09-22 01:22:44 -07:00 committed by GitHub
parent bdfb78e936
commit 8a545a789f
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 7 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
docs/design_docs/datanode_recovery_design_0513_2021.md
View File

@ -8,17 +8,17 @@ update: 6.21.2021, by [Goose](https://github.com/XuanYang-cn)
DataNode processes insert data and persists them.
DataNode is based on flowgraph, each flowgraph cares about only one vchannel. There're ddl messages, dml
DataNode is based on flowgraph; each flowgraph cares about only one vchannel. There are ddl messages, dml
messages, and timetick messages inside one vchannel, FIFO log stream.
One vchannel only contains dml messages of one collection. A collection consists of many segments, hence
a vchannel contains dml messsages of many segments. **Most importantly, the dml messages of the same segment
a vchannel contains dml messsages of many segments. **Most importantly, the dml messages of the same segment
can appear in anywhere in vchannel.**
## What does DataNode recovery really mean?
DataNode is stateless, but vchannel has states. DataNode's statelessness is guranteed by DataCoord, which
means the vchannel's states is maintained by DataCoord. So DataNode recovery has no different as starting.
DataNode is stateless, but vchannel has states. DataNode's statelessness is guaranteed by DataCoord, which
means the vchannel's state is maintained by DataCoord. So DataNode recovery is no different from starting.
So what's DataNode's starting procedure?
@ -36,7 +36,7 @@ DataNode discovers DataCoord and RootCoord, in *HEALTHY* and *IDLE* state.
The detailed design can be found at [datanode flowgraph recovery design](datanode_flowgraph_recovery_design_0604_2021.md).
After DataNode subscribes to a stateful vchannel, DataNode starts to work, or more specifically, flowgraph starts to work.
After DataNode subscribes to a stateful vchannel, DataNode starts to work, or more specifically, flowgraph starts to work.
Vchannel is stateful because we don't want to process twice what's already processed. And a "processed" message means its
already persistant. In DataNode's terminology, a message is processed if it's been flushed.
@ -48,12 +48,12 @@ DataNode tells DataCoord vchannel states after each flush through RPC `SaveBinlo
keep the vchannel states update.
## Some of the following interface/proto designs are outdate, will be updated soon
## Some of the following interface/proto designs are outdated, will be updated soon
### 1. DataNode no longer interacts with Etcd except service registering
#### DataCoord rather than DataNode saves binlog paths into Etcd
![datanode_design](graphs/datanode_design_01.jpg)