CDC is "Change Data Capture", and Milvus-CDC is a change data capture tool for Milvus. It can capture the changes of upstream Milvus collections and sink them to downstream Milvus. This will bring the following benefits:

1. Data reliability is improved and the probability of data loss is reduced;
2. Based on CDC, the active-standby disaster recovery feature of milvus can be implemented to ensure that even if the milvus-source cluster fails, it can be quickly switched to ensure the availability of upper-layer services;

You can download the executable files in the release page or compile the source code to get the cdc tool.

• how to compile source code?

git clone https://github.com/zilliztech/milvus-cdc.git

make build

After successfully building, the cdc bin file will be generated in the server directory.

When you get the cdc bin file, DON'T execute it directly. If you do it, I think you must get an error because you need to configure it before using it. How to configure and use cdc, refer to: milvus cdc usage

At present, cdc mainly consists of two parts: http server and corelib.

• The http server, is responsible for accepting user-side requests, controlling task execution, and maintaining meta-information;
• corelib, is responsible for synchronizing the execution of tasks, including reader and writer:
  • reader reads relevant information from etcd and mq of source Milvus;
  • The writer converts the msg in mq into Milvus api parameters and sends the request to the target Milvus;

1. User creates cdc task through http interface;
2. Obtain collection-related meta-information through etcd in Milvus-source, such as the channel information and checkpoint information corresponding to the collection, etc;
3. After obtaining the meta-information related to the collection, connect to mq(message queue) to subscribe to the data;
4. Read the data in mq, parse the data and forward it through go-sdk or perform the same operation as milvus-source;