bitraft/README.md

# kvnode

Minimal Key/Value store with basic Redis support. 

- Redis API
- LevelDB disk-based storage
- Raft support with [Finn](https://github.com/tidwall/finn) commands
- Compatible with existing Redis clients

Commands:

```
SET key value
GET key
DEL key [key ...]
PDEL pattern
KEYS pattern [PIVOT prefix] [LIMIT count] [DESC] [WITHVALUES]
MSET key value [key value ...]
MGET key [key ...]
FLUSHDB
SHUTDOWN
```

## Key scanning

The `KEYS` command returns keys and values, ordered by keys. 
The `PIVOT` keyword allows for efficient paging.
For example:
```
redis> MSET key1 1 key2 2 key3 3 key4 4
OK
redis> KEYS * LIMIT 2
1) "key1"
2) "key2"
redis> KEYS * PIVOT key2 LIMIT 2
1) "key3"
2) "key4"
```

The `PDEL` commands will delete all items matching the specified pattern.


## Backup and Restore

To backup data:
```
RAFTSNAPSHOT
```
This will creates a new snapshot in the `data/snapshots` directory.
Each snapshot contains two files, `meta.json` and `state.bin`.
The state file is the database in a compressed format. 
The meta file is details about the state including the term, index, crc, and size.

Ideally you call `RAFTSNAPSHOT` and then store the state.bin on some other server like S3.

To restore:
- Create a new raft cluster
- Download the state.bin snapshot
- Pipe the commands using the `kvnode-server --parse-snapshot` and `redis-cli --pipe` commands

Example:
```
kvnode-server --parse-snapshot state.bin | redis-cli -h 10.0.1.5 -p 4920 --pipe
```

This will execute all of the `state.bin` commands on the leader at `10.0.1.5:4920`


For information on the `redis-cli --pipe` command see [Redis Mass Insert](https://redis.io/topics/mass-insert).

## Contact
Josh Baker [@tidwall](http://twitter.com/tidwall)

## License
kvnode source code is available under the MIT [License](/LICENSE).