RedisTikvPoc

[POC] Redis Module for TiKV

This is a POC repository. This Redis Module will add branch new Redis commands to operate TiKV data.

After build the module you can use Redis MODULE LOAD command load it.

Build

> cargo build

Notice: If using GCC 11 you should add -include /usr/include/c++/11*/limits to CXXFLAGS.

Usage

> module load libredistikv.so
> tikv.conn 127.0.0.1:2379
> tikv.put key value
> tikv.get key
> tikv.load key
> tikv.del key
> tikv.scan prefix 10
> tikv.delrange start-key end-key
> pd.members 127.0.0.1:2379

Commands

Operate TiKV

• tikv.conn [PDSERVERADDR] [PDSERVERADDR] ... : connect to TiKV cluster, PDSERVERADDR is optional default is 127.0.0.1:2379
• tikv.set [KEY] [VALUE]: put a Key-Value pair into TiKV cluster.
• tikv.get [KEY]: read a key's value from TiKV cluster.
• tikv.del [KEY1] [KEY2] ...: delete keys from TiKV cluster.
• tikv.load [KEY]: read a key's value from TiKV cluster and use SET command save the key-value pair into Redis memory.
• tikv.scan [STARTKEY] [ENDKEY] [LIMIT]: scan TiKV cluster data's using given range STARTKEY to ENDKEY and return LIMIT rows. If ENDKEY is ignored the range is from STARTKEY to end.
• tikv.delrange [STARTKEY] [ENDKEY]: use delete_range API to delete many key's from TiKV cluster.
• tikv.mget [KEY1] [KEY2] ...: Same as Redis MGET.
• tikv.mset [KEY1] [VALUE1] [KEY2] [VALUE2] ...: Same as Redis MSET.
• tikv.exists [KEY1] [KEY2] ...: Same as Redis EXISTS.

Get PD API data

• pd.members [PDSERVERADDR]: request PD to get cluster members data.

Module Parameters

module load libredistikv.so [replacesys]

• replacesys: replace system command. If add this parameter RedisTiKV will try to add GET, SET command using TIKV.GET, TIKV.SET

Benchmark

In bench folder it contains a golang written program to do some basic performance test. As a result, read or write data from TiKV cluster will always slower than Redis SET and GET command.

As the implementation of Redis Module, it using block_client API to make it concurrency ready. So ONE operate latency will not get the top performance. And this is why benchmark for tikv serise commands is using worker pool to test in concurrency mode. As we can see if more workers in pool the better performance gets.

Replace System Commands

Change the redis.conf file, use rename-command configuration to change system command name to other name, then add replacesys parameter to MODULE LOAD command or loadmodule configuration command. For example:

redis.conf

rename-command SET OSET
rename-command GET OGET

loadmodule /usr/local/lib/libredistikv.so replacesys

Then the GET and SET command is replaced by TIKV.GET and TIKV.SET.

System Commands can be Replaced

• SET
• GET
• MSET
• MGET
• EXISTS
• DEL

About Key Encoding

If we not encode KEY, you can get and set any TiKV data. So this is very danger for using RedisModule with a TiKV which provide data for TiDB service. And without key encoding the module can not support multi data type such as Hash or List. So add a Key prefix is safe than without it and we can support more data type. The current key encoding format is:

$R_[DATATYPE(1Byte)]_[KEY(nByte)]

As the description it will use $R_ as fixed prefix for RedisModule used data. DATATYPE use 1 Byte to determine the data type for value. Such as Raw, Hash and etc.

Data Types may provided:

• Raw: Raw type key, used by GET, SET series commands, use char R
• Hash: Hash type key, used by HGET, HSET series commands, use char H
• List: List type key, used by LPOP, LPUSH series commands, use char L

Note: Key encoding is a draft. So it may change in future.