RedixSharding

Drop-in replacement for Redix with sharding and pooling support

Usage

opts = [
  pools: [
    default: [
      urls: ["redis://localhost:6379", "redis://localhost:6380", "redis://localhost:6381", "redis://localhost:6382"],
      connection: 1],
    index: [
      urls: ["redis://localhost:6383", "redis://localhost:6384"],
      connection: 2]
  ]
]

RedixSharding.start_link(opts)

RedixSharding.command(["INCRBY", "{default@foo5}", 1])

RedixSharding.pipeline([["INCRBY", "{default@foo5}", 1]])

In the opts configuration above, we have configured 2 pools:

• Pool default has 4 shards, for each shard we will maintain 1 active connection in the pool
• Pool index has 2 shards, for each shard we will maintain 2 active connections, requests send to each shard will be distributed between 2 active connections

Sharding Rule:

There are 2 concepts you need to grasp here:

• pool_name: denotes the name of the pool to send requests, different pools are totally separated from each other
• shard_key: the key used to calculate the shard current key goes to, we will do a CRC32 calculation on the shard key, the mod the number of shards in the pool to get the shard index for current key. Notice due to following rules, a shard key can be the full key or part of the full key.

For commands that will require multiple keys, we will calculate the pool name and shard key for each key, and we would only run the command if all key maps to the same pool and same shard

full key	pool name	shard key
Foo:bar	default	Foo:bar
Foo{}bar	default	Foo{}bar
{Foo}bar	default	Foo
{default@Foo}bar	default	default@Foo
{index@Foo}bar	index	index@Foo
{@Foo}bar	default	@Foo
{Foo}:bar:{Baz}	default	Foo
{Foo}:bar:{index@Baz}	default	Foo