mysql-redis :rocket:

Transform your mysql server with Redis caching layer for mysql/mysql2.

• MysqlRedis checks if there is a cached result for the query in redis
• if not found in cache, it will retrieve data from mysql and on successful result cache it in redis for future queries
• if redis is unavailable or errors, query will be served by mysql
• zero external dependency (farmhash is now option after v0.7)

Use-case

Use along with mysql and redis. This is not a replacement of either. Use it with queries/stored procedures that only perform select and will return same result set every time.

• No brainer for retrieving static data, eg, select * from countries
• Data that will not be updated once created, typically timeseries data like chat messages, logs
• Use with caution where data may get updated in mysql as redis cache may be stale

Hashing

The above is achieved by creating a unique hash for every query

"select 1+2" => #️⃣

In redis, the hash and query results are stored as key-value pair

#️⃣ => [{'1+2':3}]

Currently supported hash types are:

md5hash ⚡🗜️ MD5hash is the new default to prevent non mandatory dependency on farmhash MD5 hash is generated without any external lib

farmhash32 ⚡🗜️ Example redis key: prefix.2jNDCJ Fast!!! Over ~5 million hashes/s on reference machine. Most compact key. (if you have millions of possible queries, these hashes can collide :collision:)

farmhash64 Example redis key: prefix.DiHlF3yv0V$ fast (~2 million hashes/sec on reference machine ) farmhash32/64 use Google's farmhash, non-crypto algorithm (if you have millions of possible queries, these hashes can collide :collision:)

blake2b512 🛡️ Example redis key: prefix.4KbMOx3xJi+7mJNy0tDbju6NY9uHqOroDsG4rYjpHK1mEwXJokls5Ofdjs7iDsn3cAtibgUkT8RDdpCE2phhiQ== Crypto safe, ~500k hashes/sec on reference machine. Use it for caching millions of different queries (eg. chats, logs) Note that the key is longer than farmhash32/64.

full Matches full query string. Use this if you are paranoid or if your queries are smaller than blake2b512 hashes

Or you can provide your own hash per query, eg, prefix.p.123 to represent select * from person p where id = 123

Getting Started

Pre-Requisites

mysql (mysql/mysql2), and redis (redis/ioredis). Internally MysqlRedis relies on mysql/mysql2's query function and redis's get and set functions

For async/await api, you can use mysql2's promise api and async-redis

Installing

npm i mysql-redis --save

Usage

const { MysqlRedis, HashTypes, Caching } = require("mysql-redis");

// or if you use async await api
const { MysqlRedisAsync, HashTypes, Caching } = require("mysql-redis");

Creating an instance of MysqlRedis requires

• a mysql connection or pool (mysqlRedis will call it's query method when no cache found)
• redis connection (mysqlRedis will call its set and get methods)
• cache options (optional)

Creating an instance of MysqlRedisAsync requires

• a mysql connection or pool promise // Example from mysql2 docs: const poolPromise = mysql.createPool({ host:'localhost', user: 'root', database: 'test' }) .promise();

• async redis

  eg:
  const asyncRedis = require("async-redis");
  const redis = asyncRedis.createClient(redisOptions);
  
      	```
  

• cache options (optional)

import HashTypes and Caching from mysql-redis

const cacheOptions = {
    expire: 2629746,// seconds, defaults to 30 days
    keyPrefix: "sql.", // default
    hashType: HashTypes.md5 //default
    caching: Caching.CACHE //default
};

hashType can be

• HashTypes.farmhash32
• HashTypes.farmhash64
• HashTypes.blake2b512
• HashTypes.full

caching can be

• Caching.CACHE to get data from Redis if available, else mysql
• Caching.SKIP to get data from mysql, do not save to redis
• Caching.REFRESH to get data from mysql and save to redis

Options can be specified when creating mysqlRedis instance or overriden at the time of query. At query time, you can also provide a custom hash as cacheOptions.hash (ignores hashType if specified)

const mysqlRedis = new MysqlRedis(
    mysqlConnection,
    redisConnection,
    cacheOptions
);

Now if you wish to get something from cache, just use mysqlRedis.query instead of your mysql connection's query. (Use your mysql connection normally to bypass cache)

mysqlRedis.query('select * from logs where id =?",["some-log-id"], (err,data,fields)=>{
	console.log(data)
	// if served by Redis, fields value is something like [ { cacheHit: 'sql.Dh9VSNbN5V$' } ]
	// else mysql fields
});

or if you like promises, then:

const mysqlRedis = new MysqlRedisAsync(
    mysqlConnection,
    redisConnection,
    cacheOptions
);

... in an async function ...
try{

	[result,fields]=await mysqlRedis.query("select 1+?+?",[2,3]);

}catch(err){
	// handle err
}

You can override cache options per query as below:

mysqlRedis.query('select * from logs where id =?",["some-log-id"],
	{ //cache option
		keyPrefix:'sql-abc-',
		expire:3600,
		hashType: HashTypes.farmhash64
        //or hash: myHash <- provide your own
        // caching: Caching.SKIP or Caching.REFRESH or Caching.CACHE
	},
	(err,data,fields)=>{
	console.log(data)
	// if served by Redis, fields value is something like [ { cacheHit: 'sql.Dh9VSNbN5V$' } ]
	// else mysql fields
});


// promise api
[result,fields]=await mysqlRedis.query("select 1+?+?",[2,3],
   { //cache option
		keyPrefix:'sql-abc-',
		expire:3600,
		hashType: HashTypes.farmhash64
        //or hash: myHash <- provide your own
        // caching: Caching.SKIP or Caching.REFRESH or Caching.CACHE
	});

Testing

• Start mysql and redis servers on your local (host 127.0.0.1, default ports)
• create user test_user in mysql, no need to give any grants

CREATE USER 'test_user'@'%' IDENTIFIED BY PASSWORD 'User@123';

• then run npm run test

Contributing

Feel free to fork/send PR

Authors

• Gi Singh

License

This project is licensed under the MIT.