mysql-redis 🚀

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

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 everytime.

• 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:

farmhash32 ⚡🗜️ Example redis key: prefix.2jNDCJ Fast!!! Over ~5 million hashes/s on reference machine. Most compact key.

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 💥) so use it for hundreds or thousands of static queries

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 farmhash.

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 might be more compact for 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 redis-async

Installing

npm i mysql-redis --save

Usage

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

// or if you use async await api
const { MysqlRedisAsync, HashTypes } = 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)

const cacheOptions = {
    expiry: 2629746,// seconds, defaults to 30 days 
    keyPrefix: "sql.", // default
    hashType: HashTypes.farmhash32 //default
};

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 
	}, 
	(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 
	});

Contributing

Feel free to fork/send PR

Authors

• Gi Singh

License

This project is licensed under the MIT.