pg-cluster.

Description.

Simple module for building cluster with postgresql databases for node v >=7 with 1 dependencies(pg). Support replication mode, maintenance mode.

Install module.

npm install pg-cluster

Usage.

Cluster is class, and you can extend him by you custom cluster.

Define sample config.

Define sample config:
2 shards dev0, dev1(in maintenance) - in master mode
2 shards dev2, dev3 - in slave mode

const config = {
    dev0: {
        adapter: "postgresql"
        port: 5432,
        host: "127.0.0.1",
        database: "dev0",
        shard_id: "00",
        username: "postgres",
        password: "pass"
    },
    dev1: {
        adapter: "postgresql"
        port: 5432,
        host: "127.0.0.1",
        database: "dev1",
        shard_id: "01",
        username: "postgres",
        password: "pass",
        maintenance: true
    },

    dev_slave0: {
        adapter: "postgresql"
        port: 5432,
        host: "127.0.0.1",
        database: "dev2",
        shard_id: "00",
        username: "postgres",
        password: "pass",
        slave: true
    },
    dev_slave1: {
        adapter: "postgresql"
        port: 5432,
        host: "127.0.0.1",
        database: "dev3",
        shard_id: "01",
        username: "postgres",
        password: "pass",
        slave: true
    }
};

Init cluster.

const Cluster = require('pg-cluster');
const customLog = console.log;
try {
    const db = new Cluster(config, customLog);
    await db.masterMode(false); // want switch to replications cluster;
    await db.init();
} catch (e) {
    console.log("Some Error", err)
}

Create model.

const onSuccessGetByUserId = function(res, params, cb) {
    cb(res)
}

const onErrorGetByUserId = function(err, params, cb) {
    cb(err)
}

const getByUserId = function() {
    const firstSlaveShard = db.getById("00");
    const userId = "userId";
    return new Promise((cb ,rej)=> {
        firstSlaveShard.sqlQuery(`SELECT * FROM users WHERE user_id=$1;`,[userId])
           .success(onSuccessGetByUserId, cb)
           .error(onErrorGetByUserId, rej)
    })
}

Call sql request.

Call model method:
try {
    const res = await getByUserId()
} catch (e) {
    console.log("Some Error wit db request", err)
}

Close cluster when shoutdown your server, or reinit cluster.

db.close();

Errors: postgresql can return serious error with codes("08P01", "EPIPE"), if this happened, cluster set shard status on "error", and this shard is locked. You need try reconnect you broken shards.

if (db.hasBrokenShards)
    db.reconnectBrokenShards();

Main methods

db.init();
db.close();
db.masterMode();
db.hasBrokenShards();
db.reconnectBrokenShards();
db.randomShard();
db.getById();
db.afterInit();

License MIT