timeout exceeded when trying to connect

[PsyTae]

We are running a VERY recent version of pg

admin@ip-10-0-0-58:~/nodeCode/webProd$ npm ls pg
[email protected] /home/admin/nodeCode/webProd
└── [email protected]

I have the following db connection file for both MySQL connection and Postgres connections.

const mysql = require('mysql'); // mysql
const pg = require('pg'); // postgres
//--- My SQL Connection -----------------------------------------------------------------------------------------------------------------

const mysqlConfig = {
    connectionLimit: 10,
    waitForConnections: true,
    host: process.env.MYSQL_HOST,
    port: process.env.MYSQL_PORT,
    user: process.env.MYSQL_USER,
    password: process.env.MYSQL_PASS,
    database: process.env.MYSQL_DATABASE
};

const postgisConfig = {
    host: process.env.POSTGIS_HOST,
    user: process.env.POSTGIS_USER,
    password: process.env.POSTGIS_PASS,
    database: process.env.POSTGIS_DATABASE,
    port: process.env.POSTGIS_PORT,
    max: 20,
    idleTimeoutMillis: 30000,
    connectionTimeoutMillis: 2000
};

const mysqlConn = mysql.createPool(mysqlConfig);
const postGisConn = new pg.Pool(postgisConfig);

mysqlConn.on('error', err => {
    console.error('Mysql Error:', err);
});

postGisConn.on('error', (err, client) => {
    console.error('PostGis Error', err);
});

module.exports.mysql = mysqlConn;
module.exports.postGis = postGisConn;

We use the exported pool connection from this file for queries to the db throughout the rest of the project.

const postGisConn = require('./dbConn').postGis;
...

    let gisSelect = {
        text: `SELECT
            <COLUMN1>,
            <COLUMN2>,
            <COLUMN3>,
            <COLUMN4>
        FROM <TABLE>
        WHERE <COLUMN5>= '${req.body.<VARIABLE>}'`
    };
    // console.log(gisSelect.text);
    // cb();
    postGisConn.query(gisSelect, cb);

the documentation found at https://node-postgres.com/api/pool seems to suggest this is perfectly acceptable, however, we are constantly getting this error, all over when running our code.

Error: timeout exceeded when trying to connect
    at Timeout.setTimeout [as _onTimeout] (/home/admin/nodeCode/ParticleRoutes/node_modules/pg-pool/index.js:188:27)
    at ontimeout (timers.js:436:11)
    at tryOnTimeout (timers.js:300:5)
    at listOnTimeout (timers.js:263:5)
    at Timer.processTimers (timers.js:223:10)

I can't figure out why especially since the documentation specifically says pool.query doesn't need a releaseCallback

Notice in the example above no releaseCallback was necessary. The pool is doing the acquiring and releasing internally. I find pool.query to be a handy shortcut in a lot of situations.

All my research seems to suggest though that this error was because I was exhausting the available idle connections and new ones are not being acquired, if so what are we doing wrong?

[PsyTae]

Duplicate of #2262