https://medium.com/p/d0fe7106c68a

db.ts

import fs from "fs";
import knex from "knex";
import env from "./env";

export default knex({
  client: "pg",

  connection: {
    ssl: env.PGSSLMODE === "verify-ca" && {
      cert: fs.readFileSync(env.PGSSLCERT, "ascii"),
      key: fs.readFileSync(env.PGSSLKEY, "ascii"),
      ca: fs.readFileSync(env.PGSSLROOTCERT, "ascii"),
      servername: env.PGSERVERNAME,
    },
  },
  
   // Cloud Functions limits concurrent executions to 1 per instance. You never
  // have a situation where a single function instance is processing two
  // requests at the same time. In most situations, only a single database
  // connection is needed.
  pool: {
    min: 0,
    max: 1,
  }
});