Pool

new Pool([config: String | PoolConfiguration)

Properties

Key	Type	Readonly	Description
config	PoolConfiguration]	true	Returns configuration object
acquiredConnections	number	true	Returns number of connections that are currently acquired
idleConnections	number	true	Returns number of unused connections in the pool
acquiredConnections	number	true	Returns number of connections that are currently acquired
totalConnections	number	true	Returns total number of connections in the pool regardless of whether they are idle or in use

Methods

acquire()

Obtains a connection from the connection pool

acquire(): Promise<PoolConnection>

• Returns Connection

import { Pool } from 'postgrejs';

const pool = new Pool('postgres://localhost');
const connection = await pool.acquire();
// ...
await connection.close();

close()

Shuts down the pool and destroys all resources.

close(terminateWait?: number): Promise<void>

import { Pool } from 'postgrejs';

const pool = new Pool('postgres://localhost');
const connection = await pool.acquire();
// ...
await pool.close(5000);

execute()

Acquires a connection from the pool and executes single or multiple SQL scripts using Simple Query protocol.

execute(sql: string, options?: ScriptExecuteOptions): Promise<ScriptResult>;

Argument	Type	Default	Description
sql	string		SQL script that will be executed
options	ScriptExecuteOptions		Execute options

• Returns ScriptResult

import { Pool } from 'postgrejs';

const pool = new Pool('postgres://localhost');
const executeResult = await pool.execute(
        'BEGIN; update my_table set ref=1 where id=1; END;');
// ...
await pool.close();

query()

Acquires a connection from the pool and executes single SQL script using Extended Query protocol.

query(sql: string, options?: ScriptExecuteOptions): Promise<ScriptResult>;

Argument	Type	Default	Description
sql	string		SQL script that will be executed
options	QueryOptions		Execute options

• Returns QueryResult

import { Pool } from 'postgrejs';

const pool = new Pool('postgres://localhost');
const queryResult = await pool.query(
        'select * from my_table', {
            cursor: true,
            utcDates: true
        });
let row;
while ((row = await queryResult.cursor.next())) {
    // ....
}
await pool.close();

prepare()

Acquires a connection from the pool and creates a PreparedStatement instance.

prepare(sql: string, options?: StatementPrepareOptions): Promise<PreparedStatement>

Argument	Type	Default	Description
sql	string		SQL script that will be executed
options	StatementPrepareOptions		Options

• Returns PreparedStatement

import { Pool, DataTypeOIDs } from 'postgrejs';

const pool = new Pool('postgres://localhost');
const statement = await pool.prepare(
        'insert into my_table (ref_number) ($1)', {
            paramTypes: [DataTypeOIDs.Int4]
        });
// Bulk insert 100 rows
for (let i = 0; i < 100; i++) {
    await statement.execute({params: [i]});
}
await statement.close();

release()

Releases a connection

release(connection: Connection): Promise<void>

listen()

Registers the pool as a listener on the notification channel.

listen(channel: string, callback: NotificationCallback): Promise<void>

Argument	Type	Default	Description
channel	string		Name of the channel
callback	NotificationCallback		Listener callback function

await pool.listen('my_event', (msg: NotificationMessage)=>{
  console.log(msg.channel+ ' event fired!. processId:', msg.processId, '  payload:', msg.payload);
});

unListen()

Removes existing registration for NOTIFY events for given channel.

unListen(channel: string): Promise<void>

Argument	Type	Default	Description
channel	string		Name of the channel

await pool.unListen('my_event');

unListenAll()

Removes existing registration for NOTIFY events for all channels.

unListenAll(): Promise<void>

await pool.unListenAll();