$ npm install pg
var pg = ;// instantiate a new client// the client will read connection information from// the same environment variables used by postgres cli toolsvar client = ;// connect to our databaseclient;
If you're working on something like a web application which makes frequent queries you'll want to access the PostgreSQL server through a pool of clients. Why? For one thing, there is ~20-30 millisecond delay (YMMV) when connecting a new client to the PostgreSQL server because of the startup handshake. Furthermore, PostgreSQL can support only a limited number of clients...it depends on the amount of ram on your database server, but generally more than 100 clients at a time is a very bad thing. ™️ Additionally, PostgreSQL can only execute 1 query at a time per connected client, so pipelining all queries for all requests through a single, long-lived client will likely introduce a bottleneck into your application if you need high concurrency.
With that in mind we can imagine a situation where you have a web server which connects and disconnects a new client for every web request or every query (don't do this!). If you get only 1 request at a time everything will seem to work fine, though it will be a touch slower due to the connection overhead. Once you get >100 simultaneous requests your web server will attempt to open 100 connections to the PostgreSQL backend and 💥 you'll run out of memory on the PostgreSQL server, your database will become unresponsive, your app will seem to hang, and everything will break. Boooo!
Good news: node-postgres ships with built in client pooling. Client pooling allows your application to use a pool of already connected clients and reuse them for each request to your application. If your app needs to make more queries than there are available clients in the pool the queries will queue instead of overwhelming your database & causing a cascading failure. 👍
var pg = ;// create a config to configure both pooling behavior// and client options// note: all config is optional and the environment variables// will be read if the config is not presentvar config =user: 'foo' //env var: PGUSERdatabase: 'my_db' //env var: PGDATABASEpassword: 'secret' //env var: PGPASSWORDhost: 'localhost' // Server hosting the postgres databaseport: 5432 //env var: PGPORTmax: 10 // max number of clients in the poolidleTimeoutMillis: 30000 // how long a client is allowed to remain idle before being closed;//this initializes a connection pool//it will keep idle connections open for a 30 seconds//and set a limit of maximum 10 idle clientsvar pool = config;// to run a query we can acquire a client from the pool,// run a query on the client, and then return the client to the poolpool;pool
node-postgres uses pg-pool to manage pooling. It bundles it and exports it for convenience. If you want, you can
require('pg-pool') and use it directly - it's the same as the constructor exported at
It's highly recommended you read the documentation for pg-pool.
For more information about
config.ssl check TLS (SSL) of nodejs
To install the native bindings:
$ npm install pg pg-native
To use the native bindings, first install pg-native. Once pg-native is installed, simply replace
var pg = require('pg') with
var pg = require('pg').native. Make sure any exported constructors from
pg are from the native instance. Example:
However, currently some differences remain, especially :
codebut in the field
sqlState, and the name of a few other fields is different (see https://github.com/brianc/node-postgres/issues/938, https://github.com/brianc/node-postgres/issues/972). So for example, if you rely on error.code in your application, your will have to adapt your code to work with native bindings.
COPY TO/COPY FROM
node-postgres is by design pretty light on abstractions. These are some handy modules we've been using over the years to complete the picture. Entire list can be found on wiki
If you need help getting the tests running locally or have any questions about the code when working on a patch please feel free to email me or gchat me.
I will happily accept your pull request if it:
Information about the testing processes is in the wiki.
Open source belongs to all of us, and we're all invited to participate!
If at all possible when you open an issue please provide
Usually I'll pop the code into the repo as a test. Hopefully the test fails. Then I make the test pass. Then everyone's happy!
If you need help or run into any issues getting node-postgres to work on your system please report a bug or contact me directly. I am usually available via google-talk at my github account public email address. Remember this is a labor of love, and though I try to get back to everything sometimes life takes priority, and I might take a while. It helps if you use nice code formatting in your issue, search for existing answers before posting, and come back and close out the issue if you figure out a solution. The easier you can make it for me, the quicker I'll try and respond to you!
If you need deeper support, have application specific questions, would like to sponsor development, or want consulting around node & postgres please send me an email, I'm always happy to discuss!
I usually tweet about any important status updates or changes to node-postgres on twitter. Follow me @briancarlson to keep up to date.
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