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A COMMAND PROMPT TALK. Node.js and postgres. An Introductory Glance With Live Code, Later. 2010 AURYNN SHAW, COMMAND PROMPT INC. Hi!. What is Node.js. Fast Pure event-driven server-side javascript programming environment. Ew, javascript. Built on Google’s V8

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Node js and postgres
Node.js and postgres

  • An Introductory Glance

  • With Live Code, Later

2010 AURYNN SHAW, COMMAND PROMPT INC.



What is node js
What is Node.js

  • Fast

  • Pure event-driven

  • server-side

  • javascript programming environment


Ew javascript
Ew, javascript

  • Built on Google’s V8

  • Runs on modern unix-likes (Linux, OSX, Freebsd, Cygwin)

  • Speaks network natively, and easily (Hello world is in http!)

  • Ends up Similar to Python, Perl, Ruby, ETc.


Did i mention fast
Did I mention fast?

  • Single thread can do many thousands of connections

  • standard library doesn’t block


Did i mention fast1
Did I mention fast?

  • Single thread can do many thousands of connections

  • standard library doesn’t block

  • Keeps the slow tasks from blocking

  • Keeps the quick tasks quick


Blocking
blocking?

# Standard synchronous processing

fh = open(“somefile”,”r”)

contents = fh.read()

# what if somefile is huge, 1GB+ ?

print contents




Did i mention fast2
Did I mention fast?

  • Single thread can do many thousands of connections

  • standard library doesn’t block

  • Keeps the slow tasks from blocking

  • Keeps the quick tasks quick




Non blocking
Non-blocking!

fs.open(“somefile”, function (fd) {

// When the file descriptor gets returned.

var buffer = null;

fs.read(fd, buffer, length, position, function (e, bytes) {

// bytes read are here.

// buffer will be not-null.

});

});



Some caveats
Some caveats

  • node is entirely single-threaded

  • Event-driven programming is *really* different


A maze of callbacks
A maze of callbacks

fs.open(“/tmp/hello”, function (fd) {

var buffer = null;

fs.read(fd, buffer, length, position, function (e, bytes) {

// bytes read are here.

// buffer will be not-null.

});

});


Some caveats1
Some caveats

  • node is entirely single-threaded

  • Event-driven programming is *really* different

  • Javascript’s prototype model is also really different

  • The syntax has warts


Build a bridge out of her
Build a bridge out of her?

/*

This allows you to kind of inherit properly.

*/

var o = function () {};

var p = function () {

/* Because ‘this’ changes */

var self = this;

o.call(this);

};

p.prototype = o;

p.prototype.constructor = p;



Why is it important
Why is it important?

  • Javascript owns the frontend


Why is it important1
Why is it important?

  • Javascript owns the frontend

  • More jquery and javascript programmers every day


Why is it important2
Why is it important?

  • Javascript owns the frontend

  • More jquery and javascript programmers every day

  • Javascript is fast




When i got here
When I got here...

  • postgres.js worked.


When i got here1
When I got here...

  • postgres.js worked.

  • Used the simple query protocol


When i got here2
When I got here...

  • postgres.js worked.

  • Used the simple query protocol

  • Used SQL escape to prevent injection attacks.


Whyyyy
whyyyy

SOURCE: http://www.flickr.com/photos/striatic/2192192956/


But it did work
But it did work!






To prepare a query
to prepare a query

  • postgres.js Didn’t use libpq.


SOURCE: http://www.flickr.com/photos/tanaka/2319325408/


To prepare a query1
to prepare a query

  • postgres.js Didn’t use libpq.

  • Speaks pure protocol


To prepare a query2
to prepare a query

  • postgres.js Didn’t use libpq.

  • Speaks pure protocol

  • ...So I had to learn the protocol.


Wax on wax off
Wax on, wax off

MONTAGE!



Complexity abounds
Complexity Abounds

  • Simple protocol sends one message to pg

  • Easy to queue, internally.


REALLY SIMPLE MESSAGE QUEUE

QUERY

QUERY

QUERY

QUERY

QUERY

QUERY

RESULTS


Really though
Really, though

  • Simple protocol sends one message to PG

  • Easy to queue, internally.

  • Prepared statements require at least 5

  • Parse, describe, execute, bind, flush


THIS TYPE OF QUEUE DOESN’T WORK

SYNC

EXECUTE

BIND

DESCRIBE

PARSE

QUERY

QUERY


And while all this is happening
And while all this is happening

  • You cannot block the main thread

  • And postgres expects a synchronous request/response

  • But it does give responses...


And while all this is happening1
And while all this is happening

  • You cannot block the main thread


And while all this is happening2
And while all this is happening

  • You cannot block the main thread

  • And postgres expects a synchronous request/response


And while all this is happening3
And while all this is happening

  • You cannot block the main thread

  • And postgres expects a synchronous request/response

  • But it does give responses...



KIND OF LIKE THIS

SIMPLE

PREPARED

GROUP

SIMPLE

SIMPLE

PREPARED

GROUP

SIMPLE

SIMPLE


So we never block waiting for the db
So we never block waiting for the DB





Using postgres js
Using postgres.js

/* Node setup */

var pg = require(“lib/postgres-pure.js”),

sys = require(“sys”);

var db = new pg.connect("pgsql://test:[email protected]:5432/template1");

/* We now have a working DB handle.

Or, we have an error. Either way.

*/


Using postgres js1
Using postgres.js

/* We now have a working DB handle. */

/* From here, we do: */

db.query(“select 1::int;”, function (err, rs) {

// Wait, a function?

console.log(sys.inspect(rs));

});



What s going on here
What’s going on here?

/* We now have a working DB handle. */

/* From here, we do: */

db.query(“select 1::int;”, function (err, rs) {

// Wait, a function?

console.log(sys.inspect(rs));

});


What you get
What you get

1

3

// A little while later

2


It s happening asynchronously
It’s happening asynchronously!

  • The function argument is what’s going to happen when the DB comes back

  • db.query returns immediately

  • and your app keeps on going!



Prepared queries
Prepared queries

/* Prepared queries work the same way */

db.prepare(“select ?::int as foobar;”, function (sth) {

sth.execute(1, function (err, rs) {

console.log(sys.inspect(rs));

});

sth.execute(2, function (err, rs) {

console.log(sys.inspect(rs));

});

});


Prepared queries1
Prepared queries

/* which will return */

[ { foobar: 1 } ]

[ { foobar: 2 } ]


Or this
Or this!

/*

This becomes a prepared statement behind the scenes

*/

db.query(“select ?::int as foobar;”,

1, // A single argument

function (err, rs) {

console.log(sys.inspect(rs));

});


It would return
It would return

[ { foobar: 1 } ]



Bad bad bad
Bad, bad, bad.

  • postgres.js is still very alpha.

  • Node API is in flux

  • Learning Node takes a while



Things that are pleasing
Things that are pleasing

  • clean, perl DBI-based API.

  • Official support from Command prompt

  • Performance!


Vroom
Vroom

[ananke:~/src/postgres-js] aurynn> time node benchmark.js 40000

[ { count: 40001 } ]

node benchmark.js 40000 18.85s user 2.75s system 87% cpu 24.602 total

Just over 2122 queries/second.



Shiny things
Shiny things!

  • Notify support


Pg notifications
PG notifications

/* Event-driven frameworks are ideal for this, and

the notification setup can be handled behind the

scenes.

*/

db.on(“<NOTIFYNAME>”, function (payload) {

// Do something useful as a result of

// the notification from PG

});



Shiny things1
Shiny things!

  • Notify support

  • Stability


Shiny things2
Shiny things!

  • Notify support

  • Stability

  • Better error handling


Shiny things3
Shiny things!

  • Notify support

  • Stability

  • Better error handling

  • More test cases


Shiny things4
Shiny things!

  • Notify support

  • Stability

  • Better error handling

  • More test cases

  • Better type coercion







Okay live code shout out ideas
Okay. LIVE CODE!Shout out ideas!


Https github com commandprompt postgres js

FORK IT, AND HELP!

UNSTABLE

https://github.com/commandprompt/postgres-js/

https://github.com/aurynn/postgres-js/

NOT QUITE AS UNSTABLE


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