Dropping ACID with MongoDB

Who am I?

what is
?

Application
Perl
Apache
Linux

Application
Perl
Database
Apache
Linux

Application
Perl
Apache
Windows

Application
Perl
Apache
Linux

Application
The world's most
popular open source
database
Perl
Apache
Linux

Application
Perl
Apache
Linux
The world's most
advanced open source
database

databases
contain tables
contain rows

schema
databases
contain tables
contain rows

schema
databases
contain tables
contain rows
joins

Application
Perl
Apache
Linux

getting started

www.mongodb.org

cpan -i MongoDB

$conn = MongoDB::Connection->new;

$db = $conn->foo;

$db = $conn->foo;
NO ADMINISTRATION

$db = $conn->foo;
$table = $db->bar;

server

server
databases

server
databases
contain tables

server
databases
collections
contain tables

server
databases
collections
contain tables
contain rows

server
databases
collections
contain tables
documents
contain rows

server
schema
databases
collections
contain tables
documents
contain rows

server
schema
databases
collections
contain tables
documents
contain rows
joins

server
databases
contain collections
contain documents

$db = $conn->foo;
$collection = $db->bar;

$db = $conn->foo;
NO ADMINISTRATION

$db = $conn->foo
$doc = {"name" => "kristina",
"contact info" => {
"twitter" => "@kchodorow",
"email" => "kristina@10gen.com"
},
"friends" => 400232,
"pic" => $file_str,
"member since" => DateTime->now};

$db = $conn->foo
$doc = {"name" => "kristina",
"contact info" => {
"twitter" => "@kchodorow",
"email" => "kristina@10gen.com"
},
"friends" => 400232,
"pic" => $file_str,
"member since" => DateTime->now};
$collection->insert($doc);

mongo is type-sensitive
and type-rich

null
boolean
integer
double
string
array
hash
qr/fobar/i
$bindata
DateTime
MongoDB::OID
MongoDB::Code
MongoDB::MinKey
MongoDB::MaxKey

$collection->find_one({
"name" => "kristina"});

"contact.twitter" => "@kchodorow"});

$collection->find({
"member since" => {
'$gt' => $yesterday,
'$lt' => $now
}});

$collection->find({
"member since" => {
'$lt' => $now
}})->sort({"friends" => 1});

$collection->find({
"member since" => {
'$lt' => $now
}})->sort({"friends" => 1})->limit(10);

$collection->find({
"member since" => {
'$lt' => $now
}})->sort({"friends" => 1})->limit(10)
->skip(100);

$cursor = $collection->find({
"member since" => {
'$lt' => $now
}})->sort({"friends" => 1})->limit(10)
->skip(100);

while (my $doc = $cursor->next) {
# ...
}
my @results = $cursor->all;

x < 3
{"x" => {'$lt' => 3}}

$gt
$lte
$ne
$mod
$exists
$type
...

$collection->update(
{"name" => "kristina"},

{'$set' =>

{'$set' =>
{"contact.website" =>
"snailinaturtleneck.com"
}});

updates are...
atomic
in-place (when possible)
able to create and delete fields
able to create documents

{"url" => "example.com"},
{'$inc' => {"pageviews" => 1}},
{"upsert" => 1}
);

$set
$inc
$push
$pop
$pull
...

"$gte"

"<null>"

'$gte' or "$gte"

Or define your own!
":gte"
"=gte"
"?gte"

Or define your own!
" gte"

Or define your own!
" gte"
" ♕ gte"

Or define your own!
" gte"
" ♕ gte"
"xgte"

features

I suddenly have a deep love for stored procedures

I suddenly have a deep love for stored procedures
now with stored procedures!

$db->system->js->insert({
"_id" => "x",
"value" => 3});
"_id" => "y",
"value" => 4});
$db->eval("return x+y");

my $log = <<<LOG
function(msg, level) {
var date = "[" + new Date() + "] ";
varlvl = level ? level+" " : "";
print(date + lvl + msg);
}
LOG;
"_id" => "log",
"value" => $log});

$db->eval("log('all your base are
belong to us', 'FATAL');");

$db->eval("log('all your base are
belong to us', 'FATAL');");
[Fri May 19 18:34:57] FATAL all your
base are belong to us

J
J
J
J
J
J
J
J
J

$metadata = {
"_id" => " "
"date" => DateTime->now
"downloads" => 0,
"user" => $userId,
"filename" => "rickroll.flv"
}
J

$grid = $db->get_gridfs;
$grid->put($fh, $metadata);

$file = $grid->find_one({
"filename" => qr/rickroll/i
});

$file = $grid->find_one({
"filename" => qr/rickroll/i
});
$file->print($fh2);

Benefits:
Automatic backups
Unlimited metadata
Millions of files per directory
Random access
Better disk locality

Geospatial Indexes

$coll->insert({location => (-40, 78)});

$coll->find({location => {
'$near' => (-40, 77)}})

$coll->find({location => {
'$near' => (-40, 77)}})->limit(10)

what doesn't it have?

transactions

are you practicing safe
data storage?

Insert this.
Okay, got it.
Phew, my data's safe.

Write this to disk
I know better than he does, I'll just let this sit in a buffer for a while.
All over it!

?
I have no idea what you're talking about.

trust no one!
...trust a bunch of ones. Mostly.

prod1.example.com
prod2.example.com

prod2.example.com
prod1.example.com

prod1.example.com
prod2.example.com

prod1.example.com
?
prod2.example.com

prod1.example.com
prod2.example.com

?
prod1.example.com
prod2.example.com

prod1.example.com
prod2.example.com

primary
secondary
secondary
passive

make sure two slaves have this

all set

EXCEPTION

$conn->w(3);
$collection->insert({"x" => 1},
{"safe" => 1});

scaling

sometimes read-only

sometimes read-only
sometimes inconsistent

U - Z
K - O
A - E
F - J
P - T

mongod
mongod
mongod
config
mongos

mongod
mongod
mongod
mongos
I want posts from April 2009 - June 2009

mongod
mongod
mongod
April and May is on #2. June is on #3.
mongos

mongod
mongod
mongod
mongos

mongod
mongod
mongod
mongos
Add this post for
March 26, 2010.

mongod
mongod
mongod
#3 hold June 2009-present
mongos

mongod
mongod
mongod
config
So, what's going on?
mongos

mongod
mongod
mongod
config
mongos

# ...

try.mongodb.org

www.mongodb.org

thank you!
@kchodorow
http://www.snailinaturtleneck.com

Dropping ACID with MongoDB

by kchodorow on Jun 23, 2010

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