Mongo db php_shaken_not_stirred_joomlafrappe

PHP & MongoDB
Shaken, not stirred
Spyros Passas / @spassas
Friday, April 12, 13

NoSQL | Everybody is talking about it!

NoSQL | What
• NoSQL ≠ SQL is dead
• Not an opposite, but an alternative/complement to SQL (Not Only SQL)
• Came as a need for large volumes of data and high transaction rates
• Are generally based on key/value store
• Are very happy with denormalized data since they have no joins

NoSQL | Why
• Flexible Data Model, so no prototyping is needed
• Scaling out instead of Scaling up
• Performance is significantly higher
• Cheaper licenses (or free)
• Runs on commodity hardware
• Caching layer already there
• Data variety

NoSQL | Why not
• well, it’s not all ACID...
• Less mature than the relational systems (so the ecosystem of tools/addons
is still small)
• BI & Reporting is limited
• Coarse grained Security settings

NoSQL | Which
• Key/Value stores
• Document Databases
• And more...

MongoDB | Documents & Collections
• Document is the equivalent of an SQL table row and is a set of key/value
pairs
• Collection is the equivalent of an SQL table and is a set of documents not
necessarily of the same type
• Database is the equivalent of a... database
{
“name” : “Spyros Passas”,
“company” : “Neybox”
}
{
“company” : “Neybox”
}
{
“Event” : “JoomlaFrappe”,
“location” : “Athens”
}

MongoDB | What can a value be?
• Keys are always strings (without . and $)
• Value can be
• String
• Number
• Date
• Array
• Document
{“name” : “Spyros Passas”}
{“age” : 30}
{“birthday” : Date(“1982-12-12”}
{“interests” : [“Programming”, “NoSQL”]}
{“address” : {
“street” : “123 Pireus st.”,
“city” : “Athens”,
“zip_code” : 17121
}
}

MongoDB | Example of a document
{
“_id” : ObjectId(“47cc67093475061e3d95369d”),
“birthday” : Date(“1982-12-12”),
“age” : 30,
“interests” : [“Programming”, “NoSQL”],
“address” : {
“street” : “123 Pireus st.”,
“city” : “Athens”,
“zip_code” : 17121
}
“_id” : ObjectId(“47cc67093475061e3d95369d”)
ObjectId is a special type

MongoDB | Indexes
• Any field can be indexed
• Indexes are ordered
• Indexes can be unique
• Compound indexes are possible (and in fact very useful)
• Can be created or dropped at anytime
• Indexes have a large size and an insertion overhead

MongoDB | Operators & Modifiers
• Comparison: $lt (<), $lte (<=), $ne (!=), $gte (>=), $gt (>)
• Logical: $and, $or, $not, $nor
• Array: $all, $in, $nin
• Geospatial: $geoWithin, $geoIntersects, $near, $nearSphere
• Fields: $inc, $rename, $set, $unset
• Array: $pop, $pull, $push, $addToSet

MongoDB | Data Relations
• MongoDB has no joins (but you can fake them in the application level)
• MongoDB supports nested data (and it’s a pretty good idea actually!)
• Collections are not necessary, but greatly help data organization and
performance

MongoDB | Going from relational to NoSQL
• Rethink your data and select a proper database
• Rethink the relationships between your data
• Rethink your query access patterns to create eﬃcient indexes
• Get to know your NoSQL database (and its limitations)
• Move logic from data to application layer (but be careful)

MongoDB | Deployment
Mongo Server
Data Layer
Application Layer
App Server + mongos

MongoDB | Deployment
Mongo Server

MongoDB | Replica Set
Primary (Master)
Secondary (Slave)

MongoDB | Replica Set
Primary (Master)
Secondary (Slave)Secondary (Slave) Secondary (Slave)

MongoDB | Replica Set when things go wrong
Primary (Master)
Secondary (Slave)Secondary (Slave) Secondary (Slave)

Primary (Master)
Secondary (Slave) Secondary (Slave)

Primary (Master)
Secondary (Slave) Secondary (Slave)Secondary (Slave)

MongoDB | Replica set tips
• Physical machines should be in independent availability zones
• Selecting to read from slaves significantly increases performance (but you
have to be cautious)

MongoDB | Sharding
A...Z

MongoDB | Sharding
A...J K....P Q....Z

MongoDB | Sharding with replica sets
A...J K....P Q....Z
Replica SetReplica SetReplica Set

MongoDB | Sharding with replica sets
A...J K....P Q....Z
Config Servers
Replica SetReplica SetReplica Set

MongoDB | Things to consider when sharding
• Picking the right sharding key is of paramount importance!
• Rule of thumb:“the shard key must distribute reads and writes and keep the
data you’re using together”
• Key must be of high cardinality
• Key must not be monotonically ascending to infinity
• Key must not be random
• A good idea is a coarsely ascending field + a field you query a lot

MongoDB | PHP | The driver
• Serializes objects to BSON
• Uses exceptions to handle errors
• Core classes
• MongoClient: Creates and manages DB connections
• MongoDB: Interact with a database
• MongoCollection: Represents and manages a collection
• MongoCursor: Used to iterate through query results

MongoDB | PHP | MongoClient
<?php
// Gets the client
$mongo = new MongoClient(“mongodb://localhost:27017”);
// Sets the read preferences (Primary only or primary & secondary)
$mongo->setReadPreference(MongoClient::RP_SECONDARY);
// If in replica set, returns hosts status
$hosts_array = mongo->getHosts();
// Returns an array with the database names
$db_array = $mongo->listDBs();
// Returns a MongoDB object
$database = $mongo->selectDB(“myblog”);
?>
Creates a connection and sets read preferences
Provide info about hosts status and health
Lists, selects or drops databases

MongoDB | PHP | MongoDB
<?php
// Create a collection
$database->createCollection(“blogposts”);
// Select a collection
$blogCollection = $database->selectCollection(“blogposts”);
// Drop a collection
$database->dropCollection(“blogposts”)
?>
Handles Collections

MongoDB | PHP | MongoCollection | Insert
<?php
// Fire and forget insertion
$properties = array(“author”=>”spassas”, “title”=>”Hello World”);
$collection->insert($properties);
?>
Insert
<?php
// Safe insertion
$properties = array(“author”=>”spassas”, “title”=>”Hello World”);
$collection->insert($properties, array(“safe”=>true));
?>

MongoDB | PHP | MongoCollection | Update
<?php
// Update
$c->insert(array("firstname" => "Spyros", "lastname" => "Passas" ));
$newdata = array('$set' => array("address" => "123 Pireos st"));
$c->update(array("firstname" => "Spyros"), $newdata);
// Upsert
$c->update(
    array("uri" => "/summer_pics"),
    array('$inc' => array("page_hits" => 1)),
    array("upsert" => true)
);
?>

MongoDB | PHP | MongoCollection | Delete
<?php
// Delete parameters
$keyValue = array(“name” => “Spyros”);
// Safe remove
$collection->remove($keyValue, array('safe' => true));
// Fire and forget remove
$collection->remove($keyValue);
?>

MongoDB | PHP | MongoCollection | Query
<?php
// Get the collection
$posts = $mongo->selectDB(“blog”)->selectCollection(“posts”);
// Find one
$post = $posts->findOne(array('author' => 'john'), array('title'));
// Find many
$allPosts = $posts->find(array('author' => 'john'));
// Find using operators
$commentedPosts = $posts->find(array(‘comment_count’ => array(‘$gt’=>1)));
// Find in arrays
$tags = array(‘technology’, ‘nosql’);
// Find any
$postsWithAnyTag = $posts->find(array('tags' => array('$in' => $tags)));
// Find all
$postsWithAllTags = $posts->find(array('tags' => array('$all' => $tags)));
?>

MongoDB | PHP | MongoCursor
<?php
// Iterate through results
$results = $collection->find();
foreach ($results as $result) {
// Do something here
}
// Sort
$posts = $posts->sort(array('created_at'=> -1));
// Skip a number of results
$posts = $posts->skip(5);
// Limit the number of results
$posts = $posts->limit(10);
// Chaining
$posts->sort(array('created_at'=> -1))->skip(5)->limit(10);
?>

MongoDB | PHP | Query monitoring & Optimization
explain()
Gives data about index performance for a specific query
{
"n" : <num>, /* Number documents that match the query */
"nscannedObjects" : <num>, /* total number of documents scanned during
the query */
"nscanned" : <num>, /* total number of documents and index entries */
"millis" : <num>, /* time to complete the query in milliseconds */
“millisShardTotal” : <num> /* total time to complete the query on shards
*/
“millisShardAvg” : <num> /* average time to complete the query on each
shard */
}

Thank you!
{“status” : “over and out”,
“mood” : “:)”,
“coming_up” : “Q & A”
“contact_details”: {
“email”:“sp@neybox.com”,
“twitter”:”@spassas”,
}
}

Mongo db php_shaken_not_stirred_joomlafrappe

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