Building Apps with MongoDB

Building Apps With Nate Abele IPC — 1 June 2010 Berlin

Me Former lead developer, CakePHP Lead developer, Lithium Twitter: @nateabele

“Alternative” databases? What’s the point? Relational databases » relational algebra » set theory ORM “impedance mismatch” Failed alternatives reinforced the status quo

What’s a document database? Composed of documents ...duh Each document is heterogenous, and may have a completely unique structure compared to other documents ...That’s pretty much it

Why Mongo? .org : “The best features of document databases, key-value stores, and relational databases.”

Mongo is... Fast Smart Scalable

Terminology Database » Database Table » Collection Row » Document

Common Tasks tags id MySQL name posts_tags id posts comments post_id id id tag_id title post_id slug author body email published body created created updated

Common Tasks id posts title slug MongoDB body published created updated comments author email body created tags

Common Tasks MongoDB { "_id" : ObjectId("4c03e856e258c2701930c091"), "title" : "Welcome to MongoDB", "slug" : "welcome-to-mongodb", "body" : "Today, we're gonna totally rock your world...", "published" : true, "created" : "Mon May 31 2010 12:48:22 GMT-0400 (EDT)", "updated" : "Mon May 31 2010 12:48:22 GMT-0400 (EDT)", "comments" : [ { "author" : "Bob", "email" : "bob@example.com", "body" : "My mind has been totally blown!", "created" : "Mon May 31 2010 12:48:22 GMT-0400 (EDT)" } ], "tags" : [ "databases", "MongoDB", "awesome" ] }

[...frantic hand-wringing ensues...]

[...pause, deep breath...]

Doing the “normal db” stuff How do I... ...do pattern-matching? db.posts.find({ "title" : /mongodb/i }) ...ﬁnd all posts tagged ‘MongoDB’? db.posts.find({ "tags" : "MongoDB" }) ...ﬁnd all Bob’s comments? db.posts.find({ "comments.email" : "bob@example.com" })

Doing the “normal db” stuff How do I... ...change Bob’s email? db.posts.update( { "comments.email": "bob@example.com" }, { $set : { "comments.$.email" : "robert@example.com" }} )

Querying $gt $all $gte $size $lt $exists $lte $type $ne $elemMatch $in $not $nin $where $mod

Querying dontTrust = db.people.find({ “age”: { $gt : 30 } }) awesome = db.posts.find({ “tags” : { $in : [‘MongoDB’, ‘awesome’] }}) todo = db.tasks.find({ “status” : { $nin : [ ‘In Progress’, ‘Completed‘ ]} })

Querying By arbitrary function: db.posts.find({ $where: function() { return this.hits % 2 == 0; }}) By grouping key: db.posts.group({ "key": { "hits": true }, "initial": { count: 0 }, "reduce": function(obj, prev) { prev.count++; } });

Querying By grouping function: db.photos.group({ keyf: function(o) { return { hits: Math.round(o.hits / 1000) }; }, "initial": { count: 0 }, "reduce": function(obj, prev) { prev.count++; } });

Grouping results [ { 'hits' => 0, 'count' => 5 }, { 'hits' => 1, 'count' => 4 }, { 'hits' => 2, 'count' => 7 }, ... ]

Map/reduce ...with apologies to John Nunemaker.

Map/reduce > db.items.insert({tags: ['dog', 'cat']}) > db.items.insert({tags: ['dog']}) > db.items.insert({tags: ['dog', 'mouse']}) > db.items.insert({tags: ['dog', 'mouse', 'hippo']}) > db.items.insert({tags: ['dog', 'mouse', 'hippo']}) > db.items.insert({tags: ['dog', 'hippo']})

Map/reduce > var map = function() { this.tags.forEach(function(t) { emit(t, {count: 1}); }); }

Map/reduce > var reduce = function(key, val) { var count = 0; for(var i = 0, len = val.length; i < len; i++) { count += val[i].count; } return { count: count }; }

Map/reduce > var result = db.items.mapReduce(map, reduce);

Map/reduce { "ok" : 1, "timeMillis" : 86, "result" : "tmp.mr.mapreduce_1273861517_683", "counts" : { "input" : 6, "emit" : 13, "output" : 4 } }

Map/reduce db["tmp.mr.mapreduce_1273861517_683"].find() { "_id" : "cat", "value" : { "count" : 1 } } { "_id" : "dog", "value" : { "count" : 6 } } { "_id" : "hippo", "value" : { "count" : 3 } } { "_id" : "mouse", "value" : { "count" : 3 } }

Atomic Operations Incrementing & decrementing: $inc: db.posts.update( { _id : new ObjectId("4c041e...30c093") }, { $inc : { "hits" : 1 }} ) db.posts.update( { _id : new ObjectId("4c041e...30c093") }, { $inc : { "hits" : -1 }} )

Atomic Operations Adding, updating & removing: $set & $unset: db.posts.update({}, { $set : { "hits" : 0 }}) db.posts.update({}, { $unset : { "hits" : 1 }})

Atomic Operations Array operations: $push[All], $pull[All], $addToSet & $pop: db.posts.update({ "tags": "MongoDB" }, { $push: { "tags" : "awesome" } }) db.posts.update({ "tags": "MySQL" }, { $pull: { "tags" : "awesome" } })

Atomic Operations Array operations: $push[All], $pull[All], $addToSet & $pop: db.queues.update( { _id : new ObjectId("4c041e...30c093") }, { $pop: { "operations" : 1 }} ) db.todos.update( { _id : new ObjectId("4c041e...30c093") }, { $pop: { "listItems" : -1 }} )

Indexes Slows write performance, but greatly improves reads For best results, index on what you query on Mongo likes to ﬁt its indexes in memory

Indexes db.users.ensureIndex({ “email”: 1 }) db.posts.ensureIndex({ “tags”: 1 }) db.posts.ensureIndex({ “created”: -1 }) db.posts.ensureIndex({ “tags”: 1, “created”: -1 })

Indexes “unique” / “dropDups”: ensure uniqueness “safe”: Make sure it worked. Else, panic. “name”: Mostly for troubleshooting “background”: Best. Performance. Panic. Button. Ever.

Indexes When in doubt, explain() { "cursor" : "BtreeCursor hits_1 multi", "indexBounds" : [ [{ "hits" : 0 }, { "hits" : 0 }], [{ "hits" : 1 }, { "hits" : 1 }] ], "nscanned" : 1, "nscannedObjects" : 1, "n" : 1, "millis" : 35, "allPlans" : [ { "cursor" : "BtreeCursor hits_1 multi", "indexBounds" : [ [{ "hits" : 0 }, { "hits" : 0 }], [{ "hits" : 1 }, { "hits" : 1 }] ] } ] }

Location, location, location

Location MongoDB makes location-aware apps stupid-simple First, add an index: db.places.ensureIndex({ location: “2d” }) Go to town: db.places.find({ location: { $near : [ 40.79870933724115, -73.7656099560547 ]} })

Location

Location db.places.find({ location: { $within : { $box : { [ [40.800788494123154, -73.85556051757814], [40.68008976560161, -74.04232809570314] ] });

Easy to get started Up and running on most systems in a half-dozen commands or less fewer http://try.mongodb.org/

Coming to a platform near you

Drupal for MongoDB http://drupal.org/project/mongodb D7: mongodb_cache: Store cache items in mongodb D7: mongodb_ﬁeld_storage: Store the ﬁelds in mongodb D7: mongodb_session: Store sessions in mongodb D6/D7: mongodb_watchdog: Store the watchdog messages in mongodb D6/D7: mongodb: support library for the other modules D7: mongodb_block: Store block information in mongodb. Very close to the core block API D7: mongodb_queue: DrupalQueueInterface implementation using mongodb http://sf2010.drupal.org/conference/sessions/mongodb-humongous-drupal

Even MORE Drupal Work to get listing API into core: http://drupal.org/node/780154 Experimental goodies to play with: http://drupalcode.org/viewvc/drupal/contributions/ sandbox/chx/dbtng_mongo_experimental/

Joomla! MongoDB helper library for Joomla! Branch of 1.6 development for alternative query builder Full MongoDB support most likely in 2.0

Lithium PHP framework MongoDB native support since 0.2 http://rad-dev.org/lithium/wiki Projects demonstrating MongoDB support: http://rad-dev.org/lithium_mongo/source http://rad-dev.org/lithium_blog/source

CakePHP framework MongoDB datasource http://github.com/ichikaway/mongoDB-Datasource Example article http://mark-story.com/posts/view/using-mongodb- with-cakephp

MongoDB Language Center http://www.mongodb.org/display/DOCS/Drivers

Community Resources http://www.mongodb.org/display/DOCS/ Community

Development Tracker http://jira.mongodb.org

MongoDB Cookbook http://cookbook.mongodb.org/

Thanks! { email: “nate.abele@gmail.com”, twitter: “@nateabele”, web: “http://lithify.me/”, slides: “http://www.slideshare.net/nateabele” }

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Building Apps with MongoDB

by Nate Abele

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