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Introduction to NoSQL db and mongoDB

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This document provides an overview of MongoDB, including a comparison to traditional relational databases, MongoDB features and terminology, CRUD operations, indexing, replication, sharding, and aggregation. It also includes links to additional MongoDB resources for further learning.

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Introduction to NoSQL db and mongoDB
BIO Senior SW Engineer @RAI Radiotelevisione italiana Rome, Italy QUIT IT APP @quititapp GET IN TOUCH! roberto.belardo@gmail.com @robertobelardo robertobelardo.wordpress.com Skype: backslash451
Traditional RDBMS ACID (atomicity, Consistency, Isolation, Durability) Great for relation data widely adopted and well understood TRANSACTIONS JOINS
but ≒ ≒ ≒ ≒ joins are slow do not scale easily SQL is a pain in the ass -> ORM SCHema are not flexible - and -
NOSQL DB ONLY ≒ ≒ ≒ ≒ ACID-LESS (NOT ALWAYS SWEET) Elastic scaling Big data Flexible data models KEY/VALUE STORES memcached db project voldemort redis dynamo DOCUMENT DB mongo db couch base GRAPH STORES neo4j orient db allegro virtuoso wide column stores big table hbase accumulo cassandra
Introduction to NoSQL db and mongoDB
mongo features ≒ ≒ ≒ ≒ ≒ Schema-less bson document (binary json) full index support replication and high availability Easy to use
Jargon RDBMS mongoDB Table Collec=on Row(s) (JSON) Document Column Field Index Index Join Embedding & Linking Par==on Shard GROUP BY Aggrega=on
Data SNIPPET {_id: !ObjectId(4dfa6baa9c65dae09a4bbda5),! title: Programming in Scala,! author: [! !{! ! !first_name: ! !Martin,! ! !last_name: ! !Odersky,! ! !nationality: !DE,! ! !year_of_birth: !1958! !},! !{! ! !first_name: ! !Lex,! ! !last_name: ! !Spoon! !},! !{! ! !first_name: ! !Bill,! ! !last_name: ! !Venners! !}! ]}!
CRUD querying INSERT a document in a collec7on > db.foo.insert({name:Sauron, type:bad-ass, address:Mordor, eyes:1})! SELECT all documents in a collec7on > db.foo.find()! SELECT some documents in a collec7on > db.foo.find({eyes:1}) > db.foo.find({eyes:1, type:bad-ass})! UPDATE a document in a collec7on > db.foo.save({_id:10, name:Sauron, type:good boy})! > db.foo.update({type:bad-ass},{$inc:{eyes:1}},{multi:true})! DELETE all documents in a collec7on > db.foo.remove()! DELETE some documents in a collec7on > db.foo.remove({eyes:1})!
Advanced STUFF
WRITE CONCERNS Speci鍖es where a write (insert) opera3on has succeeded. In some failure cases, write opera3ons issued with weak write concerns may not persist. weak concern fast writes With stronger write concerns, clients wait aAer sending a write opera3on for MongoDB to con鍖rm the write opera3on. errors ignored w:-1 It does not acknowledge write op. and the client cannot detect failed write op. unacknowledged w:0 It does not acknowledge write op. but driver aUempt to handle network errors. acknowledged w:1 It con鍖rms the receipt of the write op. allowing clients to catch errors. journaled w:1,j:true It con鍖rms the receipt of the write op. only aWer commiXng the data to journal. replica acknowledged w:n (n>1) It con鍖rms the receipt of the write op. aWer acknowledging primary and n-足1 secondaries. DEFAULT
INDEXES Without indexes, mongoDB must scan every document in a collec3on! index types Default _ID single field compound index multikey index geospatial index text indexes hashed indexes properties unique indexes sparse indexes creating indexes > db.foo.ensureIndex({phone-number:1}) ! ! > db.foo.ensureIndex({name:1, phone-number:1})! ! > db.foo.ensureIndex({name:1}, {unique:true})! > db.foo.ensureIndex({nickname:1}, {sparse:true})! ! > db.foo.ensureIndex({a:1},{unique:true,sparse:true})!
REPLICAtion Replica3on provides redundancy and increases data availability. Automatic failover: ELECTIONS
SHARDING horizontal scaling the mongoway SHARDimmutable KEYs shard key is { range based sharding hash based sharding . easily divisible among shards . high degree of randomness . targets a single shard . compound shard key > db.runCommand({ shardcollection:test.users, ! ! ! ! ! !key: { email:1}})! split--ting triggered automatically by a mongos if a chunk goes beyond max size (default 64mb) Balanc ing triggered automatically by a mongos if there is a chunk imbalance (8+ chunks)
Aggre | gation MaP Reduce framework operators . filter . project . unwind . group . sort . limit > db.article.aggregate(! !{ $project: {author:1, tags: 1}},! !{ $unwind: $tags},! !{ $group: { !_id: $tags, ! ! ! ! !authors: { $addToSet: $author}}})! { result: !{_id: !{_id: !{_id: !{_id: !],! !ok:1! }! [! art, authors:[bill, bob]},! sports, authors:[jane, bob]},! food, authors:[jane, bob]},! science, authors:[jane, bob, bill]},!
still a lot to cover! map reduce geo spatial GRID FS drivers etc.
resources hBp://www.mongodb.org/ hBp://www.mongodb.com/learn/nosql hBp://www.mongodb.org/about/introduc7on/ hBp://try.mongodb.org/ hBp://www.slideshare.net/spacemonkeylabs/data-足as-足documents-足overview-足and-足intro-足 to-足mongodb ≒ hBps://speakerdeck.com/backslash451 ≒ hBps://educa7on.mongodb.com/ ≒ hBp://lmgQy.com/?q=mongoDB ≒ ≒ ≒ ≒ ≒

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Introduction to NoSQL db and mongoDB

  • 2. BIO Senior SW Engineer @RAI Radiotelevisione italiana Rome, Italy QUIT IT APP @quititapp GET IN TOUCH! roberto.belardo@gmail.com @robertobelardo robertobelardo.wordpress.com Skype: backslash451
  • 3. Traditional RDBMS ACID (atomicity, Consistency, Isolation, Durability) Great for relation data widely adopted and well understood TRANSACTIONS JOINS
  • 4. but ≒ ≒ ≒ ≒ joins are slow do not scale easily SQL is a pain in the ass -> ORM SCHema are not flexible - and -
  • 5. NOSQL DB ONLY ≒ ≒ ≒ ≒ ACID-LESS (NOT ALWAYS SWEET) Elastic scaling Big data Flexible data models KEY/VALUE STORES memcached db project voldemort redis dynamo DOCUMENT DB mongo db couch base GRAPH STORES neo4j orient db allegro virtuoso wide column stores big table hbase accumulo cassandra
  • 7. mongo features ≒ ≒ ≒ ≒ ≒ Schema-less bson document (binary json) full index support replication and high availability Easy to use
  • 8. Jargon RDBMS mongoDB Table Collec=on Row(s) (JSON) Document Column Field Index Index Join Embedding & Linking Par==on Shard GROUP BY Aggrega=on
  • 9. Data SNIPPET {_id: !ObjectId(4dfa6baa9c65dae09a4bbda5),! title: Programming in Scala,! author: [! !{! ! !first_name: ! !Martin,! ! !last_name: ! !Odersky,! ! !nationality: !DE,! ! !year_of_birth: !1958! !},! !{! ! !first_name: ! !Lex,! ! !last_name: ! !Spoon! !},! !{! ! !first_name: ! !Bill,! ! !last_name: ! !Venners! !}! ]}!
  • 10. CRUD querying INSERT a document in a collec7on > db.foo.insert({name:Sauron, type:bad-ass, address:Mordor, eyes:1})! SELECT all documents in a collec7on > db.foo.find()! SELECT some documents in a collec7on > db.foo.find({eyes:1}) > db.foo.find({eyes:1, type:bad-ass})! UPDATE a document in a collec7on > db.foo.save({_id:10, name:Sauron, type:good boy})! > db.foo.update({type:bad-ass},{$inc:{eyes:1}},{multi:true})! DELETE all documents in a collec7on > db.foo.remove()! DELETE some documents in a collec7on > db.foo.remove({eyes:1})!
  • 12. WRITE CONCERNS Speci鍖es where a write (insert) opera3on has succeeded. In some failure cases, write opera3ons issued with weak write concerns may not persist. weak concern fast writes With stronger write concerns, clients wait aAer sending a write opera3on for MongoDB to con鍖rm the write opera3on. errors ignored w:-1 It does not acknowledge write op. and the client cannot detect failed write op. unacknowledged w:0 It does not acknowledge write op. but driver aUempt to handle network errors. acknowledged w:1 It con鍖rms the receipt of the write op. allowing clients to catch errors. journaled w:1,j:true It con鍖rms the receipt of the write op. only aWer commiXng the data to journal. replica acknowledged w:n (n>1) It con鍖rms the receipt of the write op. aWer acknowledging primary and n-足1 secondaries. DEFAULT
  • 13. INDEXES Without indexes, mongoDB must scan every document in a collec3on! index types Default _ID single field compound index multikey index geospatial index text indexes hashed indexes properties unique indexes sparse indexes creating indexes > db.foo.ensureIndex({phone-number:1}) ! ! > db.foo.ensureIndex({name:1, phone-number:1})! ! > db.foo.ensureIndex({name:1}, {unique:true})! > db.foo.ensureIndex({nickname:1}, {sparse:true})! ! > db.foo.ensureIndex({a:1},{unique:true,sparse:true})!
  • 14. REPLICAtion Replica3on provides redundancy and increases data availability. Automatic failover: ELECTIONS
  • 15. SHARDING horizontal scaling the mongoway SHARDimmutable KEYs shard key is { range based sharding hash based sharding . easily divisible among shards . high degree of randomness . targets a single shard . compound shard key > db.runCommand({ shardcollection:test.users, ! ! ! ! ! !key: { email:1}})! split--ting triggered automatically by a mongos if a chunk goes beyond max size (default 64mb) Balanc ing triggered automatically by a mongos if there is a chunk imbalance (8+ chunks)
  • 16. Aggre | gation MaP Reduce framework operators . filter . project . unwind . group . sort . limit > db.article.aggregate(! !{ $project: {author:1, tags: 1}},! !{ $unwind: $tags},! !{ $group: { !_id: $tags, ! ! ! ! !authors: { $addToSet: $author}}})! { result: !{_id: !{_id: !{_id: !{_id: !],! !ok:1! }! [! art, authors:[bill, bob]},! sports, authors:[jane, bob]},! food, authors:[jane, bob]},! science, authors:[jane, bob, bill]},!
  • 17. still a lot to cover! map reduce geo spatial GRID FS drivers etc.
  • 18. resources hBp://www.mongodb.org/ hBp://www.mongodb.com/learn/nosql hBp://www.mongodb.org/about/introduc7on/ hBp://try.mongodb.org/ hBp://www.slideshare.net/spacemonkeylabs/data-足as-足documents-足overview-足and-足intro-足 to-足mongodb ≒ hBps://speakerdeck.com/backslash451 ≒ hBps://educa7on.mongodb.com/ ≒ hBp://lmgQy.com/?q=mongoDB ≒ ≒ ≒ ≒ ≒