Why we chose mongodb for guardian.co.uk

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Why we chose mongodb for guardian.co.uk

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  • \n\n
  • Theme: evolution of platform\nadapting to change is critical - will start with some history as to how we adapted to chg\n\n
  • \n
  • Ancient system\nScripts & database\nBespoke software, changes difficult\n
  • \n
  • Site oriented to broadcast publishing model\nCMS helps. No longer lashing things together \n\n
  • Template & rdbms oriented design, and TCL = no real domain model\nHeavyweight schema change process\n\n
  • This is from a TEMPLATE!\nscroll down to reveal HTML\n(about 10,000 of these)\n
  • bottom of template\nabout 10,000 of these!\n\n
  • Can’t change schema easily, to many dependencies in templates\n\n
  • dodo\ne.g. at start just articles; now video, interactives, audio, galleries, live blogs...\n
  • \n
  • “Web 2.0”, community, RSS, discoverability, tagging.\n\n
  • Very standard 3 tier application\nScale application servers on load\nCaching local to application server at first. Memcached added later\nRead heavy, broadcast model. Almost no writes compared to reads\n\n
  • Very standard 3 tier application\nScale application servers on load\nCaching local to application server at first. Memcached added later (in next era!)\nRead heavy, broadcast model. Almost no writes compared to reads\n\n
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  • \n
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  • \n
  • Talk: beginning to use NoSql in real organisation. Change in journalism affecting platform\n\n
  • We don’t have a scale problem with current application & model\n(Interesting fact: small dip at end is actually period of very high load. Caching works)\n\n
  • Talk: beginning to use NoSql in real organisation. Change in journalism affecting platform\n\n
  • Most of our new features - and partners - drive from the content api\n
  • Introduction of memcached & Solr\nSolr hosted in the cloud (EC2)\n
  • “Out” service\n
  • \n
  • Most recent content\n\n
  • Most recent content with tags, fields\n(this is pretty well how we went live with the content api)\n\n\n
  • Single article with media\nExtensible schema, eg: adding geotagging to images. Hard in DB, easy in JSON\nThis document represents at least 30 database tables!\n\n\n
  • \n\n
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  • Couch used at BBC. To simple.\nCassandra: Impressive. Do we need it? Schema design tricky.\nMongoDB: Not a huge mindset change. Devs working in a few days\n
  • Not a million miles from a RDBMS\nSimpler\n
  • Experiments with mongodb & content API\nGuardian site categorises content with tags\nTone tag represents “editorial tone” of content\n(SKIP IF LESS THAN 10 MINS TO GO!)\n\n
  • Different tag types can have different schemas\nKeywords (subjects) are in a section, music / madonna\n\n
  • \n\n
  • \n\n
  • \n\n
  • Suppose we want to add external musicbrainz ID to tag?\nAn update can modify the schema at runtime. No downtime.\n\n
  • Where clause: id\n$push atomically ads external reference onto tag\n\n
  • Resulting document now looks like this\n\n
  • Migration project, not green fields\n
  • REST API\nMapped initially just to oracle, then (next slide) to both datastores\nIntegration tested\n\n
  • API supports both data stores - lazy migration\nCurrently writing this - so far 60-70% less code for mongo version\n\n
  • Then batch migration and bye bye oracle\n
  • In the future?\n\n
  • \n\n
  • \n\n
  • Why we chose mongodb for guardian.co.uk

    1. Why we chose mongodbfor guardian.co.uk Graham TackleyWeb Platform Team Lead, guardian.co.uk
    2. “It is not the strongest of the species thatsurvives, nor the most intelligent. It is the one that is most adaptable to change.”
    3. Early Period circa ’95The “Lash It Together” era
    4. Early Period (95, the “Lash It Together” era) Perl, CGI, apache ExperimentalManual processesBespoke software RDBMS, scripts & static files
    5. Mid Period circa ’00The “Vendor CMS” era
    6. Mid Period: 2000s (The “Vendor CMS era”) Vignette / AOLserver TCL, Apache, Oracle Platform for online publishingInitially scales well withacceleration in delivery of features
    7. Mid Period: 2000s (The “Vendor CMS era”) Surprise! Vendor’s CMSdoesn’t do what we want! Mish-mash in templates: HTML, JavaScript, TCL, SQL, PL-SQLNo model in app tier, onlyin RDBMS schema created in Oracle Designer
    8. Mid Period: 2000s (The “Vendor CMS era”)
    9. Mid Period: 2000s (The “Vendor CMS era”)
    10. Mid Period: 2000s (The “Vendor CMS era”)After a few years, very difficult to extend Database schemabecomes fixed due to dependencies in templates
    11. Mid Period: 2000s (The “Vendor CMS era”)If you can’t change the system:
    12. Modern Period circa ’05-09The “J2EE Monolithic” era
    13. Web server Web server Web server I bring you NEWS!!!App server App server App server Oracle CMS Data feeds
    14. Web server Web server Web server Modern java app I bring you NEWS!!!App server App server App server Spring / Hibernate DDD / TDD Strong Oracle in java model Database abstracted away with ORM CMS Data feeds
    15. Problems
    16. Each release involves schema upgradeSchema upgrade = downtime for journalists
    17. Complexity still increasing: 300+ tables, 10,000 lines of hibernate XML config1,000 domain objects mapped to database 70,000 lines of domain object code Very tight binding to database
    18. ORM not really masking complexity: Database has strong influence on domain model: manydomain objects made more complex mapping joins in RDBMSComplex hibernate features used, interceptors, proxies Complex caching strategy Lots of optimisations And:We still hand code complex queries in SQL!
    19. Load becoming an issueRDBMS difficult to scale
    20. Partial NoSQL circa ’09-10The “Sticking Plaster” era
    21. Introduce yet more caching to patch up load problems Text Introduction of memcached
    22. Decouple applications from database by building APIsPower APIs using alternative, more scalable technologies APIs used to scale out database reads Writes still go to RDBMs
    23. Content APIMutualised news! http://content.guardianapis.com Read API delivered using Apache Solr Hosted in EC2 Document oriented search engine Scales well for read operations
    24. Core Api Web servers Solr/API App server Solr/APIMemcached (20Gb) Solr/API rdbms Solr Solr/API Solr/API CMS Cloud, EC2
    25. Mutualised news!We’ve solved our load problem (for now) but Increased our complexity
    26. Mutualised news! We now have 3 models! RDBMS tables Java Objects JSON API
    27. Mutualised news!
    28. Mutualised news!
    29. Mutualised news!
    30. MutualisedAPI is very simple JSON news!Multiple domain concepts expressed in single document Can be designed in forwardly extensible wayWhat if the JSON API was our primary model?
    31. Full NoSQL in developmentThe “It’s the future!” era
    32. Database selection Simple keystore. Too simple? Huge scalability. Do we need it? Schema design difficult. Simple to use, can execute similar queries to RDBMs
    33. MongoDB Mutualised news! database Document oriented Stores parsed JSON documents Can express complex queries Can be flexible about consistencyMalleable schema: can easily change at runtime Can work at both large & small scales
    34. Flexible SchemaMutualised news!
    35. Flexible SchemaMutualised news!
    36. Flexible SchemaMutualised news!Can easily represent different classes of tag as documents Both documents can be inserted into same collection Far simpler than equivalent hibernate mapped subclass configuration
    37. Flexible Schema Simple to query:Mutualised news!
    38. Flexible Schema Simple to query:Mutualised news! Query operators: $ne, $nin, $all, $exists, $gt, $lt, $gte ...
    39. Modifying the schemaMutualised news!
    40. Modifying the schemaMutualised news!
    41. Modifying the schemaMutualised news!
    42. The first project: IdentityCurrent login/registration system still in TCL/PL-SQL 3M+ users in relational database Very complex schema + PL-SQL New system required Can we migrate from Oracle to NoSql?
    43. Build API that can support both backends Registration app guardian.co.uk API This bit is hard! Oracle
    44. Build API that can support both backends Registration app guardian.co.uk API MongoDB Oracle
    45. Migrate using API & decommision Registration app guardian.co.uk API MongoDB
    46. Add new stuff! Registration app guardian.co.uk APIMongoDB Solr? Redis?
    47. MongoDBSimple, flexible schema with similar query & indexing to RDBMS Great at small or large scale Easy for developers to get going Commercial support available (10Gen) One day may power all of guardian.co.ukNo transactions / joins: developers must cater for thisProduces a net reduction in lines of code / complexity
    48. Shameless plugs http://content.guardianapis.com We’re hiring: http://www.gnmcareers.co.uk ref JS323graham.tackley@guardian.co.uk - @tackers

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