An introduction to CouchDB

Transcript

1. !"
2. ! I'M JULIA
4. WEB DEVELOPER @ NEIGHBOURHOODIE SOFTWARE
5. !"
6. ON-CALL HORROR STORIES (OF MY FRIENDS) > Database Server going offline (panic!) > Failed attempt in scaling up causes corrupted & lost data I realised that CouchDB has some distinct features that I just took for granted
7. Apache CouchDB has started. Time to relax.
8. !" RELAX
9. RELAX? > ease of use JSON & HTTP ! works with all* Languages
10. RELAX? > fault-tolerant > build with anticipating failure > Couch = cluster of unreliable commodity hardware Build with Erlang
11. ERLANG robust & concurrent > developed for real-time telecom applications > extreme emphasis on reliability and availability
12. DOCUMENT DATABASE
13. DOCUMENT DATABASE ! > JSON > unique IDs > schema-free > attachments
14. COUCHDB DOCUMENT { "_id": "00001", "_rev": "1-A", "name": "Bulbasaur", "types": ["grass", "poison"], "abilities": ["Overgrow","Chlorophyll"], "catch_rate": 45 }
15. QUERYING
16. QUERYING > Map/Reduce > Mango > Primary Index > changes
17. MAP/REDUCE > runs func on every doc in the db (once!) this creates a view index (b-tree) > next time of query -> only runs on docs that have changed/are new
18. MAP > Creates index function myMapFunction(doc) { emit(doc.name); } > Query The index
19. REDUCE Already Build in: '_sum', '_count', '_stats' { map: function (doc) { emit(doc.name.charAt(0)); }, reduce: '_count' }
20. MANGO a DSL inspired by MongoDB > faster-performing & easier to use > ! since CouchDB 2.0.0
21. MANGO { selector: { name: { $eq: 'Pikachu' } } }
22. PRIMARY INDEX curl -X GET 127.0.0.1:5984/pokemon/00025 > Index by ID > Already there > super fast ! create your own IDs in a clever format
23. MAKE USE OF THE PRIMARY INDEX Example: Timeseries Data (Logs) > system has many devices > device sends log data ID Format: system:device:ISODate
24. MAKE USE OF THE PRIMARY INDEX Example: Timeseries Data (Logs) // get all logs of Device 1 of System 23 from January 2017, latest first await db.allDocs({ include_docs: true, startkey: `system23:device1:2017-01-`, endkey: `system23:device1:2017-01-\uffff`, descending: true })
25. REAL-TIME CHANGE NOTIFICATIONS > index by sequence /db/_changes > What changes happened in die database? > What change occurred to this document? > What changed since X?
26. REPLICATION CouchDB was designed with sync in mind, and this is exactly what it excels at.
27. REPLICATION { "_id": "00001", "_rev": "1-A", "name": "Bulbasaur", "types": ["grass", "poison"], "abilities": ["Overgrow","Chlorophyll"], "catch_rate": 45 }
28. REPLICATION { "_id": "00001", "_rev": "1-A", "name": "Bulbasaur", "types": ["grass", "poison"], "abilities": ["Overgrow","Chlorophyll"], "catch_rate": 45 } CouchDB requires you to manage revisions (_rev) (tedious but pays off in the end)
29. REPLICATION > MVCC (Multiversion concurrency control) > sequence index & revisions
30. REPLICATION > bi-directional replication (synchronization) > multi-primary architecture
31. REPLICATION ! ⬅ ☁☁☁ ↖ ☁☁☁ ↘ ☁☁ *
32. REPLICATION ! ⬅ ☁☁☁ ↖ ☁☁☁ ↘ ☁☁ * ↕ !
33. REPLICATION ! ⬅ ☁☁☁ ↖ ☁☁☁ ↘ ☁☁ * ! !
34. REPLICATION CONFLICTS > an arbitrary winner Revision is chosen by CouchDB > conflicting Revisions are also stored > no Data is lost > up to the application developer to decide what to do
35. COUCHDB 2.0 ( ! ! ) > (Amazon) Dynamo Paper > same API as Single Instance > ready for big data workloads
36. NEIGHBOURHOODIE SOFTWARE > CouchDB Consulting / Support / Workshops > ! Opservatory - CouchDB Monitoring > Greenkeeper - Javascript Dependency updates > (Offline-First) App Development Consulting
37. !
38. LINKS > CouchDB Docs > Offline-First Web App with Couch & Pouch Tutorial > Learn Mango Queries