Quick overview of MongoDB

Here is the slides from the presentation I gave at the tech architecture meetup in cape town / codebridge - https://www.facebook.com/events/429242577096097/433182133368808/?notif_t=plan_mall_activity

Transcript

1. MongoDB A quick overview Brad - @darb – Dev/Ops manager, Motribe
2. Structure of my talk Context / How we are using MongoDB Terminology in MongoDB world Deployment / Growing The things that suck
3. What we do - 3 web apps, 1 MongoDB cluster ‧ Motribe - mobile social network • ±50k monthly active users ‧ JudgeMe – mxit social app • 1m signups in 45 days / 200k+ photo uploads • 0.5m - 3m pageviews/day ‧ MxPix – mxit photo sharing app • 200k+ signups in a week / 70k+ photo uploads • 0.5m – 1m page views/day
4. MongoDB (from "humongous") ‧ JSON Document storage ‧ Documents are members of Collections ‧ Collections belong to Databases ‧ Indexes on any key in a document ‧ Javascript interface for queries ‧ Trivial Sharding of data
5. Some benefits ‧ Implicit creation of databases, collections ‧ Index and query anything inside document (composite keys, 2d/geo indexing) ‧ Great documentation ‧ Great examples (e.g. randomization) ‧ Emphasis on Just Works™ ‧ Drivers in many languages ‧ Active community
6. Grow up or out ‧ Horizontal – read/write throughput • Shard databases - split collections over shards • Shard collections - split documents over shards ‧ Vertical – read throughput • Replica sets – Auto master / slaves, voting, promotion, demotion – Time delayed slaves – Magic... bring up mongo server, inform config server, siphons data
7. Moving parts at scale ‧ Routers – “mongos” • Abstract the magic, route requests to the right place • Collate responses from shards, etc. • Apps connect to “mongos” ‧ Config servers • Min 3x for redundancy • Knows about dbs, shards, slaves
8. A picture
9. Monitoring ‧ Mongo Monitoring Service (MMS) is lovely ‧ JS console means you can do powerful things on the terminal ‧ JS interface exposes lots of data • Size of indexes • Comprehensive info about where db/collections stored • Location, status and health of nodes
10. The things that suck ‧ Index anything means indexes can get large (e.g. we have 4gb of indexes on a big collection) ‧ You need to aim to have all indexes+data in ram ‧ MapReduce is available but meh • Improving with each release, possible to hack onto hadoop
11. More of the things that suck ‧ Implicit creation means mis-spelled dbs, collections == WTF ‧ B-tree indexes mean queries/insertion by _id are O(log n) not O(1) ala pure key/value stores