Presentation: NoSQL databases by Harry Kauhanen
Quite a few interesting slides in Harry Kauhanen’s presentation:
Slide 5: Key-value stores
- The value is a binary object aka “blob” — the DB does not understand it and does not want to understand it
Slide 7: Document databases
- Key-value store, but the vlaue is (usually) structured and “understood” by the DB
- Querying data is possible (by other means than just a key)
Slide 10: ide column stores
- “a sparse, distributed multi-dimensional sorted map”
Slide 12: Graph databases
- “Relational database is a collection of loosely connected tables” whereas “Graph database is a multi-relational graph”
Slide 14:
- Relationships in RDBMS are “weak”
- Relationships in graph databases are first class citizens
Slide 23: Why NoSQL?
- Schema-free
- Massive data stores
- Scalability
- Some services simpler to implement than using RDBMS
- Great fit for many “Web 2.0” services
Slide 24: Why NOT NoSQL?
- RDBMS and tools are mature
- NoSQL implementations often “alpha”
- Data consistency, transactions
- “Don’t scale until you need it”
