NoSQL Systems
Consequences of sharding
Query with joins
- Need a distributed join algorithm!
- They exist.
- Distributed relational databases have been studied for a long time.
- OK for getting parallelism on complex queries on very large data sets.
- Not consistently scalable.
Transactions
- Distributed transactions are doable: Two-phase commit
- But they are very slow.
- The only "affordable" transaction occurs when all the updates
go to one shard.
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