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Distribution
Approaches
- B-Tree
- Supports range queries on totally ordered keys
- Allows several records from the same table to be returned with a single request.
- May cause a server to become a hot spot.Distribute table across many servers?
- Hashing
- Simple
- Likely to spread the load better
- If a single request needs multiple records from a table, it's likely to require separate requests to multiple servers, which adds overhead
- Is there any locality in interesting database applications?
- The most interesting form of locality is locality within a request: would like to satisfy each request with a single call to a single server, if possible.
B-Trees
- RP*
Hashing
- Extensible
- Linear
- Consistent
Replication
- Is replication needed for performance reasons?
- If a single server can handle 1M requests/second, is there any need to replicate?
- If the load gets too high, perhaps reduce the load by reducing the amount of data stored on a server, rather than replicating the data.
- If there is a hot spot, data reduction may not solve overloading problems.
- A system without replication would be much easier to manage
- Perhaps replicas are needed to reduce latency (e.g., East Coast datacenter and West Coast datacenter).
Locality
- Is there any locality in interesting database applications?
- The most interesting form of locality is locality within a request: would like to satisfy each request with a single call to a single server, if possible