Consistency
- Tags
- sys-design
Refers to the consistency part of CAP.
Weak Consistency
After a write, reads may or may not see it. A best effort approach is taken.
Works well in real time cases such as video-chat, real-time multiplayer-games. For example if you lose connection in the middle of a phone call you don't hear the lost speech after a connection is re-established.
Eventual Consistency
After a write, reads will eventually see it (typically within ms). Data is
replicated asynchronously.
This approach works well in highly available systems (eg. DNS or email).
Strong Consistency
After a write, reads will see it. Data is replicated synchronously.
This approach is seen in file systems and RDBMSes. Strong consistency works well in systems that need transactions.