https://stackoverflow.com/questions/22113990
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RussianIt's a very broad question to answer but I'll try to cover some of the key reasons for why Couchbase is fast and scalable.
Writes in Couchbase are by default asynchronous,replication and persistence happen in the background, and the smart clients (SKD's) are notified of success or failure. So basically any new documents or mutations to documents are written to ram and then asynchronously flushed to disk in the background and replicated to other nodes. This means that there is no waiting time or contention on IO/disk speed. (This means it is possible to write to ram and then the node to fall over before the request has been persisted to disk or replicated to a secondary/third node). It is possible to make writes synchronously but it will slow down throughput considerably.
When dealing with ram, writes and read are VERY fast (we've only pushed our cluster to 20k operations a second) but large companies easily hit upwards of 400k operations a second. LinkedIN sustain this ops rate with only 4 nodes ---> http://www.couchbase.com/customer-stories
In traditional database architectures usually the setup would be a master DB (Mysql/Postgres/Oracle) coupled with a slave DB for data redundancy, also writes/reads can be split between the 2 as load gets higher. Couchbase is meant to be used as a distributed system (Couchbase recommend at least 3 nodes in production). Data is automatically sharded between the nodes in a cluster thus spreading the writes/reads across multiple machines. In the case of needing higher throughput, adding a node in Couchbase is as simple as clicking add node and then rebalance cluster, the data will be automatically partitioned across the new cluster map.
So essentially writing/reading from ram with async disk persistence + distributed reads and writes == high throughput
Hope that helps!
