Using etcd as primary store/database?

Question

Can etcd be used as reliable database replacement? Since it is distributed and stores key/value pairs in a persistent way, it would be a great alternative nosql database. In addition, it has a great API. Can someone explain why this is not a thing?

Answer 1

etcd

• etcd is a highly available key-value store which Kubernetes uses for persistent storage of all of its objects like deployment, pod, service information.
• etcd has high access control, that it can be accessed only using API in master node. Nodes in the cluster other than master do not have access to etcd store.

nosql database

• There are currently more than than 255 nosql databases, which can be broadly classified into Key-Value based, Column based, Document based and Graph based. Considering etcd as an key-value store, lets see the available nosql key-value data stores.

• Redis, memcached and memcacheDB are popular key-value stores. These are general-purpose distributed memory caching system often used to speed up dynamic database-driven websites by caching data and objects in memory.

Why etcd not an alternative

• etcd cannot be stored in memory(ram) they can only be persisted in disk storage, whereas redis can be cached in ram and can also be persisted in disk.

• etcd does not have various data types. It is made to store only kubernetes objects. But redis and other key-value stores have data-type flexibility.

• etcd guarantees only high availabilty, but does not give you the fast querying and indexing. All the nosql key-value stores are built with the goal of fast querying and searching.

Eventhough it is obvious that etcd cannot be used as an alternative nosql database, I think the above explanation will prove it cannot be an suitable alternative.