How Discord Stores Billions of Messages Using Cassandra
<i>&gt; While Cassandra has schemas not unlike a relational database, they are cheap to alter and do not impose any temporary performance impact</i><p>in most relational databases, the schema is cheap to alter and does not impose a temporary performance impact.<p>In-fact, all of their requirements (aside of linear scalability) could also be met with a relational database. Doing so would gain you much more flexible access to querying for various reports and it would reduce the engineering effort required for retrieval of data as they add more features (relational databases are really good at being queried for arbitrary constraints).<p>I think people tend to dismiss relational databases a bit too quickly these days.