where is the index physically located in MySQL database?

What are the advantages of NoSQL with Cassandra over MySQL?

• I work on large database (hundreds of GB) and Mysql now gives me more or less satisfaction. I hesitate to cassandra on launch.  What I want to know everything before, so this kind of DBMS NoSQL is supposed to be faster than MySQL?  Several points: The change in the number of column on a row In Mysql, they must all be defined in advance. The columns set in the structure of the table. NoSQL in, they can be varied. There is real difference performance on a fixed structure ? and why ? Do not make the relationship is beneficial for performance. Ok but I am not obliged to make a relational table Mysql. I use aggregated tables, ie tables that contain only data derived from other tables, I to prevent the joints which are too expensive. Again what level performance differences if I use this model in Mysql? To take one example, the author of http://www.rackspacecloud.com/blog/2010/05/12/cassandra-by-example/ insert X number of times the follower in the message USERLINE pusher. I could do that in MySQL. Scalability, scalability, scalability ... I like it, do cassandra allow me to store my data on different servers (without SAN) ? I am not talking here of replication, I speak of a single NoSQL server across multiple physical server. Live at the calculations. MySQL provides functions like me as  SUM, AVG ... that are very useful to avoid me to re-aggregating my data  in other tables. I have not seen equivalent cassandra ? What about the indexes. On Mysql I index several fields in one.  For example my tables have a primary key on multiple columns and I  select are in functionaly. cassandra on how to write it? The  concatenated for a single identifier for each row? I think I have not  completely grasped the management of indexes. Are recalculated for the  integration or upstream? The asynchronous requests. A false argument that it seems to me, Mysql can be done with INSERT / UPDATE LOW_PRIORITY.

• Answer:

  See this related topic on some of the NoSQL solutions - . Data size and performance shouldn't be the only considerations and any architecture should have a mix of appropriate solutions. The main difference from architectural perspective is that NoSQL solutions are schema-less, but they are all not created equal. The downside of this is query-ability, so if your application needs extensive querying on the same set of data, you will be disappointed with the choice. So, don't set your eyes on Cassandra alone, but evaluate the available NoSQL solutions and see which one of them fits/complements your situation.