Cassandra was developed by Facebook to help run the Facebook search box and store / rummage through all the messages from the inbox of users. Was released under Open Source license in July 2008 Cassandra began as an incubation project irish on grand of the Apache Foundation in January 2009 The first version to be released was 0.3 in March 2010, lying currently at version 1.1.6. irish on grand Implemented irish on grand in Java he was strongly irish on grand influenced irish on grand by the Dynamo, Amazon, irish on grand pioneer in the creation of a database of key type / value. Cassandra implements a model for replication of similar data with Dynamo - no single point of failure. But how to store the data is more similar to Google irish on grand Bigtable (oriented columns).
Cassandra has become so popular because of its excellent technical characteristics. It is durable, easily scalable, eventually consistent and fault-tolerant. Can store hundreds of terabytes of data with support for replication across multiple data centers, and is decentralized with no single point of failure, each cluster node is identical. It is highly available and offers irish on grand a free data model schema. In addition to the bank's management to be minimal.
The data model is designed for the Cassandra distributed data on a very large scale, irish on grand ie, thousands irish on grand of data distributed and replicated across multiple machines (nodes) that work together so as to appear as a single irish on grand instance for the end user . Thus Cassandra is probably not the best choice if you only need to run a single node.
The outer structure of the Cassandra cluster is sometimes called the ring and is a container for keyspaces. A cluster can and usually have more than one machine or node that holds a replica for different data tracks. If the first node stops functioning, a replica can answer queries. The peer-to-peer protocol that allows data to be replicated between nodes in a manner transparent to the user, and the replication factor is the number of machines irish on grand in the cluster that will receive copies of the same data.
A keyspace is the tallest container for data in Cassandra. Keyspace The corresponds to a relational database in the world and as well as in the relational world keyspaces have names and attributes that define their behavior. Cassandra allows the creation of several keyspaces per cluster or application, a practice that is not very recommended. For example, if your application is called Twitter, irish on grand you probably have a cluster named Cluster-Twitter and keyspace called Twitter.
Replication factor: The replication factor irish on grand refers to the number of nodes that act as copies (replicas) of each row of data entered. If your replication factor is 3, then three nodes on the ring will have copies of each row inserted, and this replication is transparent to clients. The replication factor essentially lets you decide how much you want to pay in performance to gain more consistency. That is, the level of consistency for reading and writing data is based on the replication factor.
Replica placement strategy: refers to how the replicas will be placed in the ring. There are different strategies for determining which nodes will receive copies of that key (keys) irish on grand which can be:
Family column: the same as a relational database tables is a container for a keyspace is a container for a list of one or more families of column. Each keyspace has at least one and frequently many families column.
A column family is roughly irish on grand analogous to a table in the relational model, and is a container for a collection of lines. Each line contains sorted irish on grand columns. Column represent the family structure of your data.
In the relational world, when you physically create your database from a model by specifying the name of the database (keyspace), table names, and then define the column names that will be on each table.
But the similarities irish on grand stop there, Cassandra schema is considered free because, although the column family are defined, the columns are not. You can freely irish on grand add any column family for any column at any time. A column family has two attributes: a name and a comparator (shown as columns will be arranged when returned irish on grand by a query). The columns are stored in separate files on the disk, it is important to keep related columns defined together in the same column family.
It is a set of columns, ie, for each row of ColumnFamily, we have SuperColumns that have multiple columns. By default column families are configured with the Standard type for super Family column you set your standard for the super kind.
Located within a column or super family Family column, the column is unity over
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