官术网_书友最值得收藏!

Creating a keyspace

A keyspace is a collection of related tables equivalent to a database in a relational system. To create keyspace, issue the following statement in the CQL shell:

cqlsh> CREATE KEYSPACE "users"
WITH REPLICATION = {
'class': 'SimpleStrategy', 'replication_factor': 1
};

Here, we created a keyspace called users. When we create a keyspace, we have to specify replication options. Cassandra provides several strategies for managing replication of data; SimpleStrategy is the best strategy as long as your Cassandra deployment does not span across multiple data centers. The replication_factor value tells Cassandra how many copies of each piece of data are to be kept in the cluster; since we are only running a single instance of Cassandra, there is no point in keeping more than one copy of the data. In a production deployment, you would certainly want a higher replication factor; three is a good place to start.

A few things at this point are worth noting about CQL's syntax:

  • It's syntactically very similar to SQL; as we further explore CQL, the impression of similarity will not diminish.
  • Double quotes are used for identifiers such as keyspace, table, and column names. As in SQL, quoting identifier names is usually optional, unless the identifier is a keyword or contains a space or another character that will trip up the parser.
  • Single quotes are used for string literals; the key value structure we use for replication is a map literal, which is syntactically similar to an object literal in JSON.
主站蜘蛛池模板: 阜平县| 肥乡县| 贵德县| 博罗县| 若尔盖县| 鞍山市| 和顺县| 临安市| 扶余县| 稷山县| 德格县| 宁德市| 绥化市| 沧源| 南充市| 资溪县| 手游| 邛崃市| 临清市| 容城县| 汝阳县| 南阳市| 台中市| 昌乐县| 沧州市| 南雄市| 沈阳市| 奉化市| 驻马店市| 临潭县| 萝北县| 普格县| 长顺县| 荥阳市| 福泉市| 拜城县| 萨嘎县| 博湖县| 新巴尔虎左旗| 镇宁| 兴安盟|