1.場景 這個nosql資料庫適合寫多讀少的情況

2.入門

wget http://mirror.bit.edu.cn/apache/cassandra/3.11.1/apache-cassandra-3.11.1-bin.tar.gz

解壓

tar -xvf apache-cassandra-3.11.1-bin.tar.gz
cd apache-cassandra-3.11.1

修改配置檔案

通用配置
vim conf/cassandra.yaml 
jvm配置
vim conf/jvm.options

啟動

[[email protected] apache-cassandra-3.11
 
.1]# bin/cqlsh localhost
Connected to Test Cluster at localhost:9042.
[cqlsh 5.0.1 | Cassandra 3.11.1 | CQL spec 3.4.4 | Native protocol v4]
Use HELP for help.

建立keyspace

tables由keyspace維護

CQL stores data in tables, whose schema defines the layout of said data in the table, and those tables are grouped in keyspaces.

cqlsh> CREATE KEYSPACE Excelsior
   ...            WITH replication = {'class': 'SimpleStrategy', 'replication_factor' : 3};
cqlsh> use Excelsior;
cqlsh:excelsior> CREATE TABLE t (
             ...     pk int,
             ...     t int,
             ...     v text,
             ...
 
     s text static,
             ...     PRIMARY KEY (pk, t)
             ... );
cqlsh:excelsior> 
cqlsh:excelsior> INSERT INTO t (pk, t, v, s) VALUES (0, 0, 'val0', 'static0');
cqlsh:excelsior> INSERT INTO t (pk, t, v, s) VALUES (0, 1, 'val1', 'static1');
cqlsh:excelsior> 
cqlsh:excelsior> SELECT * FROM t;

 pk | t | s       | v
----+---+---------+------
  0 | 0 | static1 | val0
  0 | 1 | static1 | val1

這個表表示建立了一張名為t的表。屬性pk和t是主鍵，s（有static字尾）是全域性的。
插入和查詢還可以經過JSON

cqlsh:excelsior> select json * from t;

 [json]
------------------------------------------------
 {"pk": 0, "t": 0, "s": "static5", "v": "val0"}
 {"pk": 0, "t": 1, "s": "static5", "v": "val1"}
 {"pk": 0, "t": 2, "s": "static5", "v": "val3"}
 {"pk": 0, "t": 4, "s": "static5", "v": "val4"}
 {"pk": 0, "t": 5, "s": "static5", "v": "val5"}

(5 rows)
cqlsh:excelsior> insert into t json '{"pk": 0, "t": 5, "s": "static6", "v": "val6"}';
cqlsh:excelsior> select json * from t;

 [json]
------------------------------------------------
 {"pk": 0, "t": 0, "s": "static6", "v": "val0"}
 {"pk": 0, "t": 1, "s": "static6", "v": "val1"}
 {"pk": 0, "t": 2, "s": "static6", "v": "val3"}
 {"pk": 0, "t": 4, "s": "static6", "v": "val4"}
 {"pk": 0, "t": 5, "s": "static6", "v": "val6"}

3. 常用運維命令

檢視所有的keyspaces
cqlsh> desc keyspaces

檢視所有的tables
cqlsh> use excelsior;
cqlsh:excelsior> desc tables;
查看錶結構
cqlsh:excelsior> desc table t;

5. 設定外網訪問

修改conf/cassandra.yuml

rpc_address: 0.0.0.0
broadcast_rpc_address: 123.56.13.70

重啟

6. 整合Spring boot cassandra

pom.xml

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-cassandra</artifactId>
        </dependency>

登入cassandra建立keyspace和table

CREATE KEYSPACE mykeyspace WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };

desc keyspaces;

use mykeyspace ;
CREATE TABLE customer (id TimeUUID PRIMARY KEY, firstname text, lastname text);
CREATE INDEX customerfistnameindex ON customer (firstname);
CREATE INDEX customersecondnameindex ON customer (lastname);

app.applications

spring.data.cassandra.keyspace-name=mykeyspace
spring.data.cassandra.contact-points=123.56.13.70
spring.data.cassandra.port=9042

示例程式碼：

@SpringBootApplication
public class DemoCassandraApplication  implements CommandLineRunner {

    @Autowired
    private CustomerRepository repository;

    @Override
    public void run(String... args) throws Exception {
        this.repository.deleteAll();

        // save a couple of customers
        this.repository.save(new Customer(UUIDs.timeBased(), "Alice", "Smith"));
        this.repository.save(new Customer(UUIDs.timeBased(), "Bob", "Smith"));

        // fetch all customers
        System.out.println("Customers found with findAll():");
        System.out.println("-------------------------------");
        for (Customer customer : this.repository.findAll()) {
            System.out.println(customer);
        }
        System.out.println();

        // fetch an individual customer
        System.out.println("Customer found with findByFirstName('Alice'):");
        System.out.println("--------------------------------");
        System.out.println(this.repository.findByFirstName("Alice"));

        System.out.println("Customers found with findByLastName('Smith'):");
        System.out.println("--------------------------------");
        for (Customer customer : this.repository.findByLastName("Smith")) {
            System.out.println(customer);
        }
    }

    public static void main(String[] args) {
            System.out.println("Math.abs(x)" +Math.abs(-2147483648));
            System.out.println(0-(-2147483648));
            System.out.println(Integer.MIN_VALUE);
            ConfigurableApplicationContext ctx = SpringApplication.run(DemoCassandraApplication.class, args);
            ConfigurableEnvironment env =  ctx.getEnvironment();
            String rst = JSON.toJSONString(env, SerializerFeature.PrettyFormat, SerializerFeature.WriteClassName,
                    SerializerFeature.WriteMapNullValue, SerializerFeature.WriteDateUseDateFormat);
            System.out.println(rst);
    }

}

public interface CustomerRepository extends CrudRepository<Customer, String> {

    @Query("Select * from customer where firstname=?0")
    public Customer findByFirstName(String firstName);

    @Query("Select * from customer where lastname=?0")
    public List<Customer> findByLastName(String lastName);
}

@Table
public class Customer {

    @PrimaryKey
    private UUID id;

    private String firstName;

    private String lastName;

    public Customer() {
    }

    public Customer(UUID id, String firstName, String lastName) {
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
    }

    @Override
    public String toString() {
        return String.format("Customer[id=%s, firstName='%s', lastName='%s']", this.id,
                this.firstName, this.lastName);
    }

}