如何在Docker容器中启用Cassandra的物化视图？

官方Cassandra Docker镜像并未提供CASSANDRA_MATERIALIZED_VIEWS_ENABLED这类环境变量，要启用物化视图，需要修改Cassandra核心配置文件或通过启动参数覆盖配置，以下是两种可行方案：

方案一：挂载自定义配置文件 #

1. 先从容器导出默认配置文件到本地：

docker run --rm cassandra:latest cat /etc/cassandra/cassandra.yaml > ./cassandra.yaml

2. 编辑本地的cassandra.yaml，找到materialized_views_enabled项，将值改为true（默认可能为false或被注释）：

materialized_views_enabled: true

3. 修改你的docker-compose.yaml，添加配置文件挂载：

cassandra:
  image: cassandra:latest
  container_name: cassandra
  ports:
    - "9042:9042"
  environment:
    - CASSANDRA_USER=cassandra
    - CASSANDRA_PASSWORD=cassandra
  volumes:
    - ./cassandra.yaml:/etc/cassandra/cassandra.yaml
    - cassandra_data:/var/lib/cassandra
  healthcheck:
    test: [ "CMD", "cqlsh", "-e", "describe keyspaces" ]
    interval: 30s
    timeout: 10s
    retries: 5

4. 重启容器生效：

docker-compose down && docker-compose up -d

方案二：启动时通过命令参数覆盖配置 #

如果不想挂载整个配置文件，可直接在docker-compose中通过启动命令设置参数：

cassandra:
  image: cassandra:latest
  container_name: cassandra
  ports:
    - "9042:9042"
  environment:
    - CASSANDRA_USER=cassandra
    - CASSANDRA_PASSWORD=cassandra
  command: ["cassandra", "-Dmaterialized_views_enabled=true"]
  volumes:
    - cassandra_data:/var/lib/cassandra
  healthcheck:
    test: [ "CMD", "cqlsh", "-e", "describe keyspaces" ]
    interval: 30s
    timeout: 10s
    retries: 5

验证配置是否生效 #

容器启动后，进入cqlsh执行以下命令测试：

CREATE KEYSPACE test_mv WITH replication = {'class': 'SimpleStrategy', 'replication_factor': 1};
USE test_mv;
CREATE TABLE users (id UUID PRIMARY KEY, name TEXT, email TEXT);
CREATE MATERIALIZED VIEW users_by_email AS
    SELECT id, name FROM users
    WHERE email IS NOT NULL AND id IS NOT NULL
    PRIMARY KEY (email, id);

若能成功创建物化视图，则说明配置已生效。

内容的提问来源于stack exchange，提问作者Armani_bologne