Spring BootでApache cassandraを使う – UDTも扱う

Cassandraのインストール
Cassandraのテーブル・データの準備
データを取得するための実装
補足：QueryBuilderを用いたcqlの書き方

Cassandraのインストール

cassandraのインストールは以下を参考に行う

Cassandraのテーブル・データの準備

keyspaceとテーブルの作成は以下。keyspace名はstoreとしている。

bookという名前でテーブルを作成し、primary keyとしてbookのidとversionをセットして、それ以外のカラムにtitle, description, authorsがある。

今回はbookのカラムにauthorsを用意しリストでauthorを持つようにしている。authorはUDT(ユーザ定義型)で定義しカラムにはname, descriptionがある。

cqlsh> CREATE KEYSPACE store WITH replication = {'class': 'SimpleStrategy', 'replication_factor' : 1};
cqlsh> use store;
cqlsh:store>
cqlsh:store> CREATE TYPE author (
         ...   name text,
         ...   description text
         ... );
cqlsh:store> CREATE TABLE book (
         ...     book_id int,
         ...     book_version int,
         ...     title text,
         ...     description text,
         ...     authors list<FROZEN <author>>,
         ...     PRIMARY KEY (book_id, book_version)
         ... );

cqlsh> CREATE KEYSPACE store WITH replication = {'class': 'SimpleStrategy', 'replication_factor' : 1};

cqlsh> use store;

cqlsh:store>

cqlsh:store> CREATE TYPE author (

... name text,

... description text

... );

cqlsh:store> CREATE TABLE book (

... book_id int,

... book_version int,

... title text,

... description text,

... authors list<FROZEN <author>>,

... PRIMARY KEY (book_id, book_version)

... );

データの挿入は以下のように行う。

selectしてみてデータが表示されたら準備はOK。

cqlsh:store> INSERT INTO book (book_id, book_version, title, description, authors) VALUES (1, 1, 'book title 1', 'book description 1',
         ...[{name: 'author name 1-1', description: 'author description 1-1'}, {name: 'author name 1-2', description: 'author description 1-2'}]);
cqlsh:store> INSERT INTO book (book_id, book_version, title, description, authors) VALUES (2, 1, 'book title 2', 'book description 2',
         ...[{name: 'author name 2-1', description: 'author description 2-1'}, {name: 'author name 2-2', description: 'author description 2-2'}]);
cqlsh:store> select * from book;
 book_id | book_version | authors                                                                                                                              | description        | title
---------+--------------+--------------------------------------------------------------------------------------------------------------------------------------+--------------------+--------------
       1 |            1 | [{name: 'author name 1-1', description: 'author description 1-1'}, {name: 'author name 1-2', description: 'author description 1-2'}] | book description 1 | book title 1
       2 |            1 | [{name: 'author name 2-1', description: 'author description 2-1'}, {name: 'author name 2-2', description: 'author description 2-2'}] | book description 2 | book title 2

(2 rows)
cqlsh:store>

cqlsh:store> INSERT INTO book (book_id, book_version, title, description, authors) VALUES (1, 1, 'book title 1', 'book description 1',

...[{name: 'author name 1-1', description: 'author description 1-1'}, {name: 'author name 1-2', description: 'author description 1-2'}]);

cqlsh:store> INSERT INTO book (book_id, book_version, title, description, authors) VALUES (2, 1, 'book title 2', 'book description 2',

...[{name: 'author name 2-1', description: 'author description 2-1'}, {name: 'author name 2-2', description: 'author description 2-2'}]);

cqlsh:store> select * from book;

book_id | book_version | authors | description | title

---------+--------------+--------------------------------------------------------------------------------------------------------------------------------------+--------------------+--------------

1 | 1 | [{name: 'author name 1-1', description: 'author description 1-1'}, {name: 'author name 1-2', description: 'author description 1-2'}] | book description 1 | book title 1

2 | 1 | [{name: 'author name 2-1', description: 'author description 2-1'}, {name: 'author name 2-2', description: 'author description 2-2'}] | book description 2 | book title 2

(2 rows)

cqlsh:store>

データを取得するための実装

src以下のプロジェクト構成は以下。

src
└── main
    ├── java
    │   └── com
    │       └── example
    │           └── springbootcassandra
    │               ├── SpringBootCassandraApplication.java
    │               ├── config
    │               │   └── CassandraConfig.java
    │               ├── controller
    │               │   └── BookController.java
    │               ├── model
    │               │   ├── Author.java
    │               │   ├── Book.java
    │               │   └── BookKey.java
    │               ├── repository
    │               │   └── BookRepository.java
    │               └── service
    │                   └── BookService.java
    └── resources
        ├── application.yml
        ├── static
        └── templates

13 directories, 9 files

src

└── main

├── java

│ └── com

│ └── example

│ └── springbootcassandra

│ ├── SpringBootCassandraApplication.java

│ ├── config

│ │ └── CassandraConfig.java

│ ├── controller

│ │ └── BookController.java

│ ├── model

│ │ ├── Author.java

│ │ ├── Book.java

│ │ └── BookKey.java

│ ├── repository

│ │ └── BookRepository.java

│ └── service

│ └── BookService.java

└── resources

├── application.yml

├── static

└── templates

13 directories, 9 files

build.gradleにcassandraを使う為のライブラリとしてspring-boot-starter-data-cassandraを追加。

dependencies {

    implementation 'org.springframework.boot:spring-boot-starter-web'
    compileOnly 'org.projectlombok:lombok'
    annotationProcessor 'org.springframework.boot:spring-boot-configuration-processor'
    annotationProcessor 'org.projectlombok:lombok'
    // cassandra
    implementation 'org.springframework.boot:spring-boot-starter-data-cassandra'
}

dependencies {

implementation 'org.springframework.boot:spring-boot-starter-web'

compileOnly 'org.projectlombok:lombok'

annotationProcessor 'org.springframework.boot:spring-boot-configuration-processor'

annotationProcessor 'org.projectlombok:lombok'

// cassandra

implementation 'org.springframework.boot:spring-boot-starter-data-cassandra'

}

cassandraのテーブル、カラムと対応するクラスはmodelフォルダ以下の3つで用意する。

Book.java

package com.example.springbootcassandra.model;

import lombok.Getter;
import org.springframework.data.cassandra.core.mapping.Column;
import org.springframework.data.cassandra.core.mapping.PrimaryKey;

import java.util.List;

@Getter
public class Book {
    @PrimaryKey
    private BookKey bookKey;

    @Column
    private String title;

    @Column
    private String description;

    @Column("authors")
    private List<Author> authors;
}

package com.example.springbootcassandra.model;

import lombok.Getter;

import org.springframework.data.cassandra.core.mapping.Column;

import org.springframework.data.cassandra.core.mapping.PrimaryKey;

import java.util.List;

@Getter

public class Book {

@PrimaryKey

private BookKey bookKey;

@Column

private String title;

@Column

private String description;

@Column("authors")

private List<Author> authors;

}

BookKey.java

package com.example.springbootcassandra.model;

import lombok.Getter;
import org.springframework.data.cassandra.core.cql.PrimaryKeyType;
import org.springframework.data.cassandra.core.mapping.PrimaryKeyClass;
import org.springframework.data.cassandra.core.mapping.PrimaryKeyColumn;

@Getter
@PrimaryKeyClass
public class BookKey {
    @PrimaryKeyColumn(name = "book_id", ordinal = 0, type = PrimaryKeyType.PARTITIONED)
    private int bookId;

    @PrimaryKeyColumn(name = "book_version", ordinal = 1, type = PrimaryKeyType.CLUSTERED)
    private int bookVersion;
}

package com.example.springbootcassandra.model;

import lombok.Getter;

import org.springframework.data.cassandra.core.cql.PrimaryKeyType;

import org.springframework.data.cassandra.core.mapping.PrimaryKeyClass;

import org.springframework.data.cassandra.core.mapping.PrimaryKeyColumn;

@Getter

@PrimaryKeyClass

public class BookKey {

@PrimaryKeyColumn(name = "book_id", ordinal = 0, type = PrimaryKeyType.PARTITIONED)

private int bookId;

@PrimaryKeyColumn(name = "book_version", ordinal = 1, type = PrimaryKeyType.CLUSTERED)

private int bookVersion;

}

Author.java

package com.example.springbootcassandra.model;

import lombok.Getter;
import org.springframework.data.cassandra.core.mapping.Column;
import org.springframework.data.cassandra.core.mapping.UserDefinedType;

@UserDefinedType
@Getter
public class Author {
    @Column("name")
    private String name;

    @Column("description")
    private String description;
}

package com.example.springbootcassandra.model;

import lombok.Getter;

import org.springframework.data.cassandra.core.mapping.Column;

import org.springframework.data.cassandra.core.mapping.UserDefinedType;

@UserDefinedType

@Getter

public class Author {

@Column("name")

private String name;

@Column("description")

private String description;

}

Bookクラスがテーブルのbookに対応し、Primary keyをBookKeyクラスとして切り出している。

Primary keyの少なくとも1つはPrimaryKeyColumでPartition keyとして設定しなければならないのでtype = PrimaryKeyType.PARTITIONEDがある。

BookクラスのList<Author> authors;でAuthorクラスをリストで取得できるようにしている。このとき、AuthorクラスにはUserDefinedTypeのアノテーションをつけなければならない。

このクラスらがAPIを通じて取得できることを確認するためにController, Service, Repositoryクラスを以下のように用意する。

BookController.java

package com.example.springbootcassandra.controller;

import com.example.springbootcassandra.model.Book;
import com.example.springbootcassandra.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/book")
public class BookController {

    @Autowired
    BookService bookService;

    @RequestMapping(method = RequestMethod.GET, path = "/{bookId}/{bookVersion}")
    public ResponseEntity<Book> getBook(@PathVariable(value = "bookId") int bookId, @PathVariable(value = "bookVersion") int bookVersion) {
        return new ResponseEntity<>(bookService.getBook(bookId, bookVersion), HttpStatus.OK);
    }
}

package com.example.springbootcassandra.controller;

import com.example.springbootcassandra.model.Book;

import com.example.springbootcassandra.service.BookService;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.http.HttpStatus;

import org.springframework.http.ResponseEntity;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

@RestController

@RequestMapping("/book")

public class BookController {

@Autowired

BookService bookService;

@RequestMapping(method = RequestMethod.GET, path = "/{bookId}/{bookVersion}")

public ResponseEntity<Book> getBook(@PathVariable(value = "bookId") int bookId, @PathVariable(value = "bookVersion") int bookVersion) {

return new ResponseEntity<>(bookService.getBook(bookId, bookVersion), HttpStatus.OK);

}

BookService.java

package com.example.springbootcassandra.service;

import com.example.springbootcassandra.model.Book;
import com.example.springbootcassandra.repository.BookRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class BookService {

    @Autowired
    BookRepository bookRepository;

    public Book getBook(int bookId, int bookVersion) {
        return bookRepository.findById(bookId, bookVersion);
    }
}

package com.example.springbootcassandra.service;

import com.example.springbootcassandra.model.Book;

import com.example.springbootcassandra.repository.BookRepository;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

@Service

public class BookService {

@Autowired

BookRepository bookRepository;

public Book getBook(int bookId, int bookVersion) {

return bookRepository.findById(bookId, bookVersion);

}

BookRepository.java

package com.example.springbootcassandra.repository;

import com.example.springbootcassandra.model.Book;
import com.example.springbootcassandra.model.BookKey;
import org.springframework.data.cassandra.repository.Query;
import org.springframework.data.repository.RepositoryDefinition;

@RepositoryDefinition(domainClass = Book.class, idClass = BookKey.class)
public interface BookRepository {
    @Query("select * from book where book_id=?0 and book_version=?1")
    Book findById(int bookId, int bookVersion);
}

package com.example.springbootcassandra.repository;

import com.example.springbootcassandra.model.Book;

import com.example.springbootcassandra.model.BookKey;

import org.springframework.data.cassandra.repository.Query;

import org.springframework.data.repository.RepositoryDefinition;

@RepositoryDefinition(domainClass = Book.class, idClass = BookKey.class)

public interface BookRepository {

@Query("select * from book where book_id=?0 and book_version=?1")

Book findById(int bookId, int bookVersion);

}

BookRepositoryのRepositoryDefinitionではdomainClassで取得するテーブルクラスを、idClassでPrimary keyの型あるいはクラスを宣言する。

最後にcassandraに繋ぐためのConfigクラスとパラメータを管理するapplication.ymlを以下のように用意する。

CassandraConfig.java

package com.example.springbootcassandra.config;

import com.datastax.driver.core.*;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.data.cassandra.config.AbstractCassandraConfiguration;
import org.springframework.data.cassandra.config.CassandraClusterFactoryBean;
import org.springframework.data.cassandra.config.CassandraSessionFactoryBean;
import org.springframework.data.cassandra.core.CassandraAdminTemplate;
import org.springframework.data.cassandra.repository.config.EnableCassandraRepositories;

@Configuration
@EnableCassandraRepositories(
        basePackages = "com.example.springbootcassandra.repository",
        cassandraTemplateRef = "cassandraTemplate")
public class CassandraConfig extends AbstractCassandraConfiguration {

    @Value("${spring.data.cassandra.username}")
    private String username;

    @Value("${spring.data.cassandra.password}")
    private String password;

    @Value("${spring.data.cassandra.keyspace-name}")
    private String keyspaceName;

    @Value("${spring.data.cassandra.contact-points}")
    private String contactPoints;

    @Value("${spring.data.cassandra.port}")
    private int port;

    @Override
    @Primary
    @Bean(name = "cassandraTemplate")
    public CassandraAdminTemplate cassandraTemplate() {
        Session session = session().getObject();
        return new CassandraAdminTemplate(session, cassandraConverter());
    }

    @Override
    @Bean(name = "Port")
    public int getPort() {
        return port;
    }

    @Override
    @Bean(name = "KeySpace")
    protected String getKeyspaceName() {
        return keyspaceName;
    }

    @Bean(name = "cluster")
    public CassandraClusterFactoryBean cluster() {
        CassandraClusterFactoryBean cluster = new CassandraClusterFactoryBean();
        PlainTextAuthProvider plainTextAuthProvider = new PlainTextAuthProvider(username,password);

        cluster.setContactPoints(contactPoints);
        cluster.setPort(port);
        cluster.setAuthProvider(plainTextAuthProvider);
        cluster.setQueryOptions(new QueryOptions().setConsistencyLevel(ConsistencyLevel.LOCAL_ONE));
        cluster.setSocketOptions(new SocketOptions().setReadTimeoutMillis(5000));
        cluster.setRetryPolicy(getRetryPolicy());
        cluster.setPoolingOptions(new PoolingOptions().setMaxRequestsPerConnection(HostDistance.LOCAL, 10));
        cluster.setJmxReportingEnabled(false);
        return cluster;
    }

    @Override
    @Bean(name = "Session")
    public CassandraSessionFactoryBean session() {

        CassandraSessionFactoryBean session = super.session();
        session.setKeyspaceName(this.getKeyspaceName());

        return session;
    }
}

package com.example.springbootcassandra.config;

import com.datastax.driver.core.*;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import org.springframework.context.annotation.Primary;

import org.springframework.data.cassandra.config.AbstractCassandraConfiguration;

import org.springframework.data.cassandra.config.CassandraClusterFactoryBean;

import org.springframework.data.cassandra.config.CassandraSessionFactoryBean;

import org.springframework.data.cassandra.core.CassandraAdminTemplate;

import org.springframework.data.cassandra.repository.config.EnableCassandraRepositories;

@Configuration

@EnableCassandraRepositories(

basePackages = "com.example.springbootcassandra.repository",

cassandraTemplateRef = "cassandraTemplate")

public class CassandraConfig extends AbstractCassandraConfiguration {

@Value("${spring.data.cassandra.username}")

private String username;

@Value("${spring.data.cassandra.password}")

private String password;

@Value("${spring.data.cassandra.keyspace-name}")

private String keyspaceName;

@Value("${spring.data.cassandra.contact-points}")

private String contactPoints;

@Value("${spring.data.cassandra.port}")

private int port;

@Override

@Primary

@Bean(name = "cassandraTemplate")

public CassandraAdminTemplate cassandraTemplate() {

Session session = session().getObject();

return new CassandraAdminTemplate(session, cassandraConverter());

}

@Override

@Bean(name = "Port")

public int getPort() {

return port;

}

@Override

@Bean(name = "KeySpace")

protected String getKeyspaceName() {

return keyspaceName;

}

@Bean(name = "cluster")

public CassandraClusterFactoryBean cluster() {

CassandraClusterFactoryBean cluster = new CassandraClusterFactoryBean();

PlainTextAuthProvider plainTextAuthProvider = new PlainTextAuthProvider(username,password);

cluster.setContactPoints(contactPoints);

cluster.setPort(port);

cluster.setAuthProvider(plainTextAuthProvider);

cluster.setQueryOptions(new QueryOptions().setConsistencyLevel(ConsistencyLevel.LOCAL_ONE));

cluster.setSocketOptions(new SocketOptions().setReadTimeoutMillis(5000));

cluster.setRetryPolicy(getRetryPolicy());

cluster.setPoolingOptions(new PoolingOptions().setMaxRequestsPerConnection(HostDistance.LOCAL, 10));

cluster.setJmxReportingEnabled(false);

return cluster;

}

@Override

@Bean(name = "Session")

public CassandraSessionFactoryBean session() {

CassandraSessionFactoryBean session = super.session();

session.setKeyspaceName(this.getKeyspaceName());

return session;

}

application.yml

spring:
  data:
    cassandra:
      keyspace-name: store
      username:
      password:
      contact-points: localhost
      port: 9042

spring:

data:

cassandra:

keyspace-name: store

username:

password:

contact-points: localhost

port: 9042

CassandraConfigクラスでは@Valueでapplication.ymlで宣言されたパラメータを取得し、clusterメソッド内でそれを用いてCassandraに繋ぐ為の設定をしている。

いくつか設定の説明を取り上げるとsetReadTimeoutMillis(5000)でcassandraの最大リードタイムを5秒にしている。なのでデータの読み込みに5秒以上かかったらタイムアウトエラーが起こる。

setMaxRequestsPerConnection(HostDistance.LOCAL, 10)ではcassandraへの1つのコネクションに対して同時にリクエストを投げれる数を10までとして設定している。

ここまで行ったらプロジェクトを起動して動作確認をする。

以下のようになっていればOK。

$ curl http://localhost:8080/book/1/1 | jq .
{
  "bookKey": {
    "bookId": 1,
    "bookVersion": 1
  },
  "title": "book title 1",
  "description": "book description 1",
  "authors": [
    {
      "name": "author name 1-1",
      "description": "author description 1-1"
    },
    {
      "name": "author name 1-2",
      "description": "author description 1-2"
    }
  ]
}

$ curl http://localhost:8080/book/1/1 | jq .

{

"bookKey": {

"bookId": 1,

"bookVersion": 1

"title": "book title 1",

"description": "book description 1",

"authors": [

{

"name": "author name 1-1",

"description": "author description 1-1"

{

"name": "author name 1-2",

"description": "author description 1-2"

}

]

}

補足：QueryBuilderを用いたcqlの書き方

BookRepositoryクラスは上記ではinterfaceや@Queryを使ったやり方をしているが以下のように、QueryBuilderを使って書くこともできる。

BookRepository.java

@Component
public class BookRepository {

    @Autowired
    private CassandraAdminTemplate cassandraAdminTemplate;

    public Book findById(int bookId, int bookVersion) {
        Select.Where select = QueryBuilder.select().from("book")
                .where(QueryBuilder.eq("book_id", bookId))
                .and(QueryBuilder.eq("book_version", bookVersion));
        return cassandraAdminTemplate.selectOne(select, Book.class);
    }
}

@Component

public class BookRepository {

@Autowired

private CassandraAdminTemplate cassandraAdminTemplate;

public Book findById(int bookId, int bookVersion) {

Select.Where select = QueryBuilder.select().from("book")

.where(QueryBuilder.eq("book_id", bookId))

.and(QueryBuilder.eq("book_version", bookVersion));

return cassandraAdminTemplate.selectOne(select, Book.class);

}