您的足迹:首页 > Hadoop >Apache Drill学习笔记一:环境搭建和简单试用

Apache Drill学习笔记一:环境搭建和简单试用

简介

Apache Drill是一个低延迟的分布式海量数据(涵盖结构化、半结构化以及嵌套数据)交互式查询引擎,使用ANSI SQL兼容语法,支持本地文件、HDFS、HBase、MongoDB等后端存储,支持Parquet、JSON、CSV、TSV、PSV等数据格式。受Google的Dremel启发,Drill满足上千节点的PB级别数据的交互式商业智能分析场景。

安装

Drill可以安装在单机或者集群环境上,支持Linux、Windows、Mac OS X系统。简单起见,我们在Linux单机环境(CentOS 6.3)搭建以供试用。本文只介绍单机模式使用,集群模式的安装或使用请自行阅读官方文档。

准备安装包:(drill仅支持Java1.7或以上版本)

在$WORK(/path/to/work)目录中安装,将jdk和drill分别解压到java和drill目录中,并打软连以便升级:

.
├── drill
│   ├── apache-drill -> apache-drill-0.8.0
│   └── apache-drill-0.8.0
├── init.sh
└── java
    ├── jdk -> jdk1.7.0_75
    └── jdk1.7.0_75

并添加一init.sh脚本初始化java相关环境变量:

export WORK="/path/to/work"
export JAVA="$WORK/java/jdk/bin/java"
export JAVA_HOME="$WORK/java/jdk"

启动

在单机环境运行只需要启动bin/sqlline便可:

$ cd $WORK
$ . ./init.sh
$ ./drill/apache-drill/bin/sqlline -u jdbc:drill:zk=local
Drill log directory /var/log/drill does not exist or is not writable, defaulting to ...
Apr 06, 2015 12:47:30 AM org.glassfish.jersey.server.ApplicationHandler initialize
INFO: Initiating Jersey application, version Jersey: 2.8 2014-04-29 01:25:26...
sqlline version 1.1.6
0: jdbc:drill:zk=local> 

-u jdbc:drill:zk=local表示使用本机的Drill,无需启动ZooKeeper,如果是集群环境则需要配置和启动ZooKeeper并填写地址。启动后便可以在0: jdbc:drill:zk=local>后敲入命令使用了。

试用

Drill的sample-data目录有Parquet格式的演示数据可供查询:

注意:dfs.后面跟的是`号,在键盘的左上角,esc下面的键。

0: jdbc:drill:zk=local> select * from dfs.`/path/to/work/drill/apache-drill/sample-data/nation.parquet` limit 5;
+-------------+------------+-------------+------------+
| N_NATIONKEY |   N_NAME   | N_REGIONKEY | N_COMMENT  |
+-------------+------------+-------------+------------+
| 0           | ALGERIA    | 0           |  haggle. carefully f |
| 1           | ARGENTINA  | 1           | al foxes promise sly |
| 2           | BRAZIL     | 1           | y alongside of the p |
| 3           | CANADA     | 1           | eas hang ironic, sil |
| 4           | EGYPT      | 4           | y above the carefull |
+-------------+------------+-------------+------------+
5 rows selected (0.741 seconds)

这里用的库名格式为dfs.`本地文件(Parquet、JSON、CSV等文件)绝对路径`。可以看出只要熟悉SQL语法几乎没有学习成本。但Parquet格式文件需要专用工具查看、编辑,不是很方便,后续再专门介绍,下文先使用更通用的CSV和JSON文件进行演示。

在$WORK/data中创建如下test.csv文件:

1101,SteveEurich,Steve,Eurich,16,StoreT
1102,MaryPierson,Mary,Pierson,16,StoreT
1103,LeoJones,Leo,Jones,16,StoreTem
1104,NancyBeatty,Nancy,Beatty,16,StoreT
1105,ClaraMcNight,Clara,McNight,16,Store

然后查询:

0: jdbc:drill:zk=local> select * from dfs.`/path/to/work/drill/data/test.csv`;
+------------+
|  columns   |
+------------+
| ["1101","SteveEurich","Steve","Eurich","16","StoreT"] |
| ["1102","MaryPierson","Mary","Pierson","16","StoreT"] |
| ["1103","LeoJones","Leo","Jones","16","StoreTem"] |
| ["1104","NancyBeatty","Nancy","Beatty","16","StoreT"] |
| ["1105","ClaraMcNight","Clara","McNight","16","Store"] |
+------------+
5 rows selected (0.082 seconds)

可以看到结果和之前的稍有不同,因为CSV文件没有地方存放列列名,所以统一用columns代替,如果需要具体制定列则需要用columns[n],如:

0: jdbc:drill:zk=local> select columns[0], columns[3] from dfs.`/path/to/work/drill/data/test.csv`;
+------------+------------+
|   EXPR$0   |   EXPR$1   |
+------------+------------+
| 1101       | Eurich     |
| 1102       | Pierson    |
| 1103       | Jones      |
| 1104       | Beatty     |
| 1105       | McNight    |
+------------+------------+

CSV文件格式比较简单,发挥不出Drill的强大优势,下边更复杂的功能使用和Parquet更接近的JSON文件进行演示。

在$WORK/data中创建如下test.json文件:

{
  "ka1": 1,
  "kb1": 1.1,
  "kc1": "vc11",
  "kd1": [
    {
      "ka2": 10,
      "kb2": 10.1,
      "kc2": "vc1010"
    }
  ]
}
{
  "ka1": 2,
  "kb1": 2.2,
  "kc1": "vc22",
  "kd1": [
    {
      "ka2": 20,
      "kb2": 20.2,
      "kc2": "vc2020"
    }
  ]
}
{
  "ka1": 3,
  "kb1": 3.3,
  "kc1": "vc33",
  "kd1": [
    {
      "ka2": 30,
      "kb2": 30.3,
      "kc2": "vc3030"
    }
  ]
}

可以看到这个JSON文件内容是有多层嵌套的,结构比之前那个CSV文件要复杂不少,而查询嵌套数据正是Drill的优势所在。

0: jdbc:drill:zk=local> select * from dfs.`/path/to/work/drill/data/test.json`;
+------------+------------+------------+------------+
|    ka1     |    kb1     |    kc1     |    kd1     |
+------------+------------+------------+------------+
| 1          | 1.1        | vc11       | [{"ka2":10,"kb2":10.1,"kc2":"vc1010"}] |
| 2          | 2.2        | vc22       | [{"ka2":20,"kb2":20.2,"kc2":"vc2020"}] |
| 3          | 3.3        | vc33       | [{"ka2":30,"kb2":30.3,"kc2":"vc3030"}] |
+------------+------------+------------+------------+
3 rows selected (0.098 seconds)

select *只查出第一层的数据,更深层的数据只以原本的JSON数据呈现出来,我们显然不应该只关心第一层的数据,具体怎么查完全随心所欲:

0: jdbc:drill:zk=local> select sum(ka1), avg(kd1[0].kb2) from dfs.`/path/to/work/drill/data/test.json`;
+------------+------------+
|   EXPR$0   |   EXPR$1   |
+------------+------------+
| 6          | 20.2       |
+------------+------------+
1 row selected (0.136 seconds)

可以通过kd1[0]来访问嵌套到第二层的这个表。

0: jdbc:drill:zk=local> select kc1, kd1[0].kc2 from dfs.`/path/to/work/drill/data/test.json` where kd1[0].kb2 = 10.1 and ka1 = 1;
+------------+------------+
|    kc1     |   EXPR$1   |
+------------+------------+
| vc11       | vc1010     |
+------------+------------+
1 row selected (0.181 seconds)

创建view:

0: jdbc:drill:zk=local> create view dfs.tmp.tmpview as select kd1[0].kb2 from dfs.`/path/to/work/drill/data/test.json`;
+------------+------------+
|     ok     |  summary   |
+------------+------------+
| true       | View 'tmpview' created successfully in 'dfs.tmp' schema |
+------------+------------+
1 row selected (0.055 seconds)

0: jdbc:drill:zk=local> select * from dfs.tmp.tmpview;
+------------+
|   EXPR$0   |
+------------+
| 10.1       |
| 20.2       |
| 30.3       |
+------------+
3 rows selected (0.193 seconds)

可以把嵌套的第二层表打平(整合kd1[0]..kd1[n]):

0: jdbc:drill:zk=local> select kddb.kdtable.kc2 from (select flatten(kd1) kdtable from dfs.`/path/to/work/drill/data/test.json`) kddb;
+------------+
|   EXPR$0   |
+------------+
| vc1010     |
| vc2020     |
| vc3030     |
+------------+
3 rows selected (0.083 seconds)

使用细节上和mysql还是有所不同的,另外涉及到多层表的复杂逻辑,要想用得得心应手还需要仔细阅读官方文档并多多练习。这次先走马观花了,之后会深入了解语法层面的特性。

参考

本博客所有文章如无特别注明均为原创。作者:数据为王复制或转载请以超链接形式注明转自 数据为王
原文地址《Apache Drill学习笔记一:环境搭建和简单试用

相关推荐


  • blogger

发表评论

路人甲 表情
看不清楚?点图切换 Ctrl+Enter快速提交

网友评论(0)