DW(六):polybase访问Azure Blob Storage

连接hadoop配置语法
配置hadoop连接
Pushdown配置
Create external tables for Azure blob storage

连接hadoop配置语法：

global configuration settings for PolyBase Hadoop and Azure blob storage connectivity, Syntax:

sp_configure: List all of the configuration options
配置与hadoop连接语法：

sp_configure [ @configname = ] 'hadoop connectivity',  
             [ @configvalue = ] { 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 }  
[;]  
  
RECONFIGURE  
[;]

Option 0: Disable Hadoop connectivity
Option 1: Hortonworks HDP 1.3 on Windows Server
Option 1: Azure blob storage (WASB[S])
Option 2: Hortonworks HDP 1.3 on Linux
Option 3: Cloudera CDH 4.3 on Linux
Option 4: Hortonworks HDP 2.0 on Windows Server
Option 4: Azure blob storage (WASB[S])
Option 5: Hortonworks HDP 2.0 on Linux
Option 6: Cloudera 5.1, 5.2, 5.3, 5.4, and 5.5 on Linux
Option 7: Hortonworks 2.1, 2.2, and 2.3 on Linux
Option 7: Hortonworks 2.1, 2.2, and 2.3 on Windows Server
Option 7: Azure blob storage (WASB[S])

示例代码：

显示所有可用的配置列表： EXEC sp_configure;
显示某个配置项的配置信息: EXEC sp_configure @configname='hadoop connectivity';
设置配置项示例语法如下：

sp_configure @configname = 'hadoop connectivity', @configvalue = 7;  
GO  
  
RECONFIGURE  
GO

配置hadoop连接

在本节示例中，连接HDInsight3.2集，对应关系如下：
配置polybase连接配置项信息信息如下：

sp_configure @configname = 'hadoop connectivity', @configvalue = 7;  
GO  
  
RECONFIGURE  
GO

命令行： services.msc，重启下面的服务
1. SQL Server PolyBase Data Movement Service
2. SQL Server PolyBase Engine

Pushdown配置:

To improve query performance, enable pushdown computation to a Hadoop cluster

Find the file yarn-site.xml in the installation path of SQL Server. Typically, the path is: C:Program FilesMicrosoft SQL ServerMSSQL13.MSSQLSERVERMSSQLBinnPolybaseHadoopconf
On the Hadoop machine, find the analogous(类似) file in the Hadoop configuration directory. In the file, find and copy the value of the configuration key yarn.application.classpath
On the SQL Server machine, in the yarn-site.xml file, find the yarn.application.classpath property. Paste the value from the Hadoop machine into the value element.

$HADOOP_CONF_DIR,/usr/hdp/current/hadoop-client/*,/usr/hdp/current/hadoop-client/lib/*,/usr/hdp/current/hadoop-hdfs-client/*,/usr/hdp/current/hadoop-hdfs-client/lib/*,/usr/hdp/current/hadoop-yarn-client/*,/usr/hdp/current/hadoop-yarn-client/lib/*

Create external tables for Azure blob storage

The Elastic（弹性） Database query feature relies on(依靠） the these four DDL statements. Typically, these DDL statements are used once or rarely when the schema of your application changes

1. [CREATE MASTER KEY] (https://msdn.microsoft.com/library/ms174382.aspx)
2. [CREATE CREDENTIAL] (https://msdn.microsoft.com/library/ms189522.aspx)
3. [CREATE DATABASE SCOPED CREDENTIAL] (https://msdn.microsoft.com/library/mt270260.aspx)
4. [CREATE/DROP EXTERNAL DATA SOURCE] (https://msdn.microsoft.com/library/dn935022.aspx)
5. [CREATE/DROP EXTERNAL TABLE] (https://msdn.microsoft.com/library/dn935021.aspx)

You can use the following syntax to drop the master key and credentials

1. DROP CREDENTIAL <credential_name> ON DATABASE;
2. DROP DATABASE SCOPED CREDENTIAL <credential_name>;
3. DROP MASTER KEY;

模拟简单文本数据，如下：
将文本文件上传到 Azure blob storage, 如下图：
远程连接ploybase1, 打开ssms(注：此版本需单独安装），执行脚本如下：

CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'Password01!'; 

CREATE DATABASE SCOPED CREDENTIAL JNAzureCredit   
WITH IDENTITY = 'zhushy', Secret =  XXXX';  /*存储访问Key*/ 


CREATE EXTERNAL DATA SOURCE JNAzureStorage with (  
        TYPE = HADOOP,   
        LOCATION ='wasb://<blob_container_name>@<azure_storage_account_name>.blob.core.chinacloudapi.cn',  
        CREDENTIAL = JNAzureCredit  
);


CREATE EXTERNAL FILE FORMAT TextFileFormat WITH (  
        FORMAT_TYPE = DELIMITEDTEXT,   
        FORMAT_OPTIONS (FIELD_TERMINATOR =' ', USE_TYPE_DEFAULT = TRUE))

CREATE EXTERNAL TABLE [dbo].[hospital] (  
        [ID] varchar(128) NULL,
        [name] varchar(128) null
)  
WITH (LOCATION='/zhu/data1.txt',   
        DATA_SOURCE = JNAzureStorage,  
        FILE_FORMAT = TextFileFormat  
);

验证数据，输入如下SQL： select * from [dbo].[hospital] ，如下图，则OK