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Introductie van Micorosoft SQL Server 2016

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92 C H A P T E R 5 | Broader data access Example 5-30: Creating a database-scoped credential for Kerberos-enabled Hadoop -- Create a master key if one does not already exist CREATE MASTER KEY ENCRYPTION BY PASSWORD = ''; -- Create a database-scoped credential CREATE DATABASE SCOPED CREDENTIAL HadoopCredential WITH IDENTITY = '', SECRET = ''; External data source An external data source tells PolyBase where to find your data. If you are using blob storage, you specify the name of the blob container and the storage account in the LOCATION argument of the CREATE EXTERNAL DATA SOURCE statement, as shown in Example 5-31. The CREDENTIAL argument uses the database-scoped credential that you created for accessing blob storage. Example 5-31: Creating an external data source for blob storage CREATE EXTERNAL DATA SOURCE AzureBlobStorage with ( TYPE = HADOOP, LOCATION ='wasbs://@.blob.core.windows.net/', CREDENTIAL = AzureBlobStorageCredential ); To create an external data source for Hadoop storage, you specify the Uniform Resource Indicator (URI) for Hadoop in the LOCATION argument of the CREATE EXTERNAL DATA SOURCE statement, as shown in Example 5-32. For Hadoop storage, you can optionally include the RESOURCE_MANAGER_LOCATION argument and provide the address and port for the Hadoop Name Node. If you enabled pushdown computations for PolyBase, SQL Server's query optimizer can send data to the Name Node for preprocessing to reduce the volume of data transferred between SQL Server and Hadoop. If you omit this argument, pushdown computations are disabled. Example 5-32: Creating an external data source for Hadoop storage CREATE EXTERNAL DATA SOURCE HadoopStorage WITH ( TYPE = HADOOP, LOCATION ='hdfs://10.10.10.10:8020', RESOURCE_MANAGER_LOCATION = '10.10.10.10:8032', CREDENTIAL = HadoopCredential ); External file format You must create an external file format to describe the general structure of your data by using the CREATE EXTERNAL FILE FORMAT statement applicable to your file type, as shown in Example 5-33. You define the structure of your data by using the following arguments: FORMAT_TYPE You can use one of the following options: PARQUET, ORC, RCFILE, or DELIMITEDTEXT. If you use RCFILE, you must also specify one of the following Hive Serializer and Deserializer (SerDe) methods: org.apache.hadoop.hive.serde2.columnar.LazyBinaryColumnarSerDe or org.apache.hadoop.hive.serde2.columnar.ColumnarSerDe.

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