9.6. Azure Storage Support for the Hive Connector#

Hive Connector Configuration#

The Hive connector can be configured to query Azure Standard Blob Storage and Azure Data Lake Storage Gen2 (ABFS). Azure Blobs are accessed via the Windows Azure Storage Blob (WASB). This layer is built on top of the HDFS APIs and is what allows for the separation of storage from the cluster.

Starburst Enterprise Presto support both ADLS Gen1 and Gen2. With ADLS Gen2 now generally available, Starburst recommends to use ADLS Gen2. Learn More.

All configuration for the Azure storage driver is stored in the Hadoop core-site.xml configuration file. The path to the file needs to be configure in the the catalog properties file:
hive.config.resources=<path_to_hadoop_core-site.xml>

Configuration for Azure Storage Credentials#

If you do not want to rely on Hadoop’s core-site.xml and want to have Presto configured independently with the storage credentials, you can use the following properties in the catalog configuration.

We suggest to use this kind of configuration when you only have the Primary Storage account linked to the cluster. When there are secondary storage accounts involved, it is recommended to configure Presto using hive.config.resources=<path_to_hadoop_core-site.xml>, provided core-site.xml has the all storage account credentials.

Property Name Description
hive.azure.wasb-storage-account Storage account name of Azure Blob Storage.
hive.azure.wasb-access-key The decrypted access key for the Azure Blob Storage.

If you choose to use ADLS Gen2, you need to add the following properties:

Property Name Description
hive.azure.abfs-storage-account Storage account name of Azure Data Lake Storage Gen2.
hive.azure.abfs-access-key The decrypted access key for the Azure Data Lake Storage Gen2.

While it is advised to migrate to ADLS Gen2 whenever possible, if you still choose to use ADLS Gen1 you need to add the following properties.

Note

Credentials for the filesystem can be configured using ClientCredential type. To authenticate with ADLS Gen1 you must create a new application secret for your ADLS Gen1 account’s App Registration, and save this value because you won’t able to retrieve the key later. Refer to the Azure documentation for details.

Property Name Description
hive.azure.adl-client-id Client (Application) ID from the App Registrations for you storage account.
hive.azure.adl-credential Value of the new client (application) secret created
hive.azure.adl-refresh-url OAuth 2.0 token endpoint URL.

Accessing Azure Storage Data#

URI Scheme to Reference Data

Consistent with other FileSystem implementations within Hadoop, the Azure Standard Blob and Azure Data Lake Storage Gen2 (ABFS) drivers define their own URI scheme so that resources (directories and files) may be distinctly addressed. You can access both primary and secondary storage accounts linked to the cluster with the same URI scheme. Following are example URIs for the different systems.

ABFS URI:

abfs[s]://file_system@account_name.dfs.core.windows.net/<path>/<path>/<file_name>

ADLS Gen1 URI:

adl://<data_lake_storage_gen1_name>.azuredatalakestore.net/<path>/<file_name>

Azure Standard Blob URI:

wasb[s]://container@account_name.blob.core.windows.net/<path>/<path>/<file_name>

Querying Azure Storage

You should be able to query the tables already configured in your Hive metastore used in Presto’s Hive connector. To access Azure Storage data that is not yet mapped in the Hive metastore you need to provide the schema of the data, the file format, and the data location. For example, if you have ORC or Parquet files in an ABFS file_system, you need to execute a query:

-- select schema in which the table is to be defined, must already exist
USE hive.default;

-- create table
CREATE TABLE orders (
     orderkey bigint,
     custkey bigint,
     orderstatus varchar(1),
     totalprice double,
     orderdate date,
     orderpriority varchar(15),
     clerk varchar(15),
     shippriority integer,
     comment varchar(79)
) WITH (
     external_location = 'abfs[s]://file_system@account_name.dfs.core.windows.net/<path>/<path>/<file_name>`',
     format = 'ORC' -- or 'PARQUET'
);

Now you should be able to query the newly mapped table:

SELECT * FROM orders;

Writing Azure Data with Presto#

Prerequisites

Before you attempt to write data to Azure Storage, make sure you have configured everything necessary to read data from the storage.

Create Write Schema

If the Hive metastore contains schema(s) mapped to Azure storage filesystems, you can use them to write data to Azure storage.

If you don’t want to use existing schemas, or there are no appropriate schemas in the Hive metastore, you need to create a new one:

CREATE SCHEMA hive.abfs_export WITH (location = 'abfs[s]://file_system@account_name.dfs.core.windows.net/<path>');

Write Data to Azure storage

Once you have a schema pointing to a location where you want to write the data, you can issue a CREATE TABLE AS statement and select your desired file format. The data will be written to one or more files within the abfs[s]://file_system@account_name.dfs.core.windows.net/<path>/my_table namespace. Example:

CREATE TABLE hive.abfs_export.orders_abfs
WITH (format = 'ORC')
AS SELECT * FROM tpch.sf1.orders;