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title Introducing Data Virtualization with PolyBase
description PolyBase enables your SQL Server instance to process Transact-SQL queries that read data from external data sources, such as Azure Blob Storage.
author MikeRayMSFT
ms.author mikeray
ms.reviewer hudequei, randolphwest
ms.date 04/29/2025
ms.service sql
ms.subservice polybase
ms.topic overview
ms.custom
intro-overview
build-2025
f1_keywords
PolyBase
PolyBase, guide
helpviewer_keywords
PolyBase
PolyBase, overview
Hadoop import
Hadoop export
Hadoop export, PolyBase overview
Hadoop import, PolyBase overview
monikerRange >=sql-server-2016 || >=sql-server-linux-ver15 || >=aps-pdw-2016 || =azure-sqldw-latest

Data virtualization with PolyBase in SQL Server

[!INCLUDE appliesto-ss-xxxx-asdw-pdw-md]

PolyBase is a data virtualization feature for [!INCLUDE ssNoVersion].

What is PolyBase?

PolyBase enables your [!INCLUDE ssNoVersion] instance to query data with T-SQL directly from [!INCLUDE ssNoVersion], Oracle, Teradata, MongoDB, Hadoop clusters, Cosmos DB, and S3-compatible object storage without separately installing client connection software. You can also use the generic ODBC connector to connect to additional providers using third-party ODBC drivers. PolyBase allows T-SQL queries to join the data from external sources to relational tables in an instance of [!INCLUDE ssNoVersion].

A key use case for data virtualization with the PolyBase feature is to allow the data to stay in its original location and format. You can virtualize the external data through the [!INCLUDE ssNoVersion] instance, so that it can be queried in place like any other table in [!INCLUDE ssNoVersion]. This process minimizes the need for ETL processes for data movement. This data virtualization scenario is possible with the use of PolyBase connectors.

Supported SQL products and services

PolyBase provides these same functionalities for the following SQL products from Microsoft:

Note

Data virtualization is also available for Azure SQL Managed Instance, scoped to querying external data stored in files in Azure Data Lake Storage (ADLS) Gen2 and Azure Blob Storage. For more information, see Data virtualization with Azure SQL Managed Instance.

SQL Server 2025 PolyBase enhancements

New to [!INCLUDE sssql25-md] Details
Native support for CSV, Parquet, & Delta 1 You don't have to install PolyBase Query Service for External Data to use OPENROWSET, CREATE EXTERNAL TABLE, or CREATE EXTERNAL TABLE AS SELECT with the following types of external data: Parquet, Delta, Azure Blob Storage (ABS), Azure Data Lake Storage (ADLS), or S3-Compatible Object storage.
Use generic ODBC data sources on Linux For more information, see Configure PolyBase to access external data with ODBC generic types.

1 On [!INCLUDE sssql25-md], PolyBase Query Service for External Data is still required to connect with other databases. For example: SQL Server, Oracle, DB2, Teradata, MongoDB, or ODBC.

SQL Server 2022 PolyBase enhancements

New to [!INCLUDE sssql22-md] Details
S3-compatible object storage [!INCLUDE sssql22-md] adds new connector, S3-compatible object storage, using the S3 REST API. You can use both OPENROWSET and CREATE EXTERNAL TABLE to query data files in S3-compatible object storage.
Some connectors separate from PolyBase services The S3-compatible object storage connector, ADSL Gen2, and Azure Blob Storage, are no longer dependent of PolyBase services. PolyBase services must still run to support connectivity with Oracle, Teradata, MongoDB, and Generic ODBC. The PolyBase feature must still be installed on your SQL Server instance.
Parquet file format PolyBase is now capable of querying data from Parquet files stored on S3-compatible object storage. For more information, see to Virtualize parquet file in a S3-compatible object storage with PolyBase.
Delta table format PolyBase is now capable of querying (read-only) data from Delta Table format stored on S3-compatible object storage, Azure Storage Account V2, and Azure Data Lake Storage Gen2. For more information, see to Virtualize delta table with PolyBase
Create External Table as Select (CETAS) PolyBase can now use CETAS to create an external table and then export, in parallel, the result of a [!INCLUDE tsql] SELECT statement to Azure Data Lake Storage Gen2, Azure Storage Account V2, and S3-compatible object storage. For more information, see CREATE EXTERNAL TABLE AS SELECT (CETAS).

For more new features of [!INCLUDE sssql22-md], see What's new in SQL Server 2022?

Tip

For a tutorial of PolyBase features and capabilities in [!INCLUDE sssql22-md], see Get started with PolyBase in SQL Server 2022.

PolyBase connectors

The PolyBase feature provides connectivity to the following external data sources:

External data sources [!INCLUDE ssNoVersion] 2016-2019 with PolyBase [!INCLUDE sssql22-md] with PolyBase APS PDW [!INCLUDE ssazuresynapse-md]
Oracle, MongoDB, Teradata Read Read No No
Generic ODBC Read (Windows Only) Read (Windows Only) No No
Azure Storage Read/Write Read/Write Read/Write Read/Write
Hadoop Read/Write No Read/Write No
SQL Server Read Read No No
S3-compatible object storage No Read/Write No No
  • [!INCLUDE sssql22-md] doesn't support Hadoop.
  • [!INCLUDE sssql16-md] introduced PolyBase with support for connections to Hadoop and Azure Blob Storage.
  • [!INCLUDE sssql19-md] introduced more connectors, including [!INCLUDE ssNoVersion], Oracle, Teradata, and MongoDB.
  • [!INCLUDE sssql22-md] introduced the S3-compatible storage connector.
  • [!INCLUDE sssql19-md] Cumulative update 19 introduced support for Oracle TNS.
  • [!INCLUDE sssql22-md] Cumulative update 2 introduced support for Oracle TNS.

Examples of external connectors include:

* PolyBase supports two Hadoop providers, Hortonworks Data Platform (HDP) and Cloudera Distributed Hadoop (CDH), through SQL Server 2019. [!INCLUDE polybase-java-connector-banner-retirement]

To use PolyBase in an instance of [!INCLUDE ssNoVersion]:

  1. Install PolyBase on Windows or Install PolyBase on Linux.
  2. Starting with [!INCLUDE sssql19-md], enable PolyBase in sp_configure, if necessary.
  3. Create an external data source.
  4. Create an external table.

Azure integration

With the underlying help of PolyBase, T-SQL queries can also import and export data from Azure Blob Storage. Further, PolyBase enables [!INCLUDE ssazuresynapse-md] to import and export data from Azure Data Lake Store, and from Azure Blob Storage.

Why use PolyBase?

PolyBase lets you join data from a [!INCLUDE ssNoVersion] instance with external data. Before PolyBase allowed joining data to external data sources, you could either:

  • Transfer half your data so that all the data was in one location.
  • Query both sources of data, then write custom query logic to join and integrate the data at the client level.

PolyBase lets you use Transact-SQL to join the data.

PolyBase doesn't require you to install extra software to your Hadoop environment. You query external data by using the same T-SQL syntax used to query a database table. The support actions implemented by PolyBase all happen transparently. The query author doesn't need any knowledge about the external source.

PolyBase uses

PolyBase enables the following scenarios in [!INCLUDE ssNoVersion]:

  • Query data stored in Azure Blob Storage. Azure Blob Storage is a convenient place to store data for use by Azure services. PolyBase makes it easy to access the data by using T-SQL.

  • Query data stored in Hadoop from a SQL Server instance or PDW. Users are storing data in cost-effective distributed and scalable systems, such as Hadoop. PolyBase makes it easy to query the data by using T-SQL.

  • Import data from Hadoop, Azure Blob Storage, or Azure Data Lake Store. Use the speed of Microsoft SQL's columnstore technology and analysis capabilities by importing data from Hadoop, Azure Blob Storage, or Azure Data Lake Store into relational tables. There's no need for a separate ETL or import tool.

  • Export data to Hadoop, Azure Blob Storage, or Azure Data Lake Store. Archive data to Hadoop, Azure Blob Storage, or Azure Data Lake Store to achieve cost-effective storage and keep it online for easy access.

  • Integrate with BI tools. Use PolyBase with Microsoft's business intelligence and analysis stack, or use any third-party tools that are compatible with [!INCLUDE ssNoVersion].

Performance

There's no hard limit to the number of files or the amount of data that can be queried. Query performance depends on the amount of data, data format, the way data is organized, and complexity of queries and joins.

For more information on performance guidance and recommendations for PolyBase, see Performance considerations in PolyBase for SQL Server.

Upgrade to SQL Server 2022

Starting in [!INCLUDE sssql22-md] Hortonworks Data Platform (HDP) and Cloudera Distributed Hadoop (CDH) are no longer supported. Due to these changes, it's required to manually drop PolyBase external data sources created on previous versions of SQL Server that use TYPE = HADOOP or Azure Storage before migrating to [!INCLUDE sssql22-md]. Dropping external data sources also requires dropping the associated database objects, such as database scoped credentials and external tables.

Azure Storage connectors must be changed based on the following reference table:

External data source From To
`Azure Blob Storage wasb[s] abs
ADLS Gen 2 abfs[s] adls

Get started

Before using PolyBase, you must install PolyBase on Windows or install PolyBase on Linux, and enable PolyBase in sp_configure if necessary.

For a tutorial of PolyBase features and capabilities, see Get started with PolyBase in SQL Server 2022.

For more tutorials on various external data sources, review:

Data virtualization on other platforms

Data virtualization features are also available on other platforms:

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