🧩PolyBase

NEW

A SQL technology enabling T‐SQL queries over external data sources via external tables and pushdown.

DESCRIPTION

PolyBase lets SQL Server and Azure Synapse query external data using T‑SQL, creating external tables that reference data in Hadoop, blob storage, or other RDBMSs. It can push computation to external engines for performance and supports transparent data access without moving or copying all data. PolyBase simplifies data virtualization and federation within analytical platforms. Configuration requires data source definitions, credentials, and format settings.

ALTERNATIVE DEFINITIONS

Microsoft Learn

Use PolyBase to query data stored in external data sources by using T-SQL.

Directly describes external querying with T-SQL.

Source

Microsoft Learn

PolyBase enables you to access data stored in Hadoop or in Azure Blob Storage or Azure Data Lake Storage via T-SQL.

Enumerates supported storage systems and T‑SQL access.

Source

RELATED TERMS

External Tables SQL Server Azure Synapse Analytics Data Virtualization Hadoop Azure Data Lake Storage Pushdown T-SQL Data Lakehouse Query Federation

COMPETING TERMS

Linked Servers Presto

KNOWLEDGE AREAS

Data Integration & Interoperability Data Services Data Architecture Data Engineering Cloud

TARGET AUDIENCE

Data Engineer Data Architect BI Specialist Analytics Engineer Cloud Architect

EXTERNAL SOURCES

• Wikipedia - Azure Synapse Analytics
• Microsoft - Comprehensive PolyBase guide
• Microsoft - PolyBase in Synapse overview
• SQL Server Central - Community tutorial on setup

TOP QUESTIONS

What is PolyBase?

A SQL technology that lets you query external data sources using T‑SQL via external tables and pushdown.

Category: Definition

Which systems does PolyBase support?

Hadoop, Azure Blob Storage, Azure Data Lake Storage, and certain external RDBMSs through connectors.

Category: Overview

Why use PolyBase?

It enables data virtualization and federation, reducing data movement while maintaining SQL access.

Category: Relevancy

How does pushdown work in PolyBase?

Where supported, computations are delegated to external engines, improving performance on large datasets.

Category: Concepts

What are common setup mistakes with PolyBase?

Incorrect data source credentials, format misconfigurations, and insufficient permissions cause query failures.

Category: Mistakes

Is PolyBase the same as linked servers?

No. PolyBase focuses on external big data and file storage with pushdown; linked servers are classic RDBMS federation.

Category: Comparison

How to secure PolyBase data access?

Use managed identities, secure credentials, storage ACLs, and restrict external table exposure.

Category: Best practices

What performance considerations exist?

Optimize file formats, partitioning, and leverage pushdown; avoid small-file problems and tune resource classes.

Category: Requirements

Where to learn PolyBase configuration?

Microsoft Learn guides and community tutorials on SQL Server Central offer step-by-step setup.

Category: Learning