Databases

Databases are external sources that you can connect to and query data from. This includes relational databases, data warehouses, and NoSQL databases, with some sources also supporting external queries for advanced use cases.

note

For the Dremio trial, database sources are not supported.

Relational Databases

These relational databases store data in tables with predefined schemas and use SQL for queries:

• IBM Db2
• Microsoft SQL Server
• MySQL
• Oracle
• PostgreSQL
• SAP HANA

Data Warehouses

These data warehouses are optimized for large-scale analytical queries rather than transactional workloads:

• Amazon Redshift
• Google BigQuery
• Microsoft Azure Synapse Analytics
• Snowflake
• Vertica

NoSQL Databases

These NoSQL databases use flexible schemas and are designed for unstructured or semi-structured data:

• Apache Druid
• MongoDB

External Queries

External queries use native syntax for a source and can be used for SQL statements that are not supported directly in Dremio or are too complex to convert. To run external queries, use the SELECT SQL command with the EXTERNAL_QUERY parameter.

You can run external queries against the following databases: Amazon Redshift, Microsoft SQL Server, MySQL, and PostgreSQL. To run these queries, you need the EXTERNAL QUERY privilege. Keep in mind, however, when you update the metadata for the data source, Dremio clears permissions, formats, and data Reflections for all datasets created from external queries.

When external querying is not enabled, all queries must use standard SQL syntax. Likewise, all user or role read and write access to tables or views within a source are governed by privileges.