Considerations
This topic describes usage details for cross-database queries in Amazon Redshift.
When you work with the cross-database query feature in Amazon Redshift, consider the following:
Amazon Redshift supports cross-database query on the ra3.4xlarge, ra3.16xlarge, ra3.xlplus, and ra3.large node types.
Amazon Redshift supports joining data from tables or views across one or more databases in the same Amazon Redshift cluster.
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Amazon Redshift Serverless supports the same cross-database capabilities as Amazon Redshift clusters, so you can join data from tables or views across one or more databases in a serverless namespace.
All queries in a transaction on the connected database read data in the same state of the other database as the data was at the beginning of the transaction. This approach helps to provide query transactional consistency across databases. Amazon Redshift supports transactional consistency for cross-database queries.
To get metadata across databases, use SVV_ALL* and SVV_REDSHIFT* metadata views. You can't use the three-part notation or external schemas to query cross-database metadata tables or views under information_schema and pg_catalog.