Multi-cloud data engineering means using services from more than one cloud provider in the same data platform — AWS S3 as the data lake, Snowflake (running on AWS or Azure) as the warehouse, and Azure Active Directory for identity management. Hybrid data engineering extends this to include on-premises systems alongside cloud services — an Oracle database on-premises feeding an Azure Synapse warehouse in the cloud. Neither strategy is inherently better than single-cloud; they reflect organisational constraints (existing contracts, data residency requirements, vendor risk diversification) rather than purely technical choices.
The data gravity problem is the primary technical challenge in multi-cloud architectures: data accumulates where it was first created, and moving it across clouds incurs significant egress charges and latency. AWS charges $0.09/GB for data transfer out; GCP charges $0.08/GB. Moving 10TB from AWS S3 to GCP BigQuery costs approximately $900 in egress fees alone. Analytical workloads should run in the same cloud as the data they process, even if the organisation has a strategic preference for a different cloud for other workloads.