Glossary

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Glossary / Evaluation and implementation guide

Query Federation

Query federation lets a single SQL query reach data that lives outside the warehouse, in a CRM, ad platform, or another database, at the moment the query runs.

Nothing is copied first; the engine pushes filters to the remote source and pulls back results. It differs from data virtualization as a full architecture and from ETL, which physically copies data ahead of time.

A practical example

Example: an analyst joins warehouse conversion events with campaign names and budgets read live from the ad platform API, producing one attribution table without building a pipeline for that source first.

What to evaluate before investing

  • Test the federated query on a realistic volume and measure runtime, since remote sources respond far slower than local tables.
  • Check which pushdown operations the connector supports, because filters applied remotely versus locally change cost and speed dramatically.
  • Ask about rate limits and authentication on the external source when many analysts run federated queries at once.

Limitations and tradeoffs

Federated queries depend on external API availability and speed, so they suit exploration and light joins, not heavy recurring workloads.

Plan your next step with MeshLine

Connect this decision to your automation, organic marketing and customer lifecycle management. In a MeshLine demo, discuss your existing tools, the scope you need and how to measure the result.