Querausführung

Querausführung is a concept used in computing to describe the coordinated execution of queries or commands across multiple data sources or modules. The term combines the German elements quer, meaning across or cross, and ausführung, meaning execution. It is often employed in discussions of federated databases, distributed analytics, and data virtualization, where a single logical query must be realized by actions on several heterogeneous systems.

In practice, querausführung involves a dedicated component or layer that plans, orchestrates, and monitors the cross-source query process. A typical architecture includes a query planner, a cross-source orchestrator, adapters or connectors to individual data sources, and an execution engine that deploys subqueries to each source and collects results for fusion and final presentation. The workflow usually starts with a user submission of a high-level query, followed by decomposition into source-specific subqueries, parallel execution, result merging, and aggregation to produce a unified answer. This approach aims to minimize data movement, reduce latency, and enable analytics across distributed datasets while maintaining a coherent result set.

Advantages of querausführung include improved scalability, faster access to distributed data, and the ability to leverage source-native processing. Key challenges involve handling data heterogeneity, varying data models and schemas, network reliability, security and access control, and ensuring consistency and correctness in the presence of partial failures.

The term is most often used in contexts where data resides in multiple sources or domains, and a centralized query needs to be realized without consolidating all data into a single repository.