Name: Servicex
Author: gordonwatts

Overview

Provide concise, correct func_adl query patterns for ServiceX on ATLAS xAOD, with best practices for selections, outputs, and deliver usage.

Workflow

Identify the dataset type and base query.
- Use FuncADLQueryPHYSLITE for PHYSLITE or OpenData.
- Use FuncADLQueryPHYS for PHYS or other derivations.
Build a top-level Select that gathers all required collections and singletons.
- Apply object-level filters with nested .Where inside this Select.
- Do not pick columns yet.
Apply event-level filtering with a top-level .Where after the collections Select.
Create a final top-level Select that returns a single dictionary of output columns.
- Convert units to standard LHC units (GeV, meters, etc.).
- Never return a nested dictionary.
Use deliver once with by default and appropriate dataset source(s).

Provide concise, correct func_adl query patterns for ServiceX on ATLAS xAOD, with best practices for selections, outputs, and deliver usage.

Identify the dataset type and base query.
- Use FuncADLQueryPHYSLITE for PHYSLITE or OpenData.
- Use FuncADLQueryPHYS for PHYS or other derivations.
Build a top-level Select that gathers all required collections and singletons.
- Apply object-level filters with nested .Where inside this Select.
- Do not pick columns yet.
Apply event-level filtering with a top-level .Where after the collections Select.
Create a final top-level Select that returns a single dictionary of output columns.
- Convert units to standard LHC units (GeV, meters, etc.).
- Never return a nested dictionary.
Use deliver once with by default and appropriate dataset source(s).