🧠 Glossary

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📦 Key Concepts

Pipeline
A series of stages executed in order for each document. In Fluxion Core the focus is currently on single-document transformations (fan-out writes are on the roadmap).

Stage
A pipeline step (e.g., $match, $group, $project) that transforms documents.

Operator
An expression keyword like $sum, $map, $add, used inside stages.

Accumulator
Operators like $sum, $avg, $min, $max used within $group.

System Variables
- $$ROOT: The entire document. - $$CURRENT: The current level of the document. - $$NOW: Current timestamp. - $$REMOVE: Removes a field from projection. - $$CLUSTER_TIME: Simulated logical timestamp.

Executor
PipelineExecutor – the Java entry point that evaluates stages and expressions.

Expression
Any logic within fields: computations, filters, conditions.

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🧱 Stage & Operator Catalogues

See the Stages and Operators references for the up-to-date catalogues, syntax, and examples. Stages such as $merge, $out, $search, and $vectorSearch are reserved but not supported in Fluxion Core yet.