Stage Reference Overview

Fluxion implements a large subset of MongoDB aggregation stages. Use this index to jump to detailed pages for each stage and discover related functionality.

Core Transformation Stages

$match: filter documents with MongoDB query semantics.
$project: reshape documents, include/exclude fields, compute expressions.
$addFields / $set: append or overwrite fields with aggregation expressions.
$unset: remove fields from documents.
$replaceRoot / $replaceWith: promote a sub-document to the root.
$limit and $skip: paginate documents flowing through the pipeline.
$sort and $sortByCount: reorder documents or tally counts by expression.
$unwind: explode arrays into individual documents.

Grouping & Bucketing

$group: group by _id and apply accumulators ($sum, $avg, etc.).
$bucket and $bucketAuto: bucket values using explicit boundaries or automatic distribution.
$facet: run multiple pipelines in parallel and merge the results.

Windowing & Time Series

$setWindowFields: apply window functions with partitioning and ordering.
$densify: fill gaps in time-series or sequence data.
$fill: carry forward or interpolate missing values.

Lookup & Integrations

$lookup: join with another collection or pipeline.

Advanced / Specialized

$merge, $out, $search, $vectorSearch: environment-specific stages with additional deployment prerequisites.
$sampleRate: probabilistic sampling using per-document Bernoulli draws.
$subPipeline: invoke child pipelines (sequential or parallel) and merge their outputs.

Use the sidebar for the full alphabetical list. Each stage page covers payload syntax, options, and representative examples you can drop into your pipelines.