Get Started
Documentation
Languages
RUNNERS
Roadmap
Contribute
Community
Blog

Documentation
Using the Documentation
Pipeline development lifecycle
Beam programming guide
- Overview
- Pipelines
- PCollections
  - Creating a PCollection
  - PCollection characteristics
- Transforms
  - Applying transforms
  - Core Beam transforms
    - ParDo
    - GroupByKey
    - CoGroupByKey
    - Combine
    - Flatten
    - Partition
  - Requirements for user code
  - Side inputs
  - Additional outputs
  - Composite transforms
- Pipeline I/O
  - Using I/O transforms
  - Built-in I/O connectors
  - Developing new I/O connectors
  - Testing I/O transforms
- Data encoding and type safety
- Windowing
- Triggers
- Metrics
- State and Timers
Transform catalog
- Python
  - Overview
  - Element-wise
    - Filter
    - FlatMap
    - Keys
    - KvSwap
    - Map
    - ParDo
    - Partition
    - Regex
    - Reify
    - ToString
    - Values
    - WithTimestamps
  - Aggregation
    - CoGroupByKey
    - CombineGlobally
    - Count
    - Distinct
    - GroupByKey
    - Mean
    - Sample
    - Top
  - Other
    - Create
    - Flatten
    - Reshuffle
    - WindowInto
- Java
  - Overview
  - Element-wise
    - Filter
    - FlatMapElements
    - Keys
    - KvSwap
    - MapElements
    - ParDo
    - Partition
    - Regex
    - Reify
    - Values
    - ToString
    - WithKeys
    - WithTimestamps
  - Aggregation
    - ApproximateQuantiles
    - ApproximateUnique
    - CoGroupByKey
    - Combine
    - CombineWithContext
    - Count
    - Distinct
    - GroupByKey
    - GroupIntoBatches
    - HllCount
    - Latest
    - Max
    - Mean
    - Min
    - Sample
    - Sum
    - Top
  - Other
    - Create
    - Flatten
    - PAssert
    - View
    - Window
Common pipeline patterns
Runtime systems
Learning resources
Beam Wiki

Examples
Related transforms

Count

Counts the number of elements within each aggregation.

Examples

See BEAM-7390 for updates.

Related transforms

N/A

Start

Quickstart (Java)

Quickstart (Python)

Quickstart (Go)

Docs

Community

Resources

© The Apache Software Foundation | Privacy Policy | RSS Feed

Apache Beam, Apache, Beam, the Beam logo, and the Apache feather logo are either registered trademarks or trademarks of The Apache Software Foundation. All other products or name brands are trademarks of their respective holders, including The Apache Software Foundation.