Cheatsheet: PCollection

Topic Overview

Understand the core data container, its types, and state representations.

Syntax Snapshot

import apache_beam as beam

# PCollections are generated as outputs of reads or transforms
inputs = p | "Create Elements" >> beam.Create([1, 2, 3, 4])

# PCollections are immutable; each transform yields a new instance
evens = inputs | "Filter Evens" >> beam.Filter(lambda x: x % 2 == 0)

Key Points

• Immutable: Elements inside a PCollection cannot be modified in-place.
• Distributed: Data elements are split across VM workers in a cluster.
• Bounded (fixed size, batch processing) vs Unbounded (infinite size, streaming data).
• Schema-aware: Enforces structured types (like named tuples) for optimized SQL/join operations.

Production Recommendations