{"id":"mapreduce-materializes-at-phase-boundaries","text":"MapReduce in `mapreduce.py` writes intermediate data to JSON partition files between map and reduce phases, creating a full materialization barrier that prevents streaming from mapper to reducer","truth_value":"IN","source":"entries/2026/05/29/topic-ddia-chapter-10-batch-processing.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"explanation":{"steps":[{"node":"mapreduce-materializes-at-phase-boundaries","truth_value":"IN","reason":"premise"}]}}