Reviewed by Aditya Kumar · Last reviewed 2026-03-24
**map()**: One element → one output; row-level. Higher overhead per record. **mapPartitions()**: One partition (iterator) → iterator; enables setup/teardown per partition (e.g., DB connection); amortizes cost. **Use mapPartitions when**: DB connections, batch writes,...
map(): One element → one output; row-level. Higher overhead per record. mapPartitions(): One partition (iterator) → iterator; enables setup/teardown per partition (e.g., DB connection); amortizes cost. Use mapPartitions when: DB connections, batch writes, per-partition setup. Scalability: mapPartitions reduces function call overhead; avoids creating connection per row. Cost: mapPartitions = fewer tasks; map = fine-grained but expensive for I/O.
Red Flag: Creating DB connections in map()—connection per row. Pro-Move: 'mapPartitions for JDBC write; one connection per partition.'
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