Handling Late-Arriving Duplicates via Watermarking

How can we deduplicate streaming events with dropDuplicates() while bounding memory with watermarks?

Advanced⏱ 3 Minutes⭐ 850 XP

🤔 THE QUESTION

How can we deduplicate streaming events with dropDuplicates() while bounding memory with watermarks?

💡 WHAT IS IT?

Combining withWatermark() and dropDuplicates(['event_id', 'event_time']) prunes old state after the watermark expires.

🎯 WHAT IS IT USED FOR?

Streaming event pipelines processing millions of mobile app click events with bounded cluster memory.

💻 EXAMPLE

df_deduped_stream = df.withWatermark("event_time", "2 hours").dropDuplicates(["event_id", "event_time"])

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