Data Engineered

  𝗗𝗲𝗹𝗲𝘁𝗶𝗻𝗴 𝟱 𝗿𝗼𝘄𝘀 𝗳𝗿𝗼𝗺 𝗮 𝟭 𝗯𝗶𝗹𝗹𝗶𝗼𝗻 𝗿𝗼𝘄 𝗗𝗲𝗹𝘁𝗮 𝘁𝗮𝗯𝗹𝗲 𝘀𝗵𝗼𝘂𝗹𝗱 𝗡𝗢𝗧 𝘁𝗮𝗸𝗲 𝟰𝟬 𝗺𝗶𝗻𝘂𝘁𝗲𝘀. 𝗕𝘂𝘁 𝗶𝘁 𝗱𝗼𝗲𝘀. 𝗔𝗻𝗱 𝗵𝗲𝗿𝗲'𝘀 𝗲𝘅𝗮𝗰𝘁𝗹𝘆 𝘄𝗵𝘆. ───────────────────── 𝗧𝗵𝗲 𝗣𝗿𝗼𝗯𝗹𝗲𝗺 ───────────────────── You have a 1 billion row Delta table. Business asks you to delete 5 incorrect customer records. You run: DELETE FROM customers WHERE customer_id IN ( ... ) Expected runtime: Seconds Actual runtime: 30+ Minutes Why? Because without Deletion Vectors, Delta must: → Read the entire parquet file → Remove the rows → Rewrite the entire file → Update the Delta log Even if you delete 1 row — the entire file is rewritten. That's millions of rows rewritten for just 5 deletes. Example: file1.parquet → 1,000,000 rows, 2 deleted file2.parquet → 900,000 rows, 1 deleted → Delta rewrites 1.9 million rows for 3 deletes. ───────────────────── 𝗧𝗵𝗲 𝗦𝗼𝗹𝘂𝘁𝗶𝗼𝗻: 𝗗𝗲𝗹𝗲𝘁𝗶𝗼𝗻 𝗩𝗲𝗰𝘁𝗼𝗿𝘀 ───────────────────── Instead of ...