Backfill
Retroactively populating a new data store, index, or column with historical data. Typically done as a batch job when adding a new feature that needs past data.
What is Backfill?
Retroactively populating a new data store, index, or column with historical data. Typically done as a batch job when adding a new feature that needs past data.
Backfill is a advanced concept that sits in the Stream & Batch Processing area of system design. Engineers reach for it whenever they need to reason about real-world trade-offs in that space — not just for textbook correctness, but because real production systems at companies like Netflix, Amazon, and Google make these decisions every day.
If you want to go deeper than this definition — with diagrams, code, and a quiz to lock it in — work through the "Backfill" lesson linked below. It walks through the why, the mechanism, the trade-offs, and how the giants actually use it in production.
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Full interactive lesson with diagrams, code examples, real-world references, and a quiz.
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Related glossary terms you might want to look up next.
Batch Processing
Processing large volumes of data in scheduled chunks rather than in real time. Think nightly reports, ETL jobs, and data warehouse loads.
ETL
Extract, Transform, Load: a pipeline that extracts data from sources, transforms it into the desired format, and loads it into a destination like a data warehouse.
Change Data Capture
Capturing row-level changes in a database and streaming them to other systems in real time. Debezium reads the write-ahead log and publishes changes to Kafka.