Debunking 8 data layout myths: why Liquid Clustering outperforms partitioning
Summary
Databricks' Liquid Clustering, generally available since 2024, is presented as a modern data layout standard for Lakehouses, outperforming traditional Hive-style partitioning. Partitioning often leads to over-partitioning and small-file problems in over 75% of cases, requiring table rewrites. Liquid Clustering uses clustering keys to guide optimal file organization, allowing keys to change and layouts to evolve without rewrites. It offers benefits like better skew handling, row-level concurrency, and multi-dimensional clustering. The article debunks eight myths, demonstrating Liquid Clustering provides 35% lower clustering time and 22% faster queries for low-cardinality columns, 90% faster metadata-only DELETEs, and 27x speedups for aggregate queries. It scales to petabytes, with OPTIMIZE planning time reduced from 12 hours to 23 minutes on 10 PB tables. Success stories include Arctic Wolf achieving 7.7x query speedup on a 3.8 PB table and Bolt seeing 138% write throughput increase. Upcoming features include co-clustered joins (51% faster) and easier in-place conversion.
Key takeaway
For Data Engineers or AI Architects managing large-scale Lakehouse data, if you are still relying on Hive-style partitioning, consider migrating to Liquid Clustering. Your current partitioning strategy likely causes small-file problems and suboptimal query performance in over 75% of cases. Adopting Liquid Clustering can significantly improve query speeds, reduce storage costs by up to 27%, and enhance write throughput by 138%, while simplifying data layout management and enabling row-level concurrency for ETL. Explore the `CLUSTER BY AUTO` option for intelligent key selection.
Key insights
Liquid Clustering provides a flexible, performant, and scalable data layout for modern Lakehouses, overcoming partitioning's limitations.
Principles
- Data layout should be an engine implementation detail.
- Clustering keys guide optimal file organization.
- Row-level concurrency removes write boundary needs.
Method
Create tables using "CLUSTER BY (col1, col2)" or "CLUSTER BY AUTO". Convert partitioned tables in-place with "ALTER TABLE .. REPLACE PARTITIONED BY WITH CLUSTER BY".
In practice
- Migrate 3.8 PB security telemetry tables for 7.7x query speedup.
- Improve CDC table write throughput by 138%.
- Reduce 1.1 PB table size by 27% and achieve 5.9x query speedup.
Topics
- Liquid Clustering
- Data Lakehouse
- Data Partitioning
- Delta Lake
- Apache Iceberg
- Data Optimization
- ETL Workloads
Best for: Data Engineer, MLOps Engineer, AI Architect
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Editorial summary, takeaway, and curation by AIssential. Original article published by Databricks.