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Open Table Formats in the Wild: From Parquet to Delta Lake and Back

Talkat PyCon DE & PyData 2025 · on Wednesday, 2025-04-23· at 12:25· Zeiss Plenary (Spectrum)· [data-engineering, databases]
slides:none on file

Attempts to replace a Parquet bronze layer with Delta Lake hit three concrete surprises: a 1.3 TB compaction test shows liquid clustering cuts API calls and latency versus Hive-style partitions, but a 50 GB incremental ingestion flips results—liquid clustering becomes slower and requires an undocumented Databricks config to behave; interoperability tests reveal Delta Lake feature incompatibility with DuckDB, Polars and Pandas until table features are stripped; file-based session boundaries only work with Autoloader, plain Delta tables break session semantics.

AI-written summary · about

  1. 0:00Open table formats intro
  2. 1:55Why data matters
  3. 4:21Printing machine efficiency
  4. 7:29Big data platform evolution
  5. 12:46Parquet vs CSV/JSON
  6. 18:45Parquet limitations
  7. 20:28Delta Lake/Iceberg extend Parquet
  8. 25:25Testing Delta Lake
  9. 28:56Liquid clustering issues
  10. 31:26Delta Lake interoperability
  11. 33:52Session boundaries in Delta Lake
  12. 34:14Delta vs Iceberg communities
  13. 37:46Vendor lock-in reduction
  14. 38:50Q&A
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