Format Migration

Concepts: paTableFormats

What They Want to Hear 'Two approaches: in-place migration adds Iceberg metadata on top of existing Parquet files. Fast but limited: some features like Z-ordering require a full rewrite. For zero downtime, I use dual-write: write to both old and new format during a transition period, validate that queries produce identical results, switch reads to the new format, then decommission the old one.'