Apache Data Lakehouse Weekly: August 19 to 26, 2026

The lakehouse projects spent this week arguing about boundaries. Iceberg decided where conformance testing lives and started sketching the REST API shape that V4 tables will need. Polaris argued about what a committer owes a project when LLMs make pull requests cheap. Parquet pulled a feature apart because two proposals were reaching for the same mechanism. DataFusion and Iceberg Rust opened a joint thread about which repository should own their integration. Every one of those debates is a question about ownership, and the answers this week tell you a lot about how these communities plan to scale. Apache Iceberg The single biggest outcome of the week was the creation of a new repository. Neelesh Salian, working with Sung Yun and Andrei Tserakhau, called a vote to create apache/iceberg-verification , a standalone home for language-neutral conformance fixtures that every Iceberg implementation can run against. The vote passed with five binding +1s from Russell Spitzer, Sung Yun, Matt Topol, Daniel Weeks, and Amogh Jahagirdar, plus twenty-two non-binding votes. That is a wide turnout. The names on the non-binding list read like a roll call of the Rust, Python, Go, and Java maintainers, which is the point. Salian will now work with a PMC member to stand the repository up. The reason this matters goes beyond tidiness. Iceberg has at least five serious implementations today across Java, Python, Rust, Go, and C++. Each one carries its own test fixtures and its own understanding of edge cases in the spec. When two implementations disagree about how to interpret a manifest list, users find out the hard way. A shared set of fixtures that every implementation reads from one place turns spec ambiguity into a failing test rather than a production surprise. The 29 messages in the vote thread also included a fair amount of discussion about what belongs in the first batch of fixtures, and the conversation is worth reading if you maintain a client. The second major thread was about