A few years ago the question about Apache Iceberg was whether open table formats could replace proprietary warehouses. That question is closed. Iceberg won. The new question is sharper and more interesting. What do we do with it next?
That is the question driving Iceberg v4.
At Iceberg Summit 2026 in San Francisco, more than 600 people gathered for two days and over 70 sessions. Not one talk tried to convince the room to adopt Iceberg. Every session assumed you already run it in production. The energy went somewhere else. It went to the limitations that success created, and to the spec changes that fix them.
This post walks through the state of v4 as of June 2026. It covers each major proposal, how the proposal works at a technical level, and why it matters for the people who run Iceberg at scale. It also covers the live debates, since v4 is not finished and the arguments on the dev list tell you as much as the design documents do.
Where v4 stands today
