Apache Iceberg Dev List Digest: October 1–12, 2025
At the start of October 2025, the Apache Iceberg community focused intensely on architectural stability, particularly concerning the new REST Catalog specification, while coordinating broad advancements across multiple language bindings. This digest summarizes the major developments, status reports, and technical consensus reached during the first two weeks of the month.
Architectural Consensus: Securing the REST Catalog
The most strategic discussions focused on solidifying the governance and reliability features of the Iceberg REST Catalog, positioning it as the robust, standardized metadata control plane for the lakehouse ecosystem.
Fine-Grained Access Control (FGAC) Standardized
A critical step toward enterprise readiness was taken as the community reached consensus on the implementation of Fine-Grained Access Control (FGAC) within the REST catalog specification.
The proposal aims to provide an interoperable mechanism for query engines and Iceberg REST catalogs to enforce row- and column-level access control, including data masking. Steven Wu confirmed on October 1 that there was broad alignment on the chosen direction.
The consensus dictates that the “Iceberg Expressions + Iceberg UDFs way” will serve as the sole mechanism for retrieving protection instructions, aligning with the principle of separating policy definitions from protection instructions. This approach makes support for Iceberg expressions mandatory for catalogs and clients, ensuring that governance policies are portable and vendor-neutral across all compliant query engines, effectively solidifying the Iceberg specification as the universal contract for data governance.
Thread: Iceberg REST FGAC OpenAPI proposal
Enhancing Catalog Reliability and State Tracking
Progress was reported on two key features necessary for robust, cloud-native operation:
Idempotency: Work continued on adding idempotency tokens to REST mutation endpoints. This feature is vital for distributed environments, ensuring that clients retrying a failed operation (such as an updateTable call) do not cause data corruption or conflicts due to transient network failures, thereby guaranteeing transactional integrity.
Event Notifications: Consensus was reached on the design for the /events endpoint. This new endpoint is expected to enable clients and downstream services to subscribe to changes in table state — a fundamental requirement for modern change data capture (CDC) and data pipeline orchestration.
Thread: Iceberg REST FGAC OpenAPI proposal
Project Status: The October Board Report
On Wednesday, October 8, Ryan Blue circulated the initial draft of the monthly board report, providing a comprehensive snapshot of project health and technical achievements.
Governance and Progress Highlights
The report noted that the project status was “Ongoing” and, importantly, listed “Issues for the board: None,” indicating strong operational health.3 The community size stood at 35 committers and 21 PMC members.
Key project activities highlighted the aggressive pace of V4 specification development and ecosystem integration:
V4 Spec: Ongoing design progress for future features including relative paths, columnar statistics, Parquet metadata handling, and adaptive metadata tree proposals.
Java Core: Dedicated work to create an API for plugging in new file formats, and the commit of manifest list encryption for enhanced security.
Spark: Added support for Spark 4, including new features like row lineage metadata and variants.
Flink: The project successfully merged dynamic sink support, enabling transactional operations across multiple tables and managing schema evolution.3 Steven Wu, in a reply later that day, suggested adding support for Flink 2.0 to the update and correcting a typo from “dynamic sync” to the accurate “dynamic sink,” demonstrating the community’s proactive effort to ensure immediate compatibility with critical upcoming streaming ecosystem releases.
Multi-Language Client Advancement
The report detailed significant progress in language bindings, all actively working toward V3 feature parity:
Python (PyIceberg): Work continued on V3 implementation, integration with DataFusion, and adding support for writing to branches.
Rust: The Rust implementation was actively working on V3 features, including support for positional and equality deletes, and adding REST catalog loader and builder capabilities.
Go and C++: Go enabled Iceberg/Spark integration tests and added support for V3 manifests. C++ achieved its first 0.1.0 release in mid-September.
Thread: October board report
Client Milestones and Community Syncs
Iceberg Rust 0.7.0 Release
The development momentum in the Rust ecosystem culminated on Saturday, October 11, with the official announcement of the Apache Iceberg Rust 0.7.0 release.4 This milestone validates the strategic investment in non-JVM, high-performance clients necessary for integrating Iceberg with libraries like DataFusion and embedded applications.
Thread: [ANNOUNCE] Release Apache Iceberg Rust 0.7.0
Community Sync Meetings (Oct 1 amp; Oct 6)
Two critical community syncs were held during this period to resolve deep technical design questions:
Iceberg Catalog Community Sync (Oct 1): This meeting focused heavily on implementation details within the Java core. Key topics included the need to set a specific release cadence to better manage the process for future bug fix releases, and an ongoing discussion to refine and simplify the File Format API, particularly concerning the positional delete writer.5 This simplification effort directly supports reducing technical debt and accelerating V4 development.
Iceberg UDF Community Sync (Oct 6): This sync supported the “Ongoing collaboration on SQL UDF support” mentioned in the board report. UDF support is intrinsically linked to the FGAC consensus, as Iceberg Expressions and UDFs form the foundation for implementing portable security policies across catalogs.
Threads: Iceberg Catalog Community Sync Oct 1st 2025 , Iceberg UDF Community Sync Oct 6 2025
The overarching theme of the first half of October 2025 was Architectural Maturation and Strategic Unification. Discussions focused less on initial proposals and more on stabilizing the next generation of core components, specifically the REST Catalog and the V3/V4 feature roadmap.
The community achieved a crucial consensus on Fine-Grained Access Control (FGAC) using Iceberg Expressions, ensuring that governance is deeply integrated and interoperable across all clients utilizing the REST API. This focus on reliability (idempotency) and state tracking (the /events endpoint) cements the REST Catalog’s status as the mandatory metadata standard, decoupling Iceberg from legacy metastores.
Simultaneously, the language implementations demonstrated a coordinated march toward V3 feature parity, evidenced by the Rust 0.7.0 release and targeted updates in Python and Go. By prioritizing support for new engine versions (Spark 4, Flink 2.0 readiness) and integrating advanced governance features (row lineage metadata), the project is strategically positioning Iceberg to remain the feature-rich choice for high-performance, enterprise-secure lakehouse architecture. The work being done now is laying the stable foundation required for the ambitious V4 specification features currently under design.
Works cited
[Proposal] [REST] Fine Grained Access Control · Issue #14187 · apache/iceberg — GitHub, accessed October 13, 2025, https://github.com/apache/iceberg/issues/14187
[DISCUSS] Iceberg REST FGAC OpenAPI proposal-Apache Mail Archives, accessed October 13, 2025, https://lists.apache.org/thread/2jx33fn7lq37oxxm7sd6rjy0dnvbm4t6
[DISCUSS] October board report-Apache Mail Archives, accessed October 13, 2025, https://lists.apache.org/thread/rc4kw2kbtyco45otz94l4pys0sx3qndk
[ANNOUNCE] Release Apache Iceberg Rust 0.7.0-Apache Mail Archives, accessed October 13, 2025, https://lists.apache.org/thread/4kp9th9y1n2kdsc9zv1z120ytr6wg2w2
Iceberg Community Sync Aug 13 2025 — YouTube, accessed October 13, 2025,
Apache Iceberg dev list digest (Sept 8–12, 2025), accessed October 13, 2025, https://dev.to/alexmercedcoder/apache-iceberg-dev-list-digest-sept-8-12-2025-4cb5
Iceberg Catalog Community Sync Oct 1st 2025 — YouTube, accessed October 13, 2025,