DuneSQL: The 2023 Migration from Postgres to Trino/Iceberg

DuneSQL is the Trino-based query engine that has powered Dune Analytics since 2023, replacing the older Postgres-backed engine. The change was driven by scaling pressure: Postgres could not efficiently handle the data volumes generated by indexing dozens of blockchains, particularly for cross-chain queries and joins against large protocol tables. The migration introduced several breaking changes. DuneSQL is strict about type casting, so queries that worked implicitly on Postgres — for example comparing a timestamp column against a string literal like '2024-01-01' — suddenly required explicit casts. Complex queries with many JOINs frequently hit a 'too many stages' error, a consequence of the Trino query planner's stage limits. A migration tool called the Harmonizer attempted to automatically convert legacy Postgres-style queries to DuneSQL, but its coverage was imperfect, leaving top Wizards to manually rewrite hundreds of queries spread across dozens of dashboards. The transition was also a communications failure. Dune publicly acknowledged on multiple occasions that it under-communicated the timeline, deprecation policy, and migration path. Community frustration was substantial during 2023 and into early 2024. Resolution arrived through 2024. The stage limit roughly doubled from 500 to 1000, materialized views shipped in June 2024 to amortize expensive subqueries, and the Harmonizer improved. By late 2024 most actively maintained dashboards were DuneSQL-native, and the worst breakage was behind the platform. The lasting effect for new users is a steeper onboarding curve compared to the 2021-2022 era. Tutorials, dashboards, and forum answers written before 2023 often reference Postgres syntax that no longer works. Anyone learning the platform fresh should treat pre-2023 documentation as outdated and rely on current Dune docs that target DuneSQL directly. The underlying architecture is a Trino fork executing against tables stored in Apache Iceberg format. This is a common modern data-warehouse stack and makes Dune's data layer interoperable with standard analytics tooling — a property Dune later exploited when launching its dbt connector in November 2025.