DuckDB has released version 2.0.0 LTS, codenamed “Cinnamon Teal,” representing its largest feature release to date. According to the announcement, the release contains nearly 20,000 commits since version 1.5 and introduces substantial improvements across multiple areas.
The release establishes DuckDB as a server database for the first time. Previously in-process only, DuckDB 1.5.3 introduced the Quack protocol for client-server operation. Version 2.0.0 ships a polished version with performance and stability improvements, along with a new CONNECT statement that allows attaching and switching to remote databases in a single command. The protocol works through a quack extension that enables any DuckDB process to serve its databases. For security, the server listens only on localhost by default and should be placed behind a TLS-terminating reverse proxy for external connections. The CLI now includes -serve and -connect shortcuts for setting up Quack server-client pairs directly from the command line.
Asynchronous I/O emerges as a key performance enhancement. DuckDB 2.0 introduces async I/O for reading Parquet, CSV, and native storage formats. The I/O layer now scales independently from query processing, issuing reads in the background and maintaining multiple concurrent requests. This architecture dramatically improves performance on object storage like S3.
The VARIANT type, which stores semi-structured data like JSON while maintaining columnar execution performance, becomes fully integrated in 2.0. The system now detects common data structures and “shreds” them for improved compression and execution speed. Full end-to-end support extends from shredded storage execution through Parquet reading and writing, backed by variant_* functions.
Agent mode represents a new CLI feature targeting coding agents and AI models. When detected, the CLI switches to agent mode: outputting compact Markdown tables instead of padded boxes, clearly indicating truncated results, stopping runaway queries early, and reporting errors as JSON. Long-running queries report expected cost before execution. According to the announcement, agent mode reduced DuckDB output that models must process by 59% in TPC-H experiments.
The release includes a brand new PEG-based SQL parser replacing PostgreSQL-derived code used since 2018. The modern parser allows extensions to hook into grammar itself for entirely new SQL syntax support. It maintains compatibility with the legacy parser, which users can enable with SET enable_legacy_parser = true;.
DuckDB 2.0.0 is designated as a long-term support release with support until at least October 2027. The previous LTS version 1.4 remains supported until late November 2026, and 1.5 support extends to March 2027.
Key facts
- DuckDB 2.0.0 contains nearly 20,000 commits since version 1.5
- The Quack protocol enables client-server operation with new CONNECT statement for remote database attachment
- Asynchronous I/O for Parquet, CSV, and native formats dramatically improves performance on object storage
- VARIANT type fully integrated with structure detection and shredding for compression and speed
- Agent mode reduces model output processing by 59% in TPC-H tests
- New PEG-based SQL parser replaces PostgreSQL-derived parser; legacy parser available via extension
- LTS support runs until at least October 2027