DuckDB 2.0 adds a server mode and async I/O, and files that 1.x cannot open
DuckDB 2.0.0 LTS, "Cinnamon Teal", is the project's biggest feature release, built from close to 20,000 commits since 1.5. A database file it writes will not open in any earlier version.
The release adds a Quack server protocol, background reads for Parquet and CSV, VARIANT with automatic shredding, and triggers. A new PEG parser is now the default, ICU is gone, and 2.0 is supported until at least October 2027.
One user reports shrinking 7 TB of Azure NDJSON logs to 2.5% of their size in Parquet in under two hours on a medium VM.
What changes in 2.0
The announcement leads with server mode: a Quack protocol, a quack extension, a CONNECT statement for switching to remote databases including PostgreSQL and MySQL, and -serve and -connect CLI flags. Asynchronous I/O speeds up queries on object storage. VARIANT is fully integrated with automatic shredding of semi-structured data. An agent mode formats CLI output for coding agents and cut what the model had to read by 59% in TPC-H experiments. BEFORE and AFTER triggers arrive with row and statement scopes.
The breaking changes matter more than the list suggests. Versions before 2.0 cannot read files created by 2.0. The old parser is replaced by the PEG parser, available through a legacy_parser extension. A C++17 compiler is required, ICU is removed, and single-arrow lambdas are off by default and removed in 2.1.
| Release | Supported until |
|---|---|
| DuckDB 2.0 LTS | at least October 2027 |
| DuckDB 1.5 | March 2027 |
| DuckDB 1.4 LTS | late November 2026 |
Users: more cores, and a log archive
"Much more likely to see 100% utilisation up to about 128vCPUs or 192vCPUs, and that CPU usage to translate into workloads completing faster." — a data engineer running DuckDB on EC2
Before 2.0, he adds, speed topped out nearer 64 vCPUs. Another report was about storage.
"I just used DuckDB 2.0 last week to compress 7 terabytes of Azure logs (NDJSON) to 2.5% of the original size in Parquet format in under two hours with a medium sized VM!" — an admin who archived Azure logs
Quack is still young. A developer running the alpha in production built a Postgres wire protocol extension because "client support for Quack is very limited right now".
Teams on 1.4 LTS have until late November 2026, and any tool that reads a shared .duckdb file must be upgraded in step with the writer, or it will stop opening that file.
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