Quack: The DuckDB Client-Server Protocol

294 points60 comments17 hours ago
steve_adams_86

I was just wishing something like this existed last week. What timing.

I'm piping sensor readings into duckdb with a deno server, and couldn't use duckdb -ui to look over the data without shutting down the server. I had no interest in using the server to allow me to look at the contents of the db, so I was just going to live with it for now. This perfectly solves that, along with several other similar kinds of problems I've encountered with duckdb.

duckdb is my favourite technology of 2025/26. It has worked its way into so many of my workflows. It's integral to how I work with LLMs, how I store all kinds of data, analytics, data pipelines... I love it.

rglover

This is rad. I've been eyeballing using DuckDB in my firm's internal app framework and this just solved the "but how do I horizontally scale this" problem. Kudos to the DuckDB folks. Love "Quack" for the protocol name, too.

simlevesque

I like DuckDB but I'm not sure what it wants to be. There's always new ways to use it and it's not easy to see what's the right one.

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feverzsj

They didn't explain what "concurrent writers" is. But seems it's just serialized writes on server side.

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smithclay

Been working on open-source projects involving storing and querying observability data (metrics, logs, traces) in parquet[0] and have been frustrated with the usability of Apache Iceberg … despite strongly agreeing and wanting to use an open storage format and catalog.

This makes Ducklake much more interesting for my use case, excited where this is going.

[0] https://github.com/smithclay/duckdb-otlp

microflash

This is fantastic. I’ve been building an Excel-like but columnar spreadsheet app using DuckDB and had to reinvent the “client” through classic HTTP layer.

NortySpock

Sounds useful for small-ball internal analytics datasets you want to place on shared team server.

I can definitely see exploring this for some homelab use.

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hermitcrab

I have a C++ application. Everything is in memory during execution. Saved to disk between session as XML. Works great, except that that it is strictly single user and some of my customers would love me to generalize it for multiple concurrent users reading and writing. Performance requirements are quite low - a few thousand records being updated by 2 or 3 people at a time. Would DuckDb + Quack be a good choice for this? Or are there better choices? I looked at SQLite, but I understand it doesn't operate as client server.

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mritchie712

> Can I use DuckDB with Quack as the catalog database for DuckLake?

> Not yet, but we are working on it!

Seems like a niche use case, but it's the one I'm most interested in.

Our lakehouse uses ducklake with postgres as the catalog. Seems like a DuckDB / Quack catalog would be an excellent alternative.

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hona_mind

The "what does DuckDB want to be" question keeps coming up, but I think the answer is already clear: it wants to be the SQLite of analytics. Embedded, zero-config, works everywhere. Quack is just the part that makes "everywhere" include remote.

ashkankiani

My first thought: setting up a self replicating duckdb wrapper over ssh so that I can execute queries on any computer. Can’t wait to play with this!

timsuchanek

This is very exciting. Now we just need this for Postgres as well.

ozgrakkurt

> It would be rather misguided not to build a database protocol on top of HTTP in 2026

This is wrong, HTTP is bad for transferring large amount of data and it is also bad for doing streaming.

It is bad for large amount of data because you have timeout issues on some clients, you hit request/response size limits etc.

It is obviously bad for streaming as there is no concept of streaming in it.

It is comical to go the path of least resistance so lazy people can put a reverse proxy on top of it. And then say HTTP is the only relevant way to do it in 2026.

The benchmark doesn't seem to mean much as TCP can max out 50GB/s on a single thread. Pretty sure it can do more than that even. So you could be using anything that isn't terrible and you should get max performance out of this.

Also the protocol is something else from the format. For example if you are transferring mp4 over ftp and http you can compare that.

If you are transferring different things over different protocols then the comparison means nothing.

The benchmark graph for bulk transfer should show more granularity so it is possible to understand how much of the % of the hardware limit it is reaching. Similar to how BLAS GEMM routines are benchmarked based on the % of theoretical max flops of the hardware.

> 60 million rows (76 GB in CSV format!)

This reads a bit disingenuous.

It is dissappointing to see this instead of something like PostgreSQL protocol with support for a columnar format.

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znite

Does this work with duckdb-wasm?

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Arcaveli

cool