--- title: Quack: DuckDB's new client-server protocol for... description: DuckDB Labs has released Quack, a new client-server protocol shipping as a core extension in DuckDB v1.5.3. It solves DuckDB's single-writer limitation by... canonical: https://daily.dev/posts/quack-duckdb-s-new-client-server-protocol-for-concurrent-writes-and-bulk-transfers-af6u3hqtf twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Quack: DuckDB's new client-server protocol for concurrent writes and bulk transfers | daily.dev og:description: DuckDB Labs has released Quack, a new client-server protocol shipping as a core extension in DuckDB v1.5.3. It solves DuckDB's single-writer limitation by... og:url: https://daily.dev/posts/quack-duckdb-s-new-client-server-protocol-for-concurrent-writes-and-bulk-transfers-af6u3hqtf og:image: https://api.daily.dev/og/posts/aF6u3HQtF.png og:image:alt: Quack: DuckDB's new client-server protocol for concurrent writes and bulk transfers og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Quack: DuckDB's new client-server protocol for concurrent writes and bulk transfers **[Collections](https://daily.dev/sources/collections)** · 3 min read · 2 upvotes · 0 comments ## Summary DuckDB Labs has released Quack, a new client-server protocol shipping as a core extension in DuckDB v1.5.3. It solves DuckDB's single-writer limitation by routing writes through a server process, enabling multiple instances to read and write concurrently over HTTP using DuckDB's internal serialization format. Benchmarks show 60 million rows transferred in under 5 seconds, outperforming PostgreSQL and Arrow Flight SQL for bulk transfers. The current security model is basic (shared token auth, no HTTPS by default, localhost-only binding), making it suitable for internal tooling but not multi-tenant production use yet. v1.5.3 also adds AWS web_identity chain support, Iceberg MERGE INTO and partitioned table writes, and statically linked jemalloc on Linux. A production release is planned alongside DuckDB v2.0 in fall 2026, with MotherDuck planning to support Quack as an endpoint type with added enterprise features. ## Content DuckDB Labs has released Quack, a new client-server protocol for DuckDB that ships as a core extension in v1.5.3. It's a meaningful architectural addition for anyone who's hit DuckDB's single-writer limitation. ## What Quack does DuckDB is an in-process database, which means only one process can write to a database file at a time. Quack works around this by routing writes through a server process, letting multiple DuckDB instances read and write to the same database concurrently over HTTP. The protocol uses DuckDB's own internal serialization format (with a custom `application/duckdb` MIME type), which is why the bulk transfer benchmarks look good: 60 million rows in under 5 seconds, faster than both PostgreSQL and Arrow Flight SQL for bulk transfers. For small concurrent writes up to 8 threads, it also beats PostgreSQL. Quack runs on port 9494 by default and auto-installs on first use. Authentication uses random shared tokens, and by default it only binds to localhost. For internet-facing deployments, the recommendation is to put nginx in front of it. ## Current limitations The security model is basic: shared token authentication, no HTTPS by default, no per-user access control. It's fine for internal tooling or local development, but not ready for multi-tenant production use as-is. DuckLake already supports Quack as its catalog database, which is a useful integration if you're using DuckLake for lakehouse-style workflows. ## What's in v1.5.3 beyond Quack Despite being a patch release, 1.5.3 ships a few other notable changes: - The AWS extension gains `web_identity` chain support for IRSA and IAM authentication for RDS/Aurora PostgreSQL - The HTTPS extension now respects `HTTP_PROXY` for proxied environments - The Iceberg extension gets `MERGE INTO` support, `INSERT`/`UPDATE` on partitioned tables, `CTAS` via ADBC, `ALTER TABLE` support, `GEOMETRY` type support, and schema property management functions - On Linux, jemalloc is now statically linked into core DuckDB rather than shipped as a separate extension ## The road ahead A production release is planned alongside DuckDB v2.0 in fall 2026, with replication support and deeper DuckLake integration on the roadmap. MotherDuck, the cloud-hosted DuckDB service, has said it plans to support Quack as an endpoint type. Their pitch is that self-hosted Quack handles the basics, while MotherDuck layers on multi-user permissions, SSO, storage/compute separation, serverless scaling, and SLAs for teams that need more than a single-server setup. For most DuckDB users doing local analytics, none of this changes anything. But if you've been working around the single-writer constraint with workarounds or just avoiding concurrent writes entirely, Quack is worth a look. ## Similar posts on daily.dev - [DuckDB Quack: Client/Server Protocol over HTTP for Multi-User Analytics](https://daily.dev/posts/duckdb-quack-client-server-protocol-over-http-for-multi-user-analytics-kclxrezzv) · InfoQ · 1 upvotes · 0 comments --- Tags: [#duckdb](https://daily.dev/tags/duckdb) [View this post on daily.dev](https://daily.dev/posts/quack-duckdb-s-new-client-server-protocol-for-concurrent-writes-and-bulk-transfers-af6u3hqtf) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Quack: DuckDB's new client-server protocol for concurrent writes and bulk transfers","url":"https://daily.dev/posts/quack-duckdb-s-new-client-server-protocol-for-concurrent-writes-and-bulk-transfers-af6u3hqtf","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/quack-duckdb-s-new-client-server-protocol-for-concurrent-writes-and-bulk-transfers-af6u3hqtf"},"datePublished":"2026-05-13T17:28:34.907Z","dateModified":"2026-05-20T12:02:34.165Z","description":"DuckDB Labs has released Quack, a new client-server protocol shipping as a core extension in DuckDB v1.5.3. 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