Show HN: SerenDB – A Neon PostgreSQL fork optimized for AI agent workloads

SerenDB is a serverless open-source alternative to AWS Aurora Postgres. It separates storage and compute and substitutes the PostgreSQL storage layer by redistributing data across a cluster of nodes.

Try the SerenDB Free Tier to create a serverless Postgres instance. Then connect to it with your preferred Postgres client (psql, dbeaver, etc) or use the online SQL Editor. See Connect from any application for connection instructions.

Alternatively, compile and run the project locally.

A SerenDB installation consists of compute nodes and the SerenDB storage engine. Compute nodes are stateless PostgreSQL nodes backed by the SerenDB storage engine.

The SerenDB storage engine consists of two major components:

• Pageserver: Scalable storage backend for the compute nodes.
• Safekeepers: The safekeepers form a redundant WAL service that received WAL from the compute node, and stores it durably until it has been processed by the pageserver and uploaded to cloud storage.

See developer documentation in SUMMARY.md for more information.

SerenDB can be run on a workstation for small experiments and to test code changes, by following these instructions.

1. Install build dependencies and other applicable packages

• On Ubuntu or Debian, this set of packages should be sufficient to build the code:

• On Fedora, these packages are needed:

• On Arch based systems, these packages are needed:

Building SerenDB requires 3.15+ version of protoc (protobuf-compiler). If your distribution provides an older version, you can install a newer version from here.

2. Install Rust

1. Install XCode and dependencies

If you get errors about missing m4 you may have to install it manually:

2. Install Rust

3. Install PostgreSQL Client

The project uses rust toolchain file to define the version it's built with in CI for testing and local builds.

This file is automatically picked up by rustup that installs (if absent) and uses the toolchain version pinned in the file.

rustup users who want to build with another toolchain can use the rustup override command to set a specific toolchain for the project's directory.

non-rustup users most probably are not getting the same toolchain automatically from the file, so are responsible to manually verify that their toolchain matches the version in the file. Newer rustc versions most probably will work fine, yet older ones might not be supported due to some new features used by the project or the crates.

1. Build SerenDB and patched postgres

1. Build SerenDB and patched postgres

To run the psql client, install the postgresql-client package or modify PATH and LD_LIBRARY_PATH to include pg_install/bin and pg_install/lib, respectively.

To run the integration tests or Python scripts (not required to use the code), install Python (3.11 or higher), and install the python3 packages using ./scripts/pysync (requires poetry>=1.8) in the project directory.

1. Start pageserver and postgres on top of it (should be called from repo root):

2. Now, it is possible to connect to postgres and run some queries:

3. And create branches and run postgres on them:

4. If you want to run tests afterwards (see below), you must stop all the running pageserver, safekeeper, and postgres instances you have just started. You can terminate them all with one command:

More advanced usages can be found at Local Development Control Plane (serendb_local)).

If you encounter errors during setting up the initial tenant, it's best to stop everything (cargo serendb stop) and remove the .serendb directory. Then fix the problems, and start the setup again.

We are using cargo-nextest to run the tests in Github Workflows. Some crates do not support running plain cargo test anymore, prefer cargo nextest run instead. You can install cargo-nextest with cargo install cargo-nextest.

Ensure your dependencies are installed as described here.

By default, this runs both debug and release modes, and all supported postgres versions. When testing locally, it is convenient to run just one set of permutations, like this:

You may find yourself in need of flamegraphs for software in this repository. You can use flamegraph-rs or the original flamegraph.pl. Your choice!

For cleaning up the source tree from build artifacts, run make clean in the source directory.

For removing every artifact from build and configure steps, run make distclean, and also consider removing the cargo binaries in the target directory, as well as the database in the .serendb directory. Note that removing the .serendb directory will remove your database, with all data in it. You have been warned!

docs Contains a top-level overview of all available markdown documentation.

• sourcetree.md contains overview of source tree layout.

To view your rustdoc documentation in a browser, try running cargo doc --no-deps --open

See also README files in some source directories, and rustdoc style documentation comments.

Other resources:

• SELECT 'Hello, World': Blog post by Nikita Shamgunov on the high level architecture
• Architecture decisions in SerenDB: Blog post by Heikki Linnakangas
• SerenDB: Serverless PostgreSQL!: Presentation on storage system by Heikki Linnakangas in the CMU Database Group seminar series

Due to SerenDB's very close relation with PostgreSQL internals, numerous specific terms are used. The same applies to certain spelling: i.e. we use MB to denote 1024 * 1024 bytes, while MiB would be technically more correct, it's inconsistent with what PostgreSQL code and its documentation use.

To get more familiar with this aspect, refer to:

• SerenDB glossary
• PostgreSQL glossary
• Other PostgreSQL documentation and sources (SerenDB fork sources can be found here)

• Read CONTRIBUTING.md to learn about project code style and practices.
• To get familiar with a source tree layout, use sourcetree.md.
• To learn more about PostgreSQL internals, check http://www.interdb.jp/pg/index.html