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egres

Introduction

Egres is a Postgres-compatible database for heavy, multi-tenant workloads. Written in Zig, Egres isn’t just a Postgres rewrite: it is a ground-up, first principles redesign that speaks Postgres. Apart from libpg_query, it uses no Postgres code.

Egres:

  • Speaks the Postgres protocol. psql, drivers and ORM connect unchanged.
  • Can run thousands of tenants on one process. Queries run on a custom coroutine (fiber) system, with CPU ticks, memory and disk IOPS metered per query and per tenant.
  • Uses a new storage engine, called zdb, which is an LSM forest (tree of LSM trees) for storage, with block compression, checksums, multi-version concurrency control and garbage collection.
  • Runs on local disk or object storage. With S3, a node keeps only its WAL and an optional NVMe disk cache locally.
  • Provides Raft based replication, with read-your-write guarantees across any replica.
  • Provides instant database and table branching with zero copy and without doing copy-on-write.
  • Open Source under Apache 2.0.

This release v0.2610.x runs as a single node. The multi-node code is in but not enabled yet; that would land in the next release. Most of the work in this version went into storage, replication, resource metering and fiber based query execution. The query features are basic for now, equality-only and no joins, and will grow with each release.

Start here

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