orez

It's Zero and Postgres with no native dependencies in one package. Helped by a custom WASM fork of SQLite's bedrock branch called bedrock-sqlite. No Docker, no Postgres install, no node-gyp, no platform-specific binaries.

bunx orez

Starts PGlite (WASM Postgres), a TCP proxy, and zero-cache with WASM SQLite. Exports a CLI, programmatic API, and Vite plugin. Comes with PGlite extensions pgvector and pg_trgm enabled by default.

Install

bun install orez

CLI

bunx orez

--pg-port=6434            postgresql proxy port
--zero-port=5849          zero-cache port
--data-dir=.orez          data directory
--migrations=DIR          migrations directory (skipped if not set)
--seed=FILE               seed file path
--pg-user=user            postgresql user
--pg-password=password    postgresql password
--skip-zero-cache         run pglite + proxy only, skip zero-cache
--log-level=warn          error, warn, info, debug
--s3                      also start a local s3-compatible server
--s3-port=9200            s3 server port
--disable-wasm-sqlite     use native @rocicorp/zero-sqlite3 instead of wasm bedrock-sqlite
--on-db-ready=CMD         command to run after db+proxy are ready, before zero-cache starts
--on-healthy=CMD          command to run once all services are healthy

Ports auto-increment if already in use.

Programmatic

import { startZeroLite } from 'orez'

const { config, stop, db, instances } = await startZeroLite({
  pgPort: 6434,
  zeroPort: 5849,
  migrationsDir: 'src/database/migrations',
  seedFile: 'src/database/seed.sql',
})

// your app connects to zero-cache at localhost:5849
// database is at postgresql://user:password@localhost:6434/postgres

// db is the postgres PGlite instance (for direct queries)
// instances has all three: { postgres, cvr, cdb }

// when done
await stop()

All options are optional with sensible defaults. Ports auto-find if in use.

Vite plugin

import orez from 'orez/vite'

export default {
  plugins: [
    orez({
      pgPort: 6434,
      zeroPort: 5849,
      migrationsDir: 'src/database/migrations',
    }),
  ],
}

Starts orez when vite dev server starts, stops on close.

How it works

orez starts three things:

1. Three PGlite instances (full PostgreSQL 16 running in-process via WASM) — one for each database zero-cache expects (upstream, CVR, change)
2. A TCP proxy that speaks the PostgreSQL wire protocol, routing connections to the correct PGlite instance and handling logical replication
3. A zero-cache child process that connects to the proxy thinking it's a real Postgres server

Multi-instance architecture

zero-cache expects three separate databases: postgres (app data), zero_cvr (client view records), and zero_cdb (change-streamer state). In real PostgreSQL these are independent databases with separate connection pools and transaction contexts.

orez creates a separate PGlite instance for each database, each with its own data directory and mutex. This is critical because PGlite is single-session — all proxy connections to the same instance share one session. Without isolation, transactions on the CVR database get corrupted by queries on the postgres database (zero-cache's view-syncer detects this as ConcurrentModificationException and crashes). Separate instances eliminate cross-database interference entirely.

The proxy routes connections based on the database name in the startup message:

Each instance has its own mutex for serializing queries. Extensions (pgvector, pg_trgm) and app migrations only run on the postgres instance.

Replication

zero-cache needs logical replication to stay in sync with the upstream database. PGlite doesn't support logical replication natively, so orez fakes it. Every mutation is captured by triggers into a changes table, then encoded into the pgoutput binary protocol and streamed to zero-cache through the replication connection. zero-cache can't tell the difference.

The replication handler also tracks shard schema tables (e.g., chat_0.clients, chat_0.mutations) that zero-cache creates for mutation state. These are monitored via change tracking triggers so that .server promises on zero mutations resolve correctly.

Zero native dependencies

The whole point of orez is that bunx orez works everywhere with no native compilation step. Postgres runs in-process as WASM via PGlite. But zero-cache also needs SQLite, and @rocicorp/zero-sqlite3 ships as a compiled C addon — which means node-gyp, build tools, and platform-specific binaries.

orez ships its own package, bedrock-sqlite — SQLite's bedrock branch recompiled to WASM with BEGIN CONCURRENT and WAL2 support. At startup, orez patches @rocicorp/zero-sqlite3 to load bedrock-sqlite instead of the native C addon. Both databases run as WASM — nothing to compile, nothing platform-specific. Just bun install and go.

Environment variables

Your entire environment is forwarded to the zero-cache child process. This means any ZERO_* env vars you set are passed through automatically.

orez provides sensible defaults for a few variables:

The --log-level flag controls both zero-cache (ZERO_LOG_LEVEL) and PGlite's debug output. Default is warn to keep output quiet. Set to info or debug for troubleshooting.

The layering is: orez defaults → your env → orez-managed connection vars. So setting ZERO_LOG_LEVEL=debug in your shell overrides the --log-level default, but you can't override the database connection strings (orez needs to point zero-cache at its own proxy).

Common vars you might want to set:

ZERO_MUTATE_URL=http://localhost:3000/api/zero/push
ZERO_QUERY_URL=http://localhost:3000/api/zero/pull

What gets faked

The proxy intercepts several things to convince zero-cache it's talking to a real PostgreSQL server with logical replication enabled:

• IDENTIFY_SYSTEM returns a fake system ID and timeline
• CREATE_REPLICATION_SLOT persists slot info in a local table and returns a valid LSN
• START_REPLICATION enters streaming mode, encoding changes as pgoutput binary messages
• current_setting('wal_level') always returns logical
• pg_replication_slots queries are redirected to a local tracking table
• SET TRANSACTION SNAPSHOT is silently accepted (PGlite doesn't support imported snapshots)
• ALTER ROLE ... REPLICATION returns success
• READ ONLY is stripped from transaction starts (PGlite is single-session)
• ISOLATION LEVEL is stripped from all queries (meaningless with a single-session database)
• SET TRANSACTION / SET SESSION return synthetic success without hitting PGlite

The pgoutput encoder produces spec-compliant binary messages: Begin, Relation, Insert, Update, Delete, Commit, and Keepalive. Column values are encoded as text (typeOid 25) except booleans which use typeOid 16 with t/f encoding, matching PostgreSQL's native boolean wire format.

Tests

141 tests — 104 orez tests across 7 test files covering the full stack from binary encoding to TCP-level integration, plus 37 bedrock-sqlite tests covering the WASM SQLite engine:

bun run test                                # orez tests
cd sqlite-wasm && bunx vitest run           # bedrock-sqlite tests

The orez test suite includes a zero-cache compatibility layer that decodes pgoutput messages into the same typed format that zero-cache's PgoutputParser produces, validating end-to-end compatibility.

The bedrock-sqlite tests cover Database/Statement API, transactions, WAL/WAL2 modes, BEGIN CONCURRENT, FTS5, JSON functions, custom functions, aggregates, bigint handling, and file persistence.

Limitations

This is a development tool. It is not suitable for production use.

• PGlite is single-session per instance. All queries to the same database are serialized through a mutex. Cross-database queries are independent (each database has its own PGlite instance and mutex). Fine for development but would bottleneck under real load.
• Triggers add overhead to every write. Again, fine for development.
• PGlite stores data on the local filesystem. No replication, no backups, no high availability.

Project structure

src/
  index.ts              main entry, orchestrates startup + sqlite wasm patching
  cli.ts                cli with citty
  config.ts             configuration with defaults
  log.ts                colored log prefixes
  mutex.ts              simple mutex for serializing pglite access
  port.ts               auto port finding
  pg-proxy.ts           tcp proxy with per-instance routing and query rewriting
  pglite-manager.ts     multi-instance pglite creation and migration runner
  s3-local.ts           local s3-compatible server (orez/s3)
  vite-plugin.ts        vite dev server plugin (orez/vite)
  replication/
    handler.ts          replication protocol state machine
    pgoutput-encoder.ts binary pgoutput message encoder
    change-tracker.ts   trigger installation, shard schema tracking, and change reader
sqlite-wasm/
  Makefile              emscripten build for bedrock-sqlite wasm binary
  bedrock-sqlite.d.ts   typescript declarations
  native/
    api.js              better-sqlite3 compatible database/statement API
    vfs.c               custom VFS with SHM support for WAL/WAL2
    vfs.js              javascript VFS bridge
  test/
    database.test.ts    37 tests for the wasm sqlite engine

Extra: orez/s3

Since we use this stack often with a file uploading service like MinIO which also requires docker, I threw in a tiny s3-compatible endpoint too:

bunx orez --s3 or standalone bunx orez s3.

import { startS3Local } from 'orez/s3'

const server = await startS3Local({
  port: 9200,
  dataDir: '.orez',
})

Handles GET, PUT, DELETE, HEAD with CORS. Files stored on disk. No multipart, no ACLs, no versioning.

License

MIT