Gold Lapel

Self-optimizing Postgres proxy — automatic materialized views and indexes. Zero code changes required.

Gold Lapel sits between your app and Postgres, watches query patterns, and automatically creates materialized views and indexes to make your database faster. Port 7932 (79 = atomic number for gold, 32 from Postgres).

gem install goldlapel

Or add to your Gemfile:

gem "goldlapel"

require "goldlapel"

# Start the proxy — returns a connection string pointing at Gold Lapel
url = GoldLapel.start("postgresql://user:pass@localhost:5432/mydb")

# Use the URL with any Postgres driver
require "pg"
conn = PG.connect(url)

# Or Sequel, ActiveRecord, ROM — anything that speaks Postgres

Gold Lapel is driver-agnostic. start returns a connection string (postgresql://...@localhost:7932/...) that works with any Postgres driver or ORM.

Starts the Gold Lapel proxy and returns the proxy connection string.

• upstream — your Postgres connection string (e.g. postgresql://user:pass@localhost:5432/mydb)
• port — proxy port (default: 7932)
• config — configuration hash (see Configuration below)
• extra_args — additional CLI flags passed to the binary (e.g. ["--threshold-impact", "5000"])

Stops the proxy. Also called automatically on process exit.

Returns the current proxy URL, or nil if not running.

Returns the dashboard URL (e.g. http://127.0.0.1:7933), or nil if not running. The dashboard port defaults to 7933 and can be configured via config: { dashboard_port: 9090 } or disabled with dashboard_port: 0.

Returns an array of all valid configuration key names (as strings).

Class interface for managing multiple instances:

proxy = GoldLapel::Proxy.new("postgresql://user:pass@localhost:5432/mydb", port: 7932)
url = proxy.start
# ...
proxy.stop

Pass a config hash to configure the proxy:

require "goldlapel"

url = GoldLapel.start("postgresql://user:pass@localhost/mydb", config: {
  mode: "butler",
  pool_size: 50,
  disable_matviews: true,
  replica: ["postgresql://user:pass@replica1/mydb"],
})

Keys use snake_case (symbols or strings) and map to CLI flags (pool_size -> --pool-size). Boolean keys are flags -- true enables them. Array keys produce repeated flags.

Unknown keys raise ArgumentError. To see all valid keys:

GoldLapel.config_keys

For the full configuration reference, see the main documentation.

You can also pass raw CLI flags via extra_args, or set environment variables (GOLDLAPEL_PORT, GOLDLAPEL_UPSTREAM, etc.) -- the binary reads them automatically.

This gem bundles the Gold Lapel Rust binary for your platform. When you call start, it:

1. Locates the binary (bundled in gem, on PATH, or via GOLDLAPEL_BINARY env var)
2. Spawns it as a subprocess listening on localhost
3. Waits for the port to be ready
4. Returns a connection string pointing at the proxy
5. Cleans up automatically on process exit

The binary does all the work — this wrapper just manages its lifecycle.

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