snowflake-emulator

A Snowflake emulator written in Rust for local development and testing. Built on DataFusion, compatible with Snowflake SQL API v2.

Quick Start

Using Docker

docker run -p 8080:8080 ghcr.io/sivchari/snowflake-emulator:latest

Building from source

cargo build --release --package server
./target/release/server

The server starts on localhost:8080.

Connecting with drivers

Use any Snowflake-compatible driver. Example with Go:

import "github.com/snowflakedb/gosnowflake"

cfg := &gosnowflake.Config{
    Account:   "emulator",
    User:      "user",
    Password:  "password",
    Host:      "localhost",
    Port:      8080,
    Protocol:  "http",
}

dsn, _ := gosnowflake.DSN(cfg)
db, _ := sql.Open("snowflake", dsn)

Supported SQL

Data Types

Type	Description
VARIANT	JSON-compatible dynamic type
ARRAY	JSON array
OBJECT	JSON object
Standard types	INT, DOUBLE, VARCHAR, BOOLEAN, DATE, TIMESTAMP

Snowflake-Specific Syntax

• LATERAL FLATTEN - Expand arrays/objects into rows
• QUALIFY - Filter window function results
• PIVOT / UNPIVOT - Transform rows to columns and vice versa
• MERGE INTO - Upsert operations
• COPY INTO - Load data from stages

Functions (90+)

Category	Examples
JSON	PARSE_JSON, GET, GET_PATH, OBJECT_KEYS
Array	ARRAY_CONSTRUCT, ARRAY_AGG, ARRAY_FLATTEN
Object	OBJECT_CONSTRUCT, OBJECT_INSERT, OBJECT_DELETE
Window	ROW_NUMBER, LAG, LEAD, CONDITIONAL_TRUE_EVENT
String	SPLIT, REGEXP_LIKE, REGEXP_REPLACE
Date	DATEADD, DATEDIFF, TO_TIMESTAMP
Conditional	IFF, NVL, NVL2, DECODE

DDL / DML

• CREATE/DROP DATABASE, CREATE/DROP SCHEMA
• CREATE/DROP TABLE, CREATE/DROP VIEW
• INSERT, UPDATE, DELETE, TRUNCATE
• BEGIN, COMMIT, ROLLBACK (transactions)
• SHOW TABLES, DESCRIBE, INFORMATION_SCHEMA

CI Usage

GitHub Actions

name: Test with Snowflake Emulator

on: [push, pull_request]

jobs:
  test:
    runs-on: ubuntu-latest

    services:
      snowflake:
        image: ghcr.io/sivchari/snowflake-emulator:latest
        ports:
          - 8080:8080

    steps:
      - uses: actions/checkout@v4

      - name: Run tests
        run: go test ./...
        env:
          SNOWFLAKE_HOST: localhost
          SNOWFLAKE_PORT: 8080
          SNOWFLAKE_PROTOCOL: http

Docker Compose

services:
  snowflake:
    image: ghcr.io/sivchari/snowflake-emulator:latest
    ports:
      - "8080:8080"

  app:
    build: .
    depends_on:
      - snowflake
    environment:
      SNOWFLAKE_HOST: snowflake
      SNOWFLAKE_PORT: 8080

testcontainers

container, _ := testcontainers.GenericContainer(ctx, testcontainers.GenericContainerRequest{
    ContainerRequest: testcontainers.ContainerRequest{
        Image:        "ghcr.io/sivchari/snowflake-emulator:latest",
        ExposedPorts: []string{"8080/tcp"},
        WaitingFor:   wait.ForHTTP("/health").WithPort("8080"),
    },
    Started: true,
})

Limitations

This emulator is designed for testing, not production use:

• No distributed execution (single-node only)
• No access control (GRANT/REVOKE are no-ops)
• No warehouse management
• Transaction isolation is not guaranteed

License

MIT