SQLAlchemy Trino Dialect

Warnings

• breaking The `sqlalchemy-trino` library is officially deprecated as of version 0.5.0. All active development has moved to the `trino-python-client` package, which now includes the SQLAlchemy dialect directly.
  Fix: Migrate your dependencies from `sqlalchemy-trino` to `trino[sqlalchemy]`. The connection string format remains `trino://...`.
• gotcha When `trino-python-client` (PyPI package `trino`) version 0.307.0 or newer is installed, it includes a built-in SQLAlchemy dialect. Installing both `sqlalchemy-trino` and `trino-python-client` might lead to conflicts or unexpected behavior if `sqlalchemy-trino` is older than 0.4.1.
  Fix: Upgrade `sqlalchemy-trino` to 0.4.1 or newer to avoid direct conflicts, or ideally, migrate to using only `trino[sqlalchemy]` and remove `sqlalchemy-trino`.
• breaking Version 0.4.0 introduced significant changes: `TrinoResultProxy` was removed in favor of eager-loading `cursor.description`, and metadata queries shifted from `SHOW` commands to `information_schema`.
  Fix: Code that relied on lazy loading of `cursor.description` or custom handling of `TrinoResultProxy` will need adjustment. Custom metadata queries might need to be rewritten to use `information_schema`.
• gotcha The default catalog was changed from `hive` to `system` in version 0.3.0.
  Fix: If your applications implicitly relied on `hive` as the default catalog without explicitly specifying it in the connection string, you will need to update your connection string to include `/hive` if that's still your desired catalog.

Install

• pip install sqlalchemy-trino Install deprecated library
• pip install trino[sqlalchemy] Recommended: Install official Trino client with SQLAlchemy support

Imports

• create_engine

  from sqlalchemy import create_engine

  The dialect is registered upon package installation; `create_engine` is used from `sqlalchemy` core.

Quickstart

Demonstrates how to connect to a Trino server using the `sqlalchemy-trino` dialect. It's crucial to note that this library is deprecated, and the recommended method is to use the `trino[sqlalchemy]` package directly, which provides the same dialect string (`trino://`).

import os
from sqlalchemy import create_engine, text

# NOTE: This library is DEPRECATED. The recommended approach is to use trino-python-client directly.
# pip install trino[sqlalchemy]
# from sqlalchemy import create_engine
# engine = create_engine(f"trino://{os.environ.get('TRINO_USER', 'user')}@{os.environ.get('TRINO_HOST', 'localhost')}:{os.environ.get('TRINO_PORT', '8080')}/{os.environ.get('TRINO_CATALOG', 'system')}/{os.environ.get('TRINO_SCHEMA', 'runtime')}")

# Example using the deprecated sqlalchemy-trino library:

# Configure connection details via environment variables or replace directly
TRINO_USER = os.environ.get('TRINO_USER', 'test_user')
TRINO_HOST = os.environ.get('TRINO_HOST', 'localhost')
TRINO_PORT = os.environ.get('TRINO_PORT', '8080')
TRINO_CATALOG = os.environ.get('TRINO_CATALOG', 'system')
TRINO_SCHEMA = os.environ.get('TRINO_SCHEMA', 'runtime')

connection_string = (
    f"trino://{TRINO_USER}@{TRINO_HOST}:{TRINO_PORT}/{TRINO_CATALOG}/{TRINO_SCHEMA}"
)

try:
    engine = create_engine(connection_string)
    with engine.connect() as connection:
        result = connection.execute(text("SELECT 1"))
        print("Successfully connected to Trino!")
        for row in result:
            print(row)
except Exception as e:
    print(f"Error connecting to Trino: {e}")
    print("Please ensure Trino is running and connection details are correct.")