Trino Python client

A Trino client for the Python programming language. It supports Python>=3.7 and pypy.

Usage

The Python Database API (DBAPI)

Installation

$ pip install trino

Quick Start

Use the DBAPI interface to query Trino:

from trino.dbapi import connect

conn = connect(
    host="<host>",
    port=<port>,
    user="<username>",
    catalog="<catalog>",
    schema="<schema>",
)
cur = conn.cursor()
cur.execute("SELECT * FROM system.runtime.nodes")
rows = cur.fetchall()

This will query the system.runtime.nodes system tables that shows the nodes in the Trino cluster.

The DBAPI implementation in trino.dbapi provides methods to retrieve fewer rows for example Cursor.fetchone() or Cursor.fetchmany(). By default Cursor.fetchmany() fetches one row. Please set trino.dbapi.Cursor.arraysize accordingly.

SQLAlchemy

Prerequisite

• Trino server >= 351

Installation

$ pip install trino[sqlalchemy]

Usage

To connect to Trino using SQLAlchemy, use a connection string (URL) following this pattern:

trino://<username>:<password>@<host>:<port>/<catalog>/<schema>

NOTE: password and schema are optional

Examples:

from sqlalchemy import create_engine
from sqlalchemy.schema import Table, MetaData
from sqlalchemy.sql.expression import select, text

engine = create_engine('trino://user@localhost:8080/system')
connection = engine.connect()

rows = connection.execute(text("SELECT * FROM runtime.nodes")).fetchall()

# or using SQLAlchemy schema
nodes = Table(
    'nodes',
    MetaData(schema='runtime'),
    autoload=True,
    autoload_with=engine
)
rows = connection.execute(select(nodes)).fetchall()

In order to pass additional connection attributes use connect_args method. Attributes can also be passed in the connection string.

from sqlalchemy import create_engine

engine = create_engine(
    'trino://user@localhost:8080/system',
    connect_args={
      "session_properties": {'query_max_run_time': '1d'},
      "client_tags": ["tag1", "tag2"],
      "experimental_python_types": True,
    }
)

# or in connection string
engine = create_engine(
    'trino://user@localhost:8080/system?'
    'session_properties={"query_max_run_time": "1d"}'
    '&client_tags=["tag1", "tag2"]'
    '&experimental_python_types=true',
)

Authentication mechanisms

Basic authentication

The BasicAuthentication class can be used to connect to a Trino cluster configured with the Password file, LDAP or Salesforce authentication type:

• DBAPI

  from trino.dbapi import connect
  from trino.auth import BasicAuthentication
  
  conn = connect(
      user="<username>",
      auth=BasicAuthentication("<username>", "<password>"),
      http_scheme="https",
      ...
  )

• SQLAlchemy

  from sqlalchemy import create_engine
  
  engine = create_engine("trino://<username>:<password>@<host>:<port>/<catalog>")
  
  # or as connect_args
  from trino.auth import BasicAuthentication
  engine = create_engine(
      "trino://<username>@<host>:<port>/<catalog>",
      connect_args={
          "auth": BasicAuthentication("<username>", "<password>"),
          "http_scheme": "https",
      }
  )

JWT authentication

The JWTAuthentication class can be used to connect to a Trino cluster configured with the JWT authentication type:

• DBAPI

  from trino.dbapi import connect
  from trino.auth import JWTAuthentication
  
  conn = connect(
      user="<username>",
      auth=JWTAuthentication("<jwt_token>"),
      http_scheme="https",
      ...
  )

• SQLAlchemy

  from sqlalchemy import create_engine
  
  engine = create_engine("trino://<username>@<host>:<port>/<catalog>/<schema>?access_token=<jwt_token>")
  
  # or as connect_args
  from trino.auth import JWTAuthentication
  engine = create_engine(
      "trino://<username>@<host>:<port>/<catalog>",
      connect_args={
          "auth": JWTAuthentication("<jwt_token>"),
          "http_scheme": "https",
      }
  )

OAuth2 authentication

The OAuth2Authentication class can be used to connect to a Trino cluster configured with the OAuth2 authentication type.

A callback to handle the redirect url can be provided via param redirect_auth_url_handler of the trino.auth.OAuth2Authentication class. By default, it will try to launch a web browser (trino.auth.WebBrowserRedirectHandler) to go through the authentication flow and output the redirect url to stdout (trino.auth.ConsoleRedirectHandler). Multiple redirect handlers are combined using the trino.auth.CompositeRedirectHandler class.

The OAuth2 token will be cached either per trino.auth.OAuth2Authentication instance or, when keyring is installed, it will be cached within a secure backend (MacOS keychain, Windows credential locker, etc) under a key including host of the Trino connection. Keyring can be installed using pip install 'trino[external-authentication-token-cache]'.

• DBAPI

  from trino.dbapi import connect
  from trino.auth import OAuth2Authentication
  
  conn = connect(
      user="<username>",
      auth=OAuth2Authentication(),
      http_scheme="https",
      ...
  )

• SQLAlchemy

  from sqlalchemy import create_engine
  from trino.auth import OAuth2Authentication
  
  engine = create_engine(
  "trino://<username>@<host>:<port>/<catalog>",
      connect_args={
          "auth": OAuth2Authentication(),
          "http_scheme": "https",
      }
  )

Certificate authentication

CertificateAuthentication class can be used to connect to Trino cluster configured with certificate based authentication. CertificateAuthentication requires paths to a valid client certificate and private key.

• DBAPI

  from trino.dbapi import connect
  from trino.auth import CertificateAuthentication
  
  conn = connect(
      user="<username>",
      auth=CertificateAuthentication("/path/to/cert.pem", "/path/to/key.pem"),
      http_scheme="https",
      ...
  )

• SQLAlchemy

  from sqlalchemy import create_engine
  from trino.auth import CertificateAuthentication
  
  engine = create_engine("trino://<username>@<host>:<port>/<catalog>/<schema>?cert=<cert>&key=<key>")
  
  # or as connect_args
  engine = create_engine(
  "trino://<username>@<host>:<port>/<catalog>",
      connect_args={
          "auth": CertificateAuthentication("/path/to/cert.pem", "/path/to/key.pem"),
          "http_scheme": "https",
      }
  )

Kerberos authentication

The KerberosAuthentication class can be used to connect to a Trino cluster configured with the Kerberos authentication type:

• DBAPI

  from trino.dbapi import connect
  from trino.auth import KerberosAuthentication
  
  conn = connect(
      user="<username>",
      auth=KerberosAuthentication(...),
      http_scheme="https",
      ...
  )

• SQLAlchemy

  from sqlalchemy import create_engine
  from trino.auth import KerberosAuthentication
  
  engine = create_engine(
      "trino://<username>@<host>:<port>/<catalog>",
      connect_args={
          "auth": KerberosAuthentication(...),
          "http_scheme": "https",
      }
  )

User impersonation

In the case where user who submits the query is not the same as user who authenticates to Trino server (e.g in Superset), you can set username to be different from principal_id. Note that principal_id is extracted from auth, for example username in BasicAuthentication, sub in JWT token or service-name in KerberosAuthentication. You need to make sure that principal_id has permission to impersonate username.

Extra credentials

Extra credentials can be sent as:

import trino
conn = trino.dbapi.connect(
    host='localhost',
    port=443,
    user='the-user',
    extra_credential=[('a.username', 'bar'), ('a.password', 'foo')],
)

cur = conn.cursor()
cur.execute('SELECT * FROM system.runtime.nodes')
rows = cur.fetchall()

SSL

SSL verification

In order to disable SSL verification, set the verify parameter to False.

from trino.dbapi import connect
from trino.auth import BasicAuthentication

conn = connect(
    user="<username>",
    auth=BasicAuthentication("<username>", "<password>"),
    http_scheme="https",
    verify=False
)

Self-signed certificates

To use self-signed certificates, specify a path to the certificate in verify parameter. More details can be found in the Python requests library documentation.

from trino.dbapi import connect
from trino.auth import BasicAuthentication

conn = connect(
    user="<username>",
    auth=BasicAuthentication("<username>", "<password>"),
    http_scheme="https",
    verify="/path/to/cert.crt"
)

Transactions

The client runs by default in autocommit mode. To enable transactions, set isolation_level to a value different than IsolationLevel.AUTOCOMMIT:

from trino.dbapi import connect
from trino.transaction import IsolationLevel

with connect(
        isolation_level=IsolationLevel.REPEATABLE_READ,
        ...
) as conn:
    cur = conn.cursor()
    cur.execute('INSERT INTO sometable VALUES (1, 2, 3)')
    cur.fetchall()
    cur.execute('INSERT INTO sometable VALUES (4, 5, 6)')
    cur.fetchall()

The transaction is created when the first SQL statement is executed. trino.dbapi.Connection.commit() will be automatically called when the code exits the with context and the queries succeed, otherwise trino.dbapi.Connection.rollback() will be called.

Improved Python types

If you enable the flag experimental_python_types, the client will convert the results of the query to the corresponding Python types. For example, if the query returns a DECIMAL column, the result will be a Decimal object.

Limitations of the Python types are described in the Python types documentation. These limitations will generate an exception trino.exceptions.DataError if the query returns a value that cannot be converted to the corresponding Python type.

import trino
import pytz
from datetime import datetime

conn = trino.dbapi.connect(
    experimental_python_types=True,
    ...
)

cur = conn.cursor()

params = datetime(2020, 1, 1, 16, 43, 22, 320000, tzinfo=pytz.timezone('America/Los_Angeles'))

cur.execute("SELECT ?", params=(params,))
rows = cur.fetchall()

assert rows[0][0] == params
assert cur.description[0][1] == "timestamp with time zone"

Development

Getting started with development

Start by forking the repository and then modify the code in your fork.

We recommend that you use Python3's venv for development:

$ python3 -m venv .venv
$ . .venv/bin/activate
$ pip install -e '.[tests]'

With -e passed to pip install above pip can reference the code you are modifying in the virtual env. That way, you do not need to run pip install again to make your changes applied to the virtual env.

When the code is ready, submit a Pull Request.

Code style

• For Python code, adhere to PEP 8.
• Prefer code that is readable over one that is "clever".
• When writing a Git commit message, follow these guidelines.

See also Trino's guidelines. Most of them also apply to code in trino-python-client.

Running tests

trino-python-client uses pytest for its tests. To run only unit tests, type:

$ pytest tests/unit

Then you can pass options like --pdb or anything supported by pytest --help.

To run integration tests:

$ pytest tests/integration

They pull a Docker image and then run a container with a Trino server:

• the image is named trinodb/trino:${TRINO_VERSION}
• the container is named trino-python-client-tests-{uuid4()[:7]}

To run the tests with different versions of Python in managed virtual envs, use tox (see the configuration in tox.ini):

$ tox

Releasing

• Set up your development environment.
• Check the local workspace is up to date and has no uncommitted changes

  git fetch -a && git status

• Change version in trino/__init__.py to a new version, e.g. 0.123.0.
• Commit

  git commit -a -m "Bump version to 0.123.0"

• Create an annotated tag

  git tag -m "" 0.123.0

• Create release package and upload it to PyPI

  . .venv/bin/activate && \
  pip install twine wheel setuptools && \
  rm -rf dist/ && \
  ./setup.py sdist bdist_wheel && \
  twine upload dist/* && \
  open https://pypi.org/project/trino/ && \
  echo "Released!"

• Push the branch and the tag

  git push upstream master 0.123.0

• Send release announcement on the #python-client channel on Trino Slack.

Need help?

Feel free to create an issue as it makes your request visible to other users and contributors.

If an interactive discussion would be better or if you just want to hangout and chat about the Trino Python client, you can join us on the #python-client channel on Trino Slack.