{"id":9332,"library":"sqlalchemy-vertica-python","title":"SQLAlchemy Vertica Dialect (sqlalchemy-vertica-python)","description":"sqlalchemy-vertica-python is a Vertica dialect for SQLAlchemy that utilizes the pure-Python DB-API driver `vertica-python` for database connectivity. It is currently at version 0.6.3, actively maintained by BlueLabs, and typically releases updates to align with SQLAlchemy versions or address bugs.","status":"active","version":"0.6.3","language":"en","source_language":"en","source_url":"https://github.com/bluelabsio/sqlalchemy-vertica-python","tags":["SQLAlchemy","Vertica","database","dialect","analytics"],"install":[{"cmd":"pip install sqlalchemy-vertica-python","lang":"bash","label":"Install latest version"}],"dependencies":[{"reason":"Core dependency for database abstraction. Version 0.6.0+ is compatible with SQLAlchemy 2.0.","package":"sqlalchemy","optional":false},{"reason":"The underlying DB-API driver used by the dialect for Vertica connectivity. The dialect installation typically handles this dependency.","package":"vertica-python","optional":false}],"imports":[{"note":"The dialect is loaded implicitly via the connection string prefix.","symbol":"create_engine","correct":"from sqlalchemy import create_engine"}],"quickstart":{"code":"import os\nfrom sqlalchemy import create_engine, text\n\n# Environment variables for connection details (replace with your Vertica credentials)\nVERTICA_USER = os.environ.get('VERTICA_USER', 'dbadmin')\nVERTICA_PASSWORD = os.environ.get('VERTICA_PASSWORD', 'password')\nVERTICA_HOST = os.environ.get('VERTICA_HOST', 'localhost')\nVERTICA_PORT = os.environ.get('VERTICA_PORT', '5433')\nVERTICA_DB = os.environ.get('VERTICA_DB', 'VMart')\n\n# Construct the connection string\nconnection_string = (\n    f\"vertica+vertica_python://{VERTICA_USER}:{VERTICA_PASSWORD}\"\n    f\"@{VERTICA_HOST}:{VERTICA_PORT}/{VERTICA_DB}\"\n)\n\ntry:\n    # Create an engine instance\n    engine = create_engine(connection_string)\n\n    # Establish a connection\n    with engine.connect() as connection:\n        # Execute a simple query\n        result = connection.execute(text(\"SELECT version();\"))\n        \n        # Fetch and print the result\n        for row in result:\n            print(f\"Connected to Vertica. Version: {row[0]}\")\n\nexcept Exception as e:\n    print(f\"Error connecting to Vertica or executing query: {e}\")\n","lang":"python","description":"This quickstart demonstrates how to establish a connection to a Vertica database using `sqlalchemy-vertica-python` and execute a simple query to retrieve the database version. Ensure your Vertica instance is accessible and replace placeholder credentials with actual environment variables or direct values."},"warnings":[{"fix":"Review the SQLAlchemy 2.0 migration guide and update application code accordingly. For connection string usage, ensure `create_engine` is used. Consider pinning `sqlalchemy` to a 1.x version if immediate migration to 2.0 is not feasible with older dialect versions.","message":"Version 0.6.0 introduced a significant update to support SQLAlchemy 2.0 syntax. Projects using older versions of `sqlalchemy-vertica-python` (pre-0.6.0) with SQLAlchemy 1.x will need to migrate their code to be compatible with SQLAlchemy 2.0 practices if upgrading the dialect.","severity":"breaking","affected_versions":">=0.6.0"},{"fix":"Always use `with engine.connect() as connection:` to ensure connections are properly closed, or manually call `connection.close()` and `engine.dispose()` when managing connections manually.","message":"It is crucial to explicitly close database connections. After using `engine.connect()`, ensure `connection.close()` is called, followed by `engine.dispose()`. Failing to do so can lead to resource leaks as Python's garbage collector might remove resources before the Vertica connector properly closes the session.","severity":"gotcha","affected_versions":"All"},{"fix":"Be aware of potential limitations and ensure thorough testing in production environments. Consider contributing to the project for missing features.","message":"The PyPI project classifies its development status as '3 - Alpha'. This indicates that the library might still be evolving, features could be limited, and support may vary.","severity":"gotcha","affected_versions":"All"},{"fix":"Explicitly define the `dtype` mapping for string columns to `sqlalchemy.types.VARCHAR` when using `df.to_sql` to ensure correct type inference and prevent issues.","message":"When using `pandas.DataFrame.to_sql()` with `sqlalchemy-vertica-python`, there might be issues with `VARCHAR` columns if string variables are not explicitly cast. The dialect might default to `TEXT` which can cause problems.","severity":"gotcha","affected_versions":"All"}],"env_vars":null,"last_verified":"2026-04-16T00:00:00.000Z","next_check":"2026-07-15T00:00:00.000Z","problems":[{"fix":"Ensure `sqlalchemy-vertica-python` is installed (`pip install sqlalchemy-vertica-python`) and that your connection string correctly uses the `vertica+vertica_python` prefix, e.g., `create_engine('vertica+vertica_python://...')`.","cause":"This error typically indicates that the `sqlalchemy-vertica-python` package is either not installed correctly, or the dialect name in the connection string is incorrect, preventing SQLAlchemy from finding the registered dialect.","error":"NoSuchModuleError: Can't load plugin: sqlalchemy.dialects:python.vertica"},{"fix":"Verify the `host` and `port` in your connection string are correct. Check network connectivity, firewall rules on both client and server, and ensure the Vertica database is running and accessible from the client machine.","cause":"This error indicates that the Python application could not establish a TCP/IP connection to the Vertica database server. Common causes include incorrect host, port, firewall blocking, or the Vertica server not running or listening on the specified port.","error":"sqlalchemy.exc.OperationalError: (vertica_python.errors.ConnectionError) Connection failed: [Errno 111] Connection refused"},{"fix":"Double-check the `user` and `password` in your connection string. Ensure they match a valid Vertica user account and its credentials.","cause":"The username or password provided in the connection string is incorrect for the specified Vertica user.","error":"sqlalchemy.exc.ProgrammingError: (vertica_python.errors.QueryError) Password authentication failed for user 'your_user'"},{"fix":"Ensure the `con` parameter for `df.to_sql` is an SQLAlchemy `Engine` or `Connection` object, not a raw DBAPI connection. If the issue persists, explicitly define `schema` and `name` arguments for `to_sql` and specify `dtype` for columns.","cause":"This specific error often arises when `pandas.DataFrame.to_sql` attempts to introspect the schema using an SQLite-specific query, indicating a mismatch or misconfiguration in how the dialect interacts with `pandas`, or a misunderstanding of prepared statement placeholders by the underlying driver.","error":"ValueError: Invalid SQL: SELECT name FROM sqlite_master WHERE type IN ('table', 'view') AND name=?; HINT: When argument 'parameters' is a tuple/list, variables in SQL should be specified with positional format (%s) placeholders. Question mark (?) placeholders have to be used with use_prepared_statements=True setting."}]}