SQLAlchemy Vertica Dialect

0.0.5 · maintenance · verified Fri Apr 17

SQLAlchemy-Vertica provides a dialect for connecting SQLAlchemy to Vertica databases, leveraging the `vertica-python` driver. It allows users to interact with Vertica using SQLAlchemy's ORM and SQL Expression Language. The current version is 0.0.5, and the project appears to be in maintenance mode with infrequent updates.

Common errors

```
sqlalchemy.exc.NoSuchModuleError: Can't load plugin: sqlalchemy.dialects:vertica.vertica_python
```
cause The `sqlalchemy-vertica` package (or its dependency `vertica-python`) is not installed or the Python environment is incorrect.

fix Ensure `pip install sqlalchemy-vertica` has been run in the active Python environment. Verify that `vertica-python` is also installed.
```
OperationalError: (vertica_python.errors.QueryError) failed to connect: [Errno 111] Connection refused
```
cause The Vertica database server is not reachable at the specified host and port, or is not running. This could be due to network issues, incorrect hostname/IP, or an inactive database.

fix Check the `VERTICA_HOST` and `VERTICA_PORT` in your connection string. Verify network connectivity to the Vertica server and ensure the server is running and accessible.
```
OperationalError: (vertica_python.errors.QueryError) Password authentication failed for user "your_user"
```
cause Incorrect username or password provided in the connection string.

fix Double-check the `VERTICA_USER` and `VERTICA_PASSWORD` in your connection string for accuracy.

Warnings

gotcha The `sqlalchemy-vertica` dialect has not been actively developed since 2021 (v0.0.5). It may not fully support newer features of SQLAlchemy (e.g., 2.0+ specific patterns) or be compatible with very recent Vertica database versions. Users should test thoroughly if using with latest SQLAlchemy or Vertica releases.
Fix: Review GitHub issues/PRs for similar problems or consider contributing fixes. Test against your specific SQLAlchemy and Vertica versions.
gotcha Vertica's specific data type behaviors, such as `TEXT` often behaving like `VARCHAR(MAX)` or character sets, might lead to unexpected mapping issues with SQLAlchemy's generic types. Explicit type casting or using `sqlalchemy.types.VARCHAR` with a length might be necessary.
Fix: For specific column definitions, explicitly define `sqlalchemy.types` (e.g., `Column('name', String(255))`) instead of relying solely on inferred types.
gotcha Vertica includes non-standard SQL constructs (e.g., `COPY` statements, `CREATE TABLE AS SELECT WITH NO DATA`). These are typically not directly supported by SQLAlchemy's ORM and often require executing raw SQL using `connection.execute(text('YOUR VERTICA SQL HERE'))`.
Fix: When using Vertica-specific SQL, wrap your statement in `sqlalchemy.text()` and execute it directly via the connection.

Install

pip install sqlalchemy-vertica Install `sqlalchemy-vertica`

Imports

create_engine
```
from sqlalchemy import create_engine
```
The `sqlalchemy-vertica` dialect auto-registers upon installation. You typically only need to import `create_engine` from SQLAlchemy itself and specify the dialect in your connection string.

Quickstart

This quickstart demonstrates how to establish a connection to a Vertica database using `sqlalchemy-vertica` and execute a simple SQL query. Ensure `VERTICA_USER`, `VERTICA_PASSWORD`, `VERTICA_HOST`, `VERTICA_PORT`, and `VERTICA_DATABASE` are correctly configured, preferably via environment variables for production systems.

import os
from sqlalchemy import create_engine, text

# Replace with your actual Vertica connection details
# It's recommended to use environment variables for sensitive info.
VERTICA_USER = os.environ.get("VERTICA_USER", "dbadmin")
VERTICA_PASSWORD = os.environ.get("VERTICA_PASSWORD", "password")
VERTICA_HOST = os.environ.get("VERTICA_HOST", "localhost")
VERTICA_PORT = os.environ.get("VERTICA_PORT", "5432")
VERTICA_DATABASE = os.environ.get("VERTICA_DATABASE", "VMART")

connection_string = (
    f"vertica+vertica_python://{VERTICA_USER}:{VERTICA_PASSWORD}"
    f"@{VERTICA_HOST}:{VERTICA_PORT}/{VERTICA_DATABASE}"
)

try:
    engine = create_engine(connection_string)
    with engine.connect() as connection:
        # Example: Execute a simple query
        result = connection.execute(text("SELECT 1 as test_col"))
        print(f"Connection successful! Result: {result.scalar()}")
except Exception as e:
    print(f"Failed to connect or execute query: {e}")

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