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10 months ago 🤖
Hello @elghali! :wave:
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It seems like you're encountering an issue with the SQLDatabase.from_uri method when trying to connect to a Vertica database. This is likely due to the fact that Vertica does not have a 'pg_catalog' schema, which is a system schema found in PostgreSQL.
The SQLDatabase.from_uri method in LangChain uses SQLAlchemy's create_engine function to create a database engine from a URI. SQLAlchemy supports a wide range of SQL databases, including Vertica. Therefore, as long as the correct Vertica database URI is provided, the from_uri method should be able to create a connection to a Vertica database.
Here is the relevant code:
@classmethod
def from_uri(
cls, database_uri: str, engine_args: Optional[dict] = None, **kwargs: Any
) -> SQLDatabase:
"""Construct a SQLAlchemy engine from URI."""
_engine_args = engine_args or {}
return cls(create_engine(database_uri, **_engine_args), **kwargs)In this method, database_uri is the URI of the database you want to connect to. For Vertica, it should be in the format: vertica+pyodbc://<user>:<password>@<dsn>. The engine_args parameter is an optional dictionary of arguments to be passed to SQLAlchemy's create_engine function. The **kwargs parameter is used to pass any additional arguments to the SQLDatabase constructor.
To avoid the error, you need to specify the correct schema that exists in your Vertica database when creating the SQLDatabase object. Here is an example of how you can do this:
from sqlalchemy import create_engine
from libs.community.langchain_community.utilities.sql_database import SQLDatabase
# Create a SQLAlchemy engine for Vertica
engine = create_engine('vertica+pyodbc://<username>:<password>@<dsn_name>')
# Create an SQLDatabase object
db = SQLDatabase(engine, schema='<your_vertica_schema>')In this example, replace <username>, <password>, <dsn_name>, and <your_vertica_schema> with your actual Vertica username, password, DSN name, and schema respectively.
Please note that you need to have the vertica-python or pyodbc package installed and a valid ODBC connection set up for Vertica. The connection string format may vary depending on your specific setup.
I hope this helps! If you have any other questions or need further clarification, feel free to ask.
Sources:
- libs/community/langchain_community/utilities/sql_database.py
- libs/langchain/langchain/utilities/sql_database.py
Sources
- libs/community/langchain_community/utilities/sql_database.py
- libs/langchain/langchain/utilities/sql_database.py
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liv4unix
elghali
Checked other resources
Example Code
Description
When I use the above snippet to create an SQLDatabase object for vertica, I get the below error:
Which makes sense because Vertica does not have pg_catalog schema, but how can I create the object without the reflect part where it tries to read from pg_catalog
System Info
sqlalchemy-vertica-python~=0.6.3 langchain==0.1.0
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