Add reader for PostgreSQL Databases

[kevinqz]

Hey all,

I have:

• Added a reader to connect and query PostgreSQL Databases.
• Included an example (.py file) of how to connect and query a database correctly.
• Updated the docs with the additional PostgreSQL option.

Best, Kevin Saltarelli

[jerryjliu]

thanks for doing this @kevinqz! any chance you could take a look at using the SQLDatabase class instead? https://gpt-index.readthedocs.io/en/latest/reference/struct_store.html - this is already used for our SQL index, and we could use it as a reader too (SQLAlchemy should allow for connecting to most structured databases including postgres)

[kevinqz]

Hi, @jerryjliu! Just added another commit in which I've:

• Added a DatabaseReader to connect to and query SQL Databases by using SQLAlchemy and the SQLDatabase class.
• Included an example (now with a Jupyter Notebook .ipynb file).
• Updated the docs with the additional DatabaseReader option.

Tried a few tests here and everything should be fine to go. Feel free to let me know if anything.

[kevinqz]

I see your point, @jerryjliu! I've made some changes:

• Made changes in the way to instantiate the DatabaseReader class. Inherited it as a BaseReader and added an instance variable called sql_database of the SQLDatabase class. Please let me know if I understood and implemented your points correctly.
• Also added the ability to start from an existing (SQLAlchemy) Engine - not sure if this is something excessive or necessary, please let me know your opinion.
• Removed 2 old files (related to PostgreSQL only).
• Added examples of how to instantiate the DatabaseReader class from sql_database (SQLDatabase), an engine (Engine), and an uri (string) in the DatabaseReaderDemo.ipynb file.

Feel free to let me know if I correctly addressed your points, ok? Still new to this whole area. :)

[jerryjliu]

I see your point, @jerryjliu! I've made some changes:

• Made changes in the way to instantiate the DatabaseReader class. Inherited it as a BaseReader and added an instance variable called sql_database of the SQLDatabase class. Please let me know if I understood and implemented your points correctly.
• Also added the ability to start from an existing (SQLAlchemy) Engine - not sure if this is something excessive or necessary, please let me know your opinion.
• Removed 2 old files (related to PostgreSQL only).
• Added examples of how to instantiate the DatabaseReader class from sql_database (SQLDatabase), an engine (Engine), and an uri (string) in the DatabaseReaderDemo.ipynb file.

Feel free to let me know if I correctly addressed your points, ok? Still new to this whole area. :)

nice, this is a lot better! could you remove the old files? there's TestDatabaseReader.ipynb, TestPostgresReader, and postgresql.py which can be removed

[kevinqz]

@jerryjliu, done! Let me know if I did it correctly this time. 😅