Added PostgreSQL Support with Table Engine, Dictionary Source, and Database Engine

Why it matters

This feature enables seamless access to PostgreSQL data directly from ClickHouse without complex ETL processes. It solves the problem of integrating and querying data stored in PostgreSQL databases by providing native engines and sources that allow users to query and insert data with full support for multidimensional arrays. This enhances interoperability and simplifies workflows when combining analytical workloads across both database systems.

How to use it

To use this feature, users can create a table using the PostgreSQL table engine or utilize the PostgreSQL table function in SELECT queries to directly interact with PostgreSQL tables. Additionally, users can define a dictionary with the PostgreSQL dictionary source or create a database using the PostgreSQL database engine. Configuration requires specifying connection parameters such as host, port, database name, user, and password.