Add Redis Table Engine and Function for External Queries

Why it matters

This feature solves the problem of integrating Redis data seamlessly into ClickHouse queries, allowing users to combine and analyze Redis-stored data without requiring separate data pipelines or ETL processes.

How to use it

Users can create a table using the Redis table engine by specifying connection parameters to the Redis server. Alternatively, they can use the redis table function in their queries to access Redis data dynamically. For example:

CREATE TABLE redis_table ENGINE = Redis('redis_host:6379', 'key_pattern', 'hash');

SELECT * FROM redis('redis_host:6379', 'key_pattern', 'hash');