Add Schema Inference to PostgreSQL, MySQL, MeiliSearch, and SQLite Table Engines

Why it matters

This feature addresses the problem of manually defining table schemas when connecting ClickHouse to external data sources such as PostgreSQL, MySQL, MeiliSearch, and SQLite. By automatically inferring the schema, it simplifies integration, reduces configuration errors, and accelerates the process of setting up external tables.

How to use it

When creating a table with one of the supported external table engines (PostgreSQL, MySQL, MeiliSearch, or SQLite), users can enable schema inference by omitting explicit column definitions. ClickHouse will automatically retrieve and apply the schema from the external data source.