v.20.12Improvement

Throw Error for Non-Existing Column Replacement in Column Transformer

Throw error when use column transformer replaces non existing column. #16183 (hexiaoting).
ClickHouse now throws an error when a column transformer attempts to replace a non-existing column.

Why it matters

This feature improves error handling by preventing silent failures or unexpected behavior that occur when a column transformer tries to replace a column that does not exist in the table schema. It helps users quickly identify and fix issues related to incorrect column references during transformation.

How to use it

When using column transformers, ensure that the columns specified for replacement exist in the table schema. If a specified column does not exist, ClickHouse will throw an error, guiding you to correct the column names or transformation logic.