v.18.14Improvement

Improvements in WHERE Clause Handling for MySQL and ODBC Queries

Comparisons with constant expressions in a WHERE clause are passed to the remote server when querying from MySQL and ODBC tables. Previously, only comparisons with constants were passed. #3182
Improve query pushdown by passing comparisons with constant expressions in the WHERE clause to remote servers for MySQL and ODBC tables.

Why it matters

This feature enhances query performance and efficiency by allowing the ClickHouse server to delegate more complex constant expression comparisons in WHERE clauses directly to the remote data source (MySQL or ODBC). Previously, only simple comparisons with constant values were pushed down, limiting optimization opportunities.

How to use it

No special configuration is required. When querying MySQL or ODBC tables, ClickHouse will automatically push down comparisons involving constant expressions in the WHERE clause to the remote server to optimize query execution.