v.24.5Backward Incompatible Changes

Improved Query Performance and Access Control in system.columns

Queries from system.columns will work faster if there is a large number of columns, but many databases or tables are not granted for SHOW TABLES. Note that in previous versions, if you grant SHOW COLUMNS to individual columns without granting SHOW TABLES to the corresponding tables, the system.columns table will show these columns, but in a new version, it will skip the table entirely. Remove trace log messages "Access granted" and "Access denied" that slowed down queries. #63439 (Alexey Milovidov).