v.23.10Improvement

SHOW COLUMNS Enhancements for FixedString and MySQL Type Mapping

Official CH changelog text
SHOW COLUMNS now correctly reports type FixedString as BLOB if setting use_mysql_types_in_show_columns is on. Also added two new settings, mysql_map_string_to_text_in_show_columns and mysql_map_fixed_string_to_text_in_show_columns to switch the output for types String and FixedString as TEXT or BLOB. #55617 (Serge Klochkov).
SHOW COLUMNS now accurately maps the FixedString type to BLOB when the use_mysql_types_in_show_columns setting is enabled. Additionally, two new settings allow customizing the output for String and FixedString types between TEXT and BLOB types.

Why it matters

This feature improves compatibility and clarity when using SHOW COLUMNS by aligning the output types with MySQL conventions. It addresses the inconsistency in type representation, giving users the flexibility to switch String and FixedString outputs to either TEXT or BLOB, which can simplify integration with applications expecting MySQL-like type mappings.

How to use it

Enable the feature by setting use_mysql_types_in_show_columns to 1. Then optionally configure mysql_map_string_to_text_in_show_columns and mysql_map_fixed_string_to_text_in_show_columns to 1 or 0 to control whether String and FixedString types are shown as TEXT or BLOB respectively. Example:

SET use_mysql_types_in_show_columns = 1;
SET mysql_map_string_to_text_in_show_columns = 1;
SET mysql_map_fixed_string_to_text_in_show_columns = 0;
SHOW COLUMNS FROM your_table;

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