The COLUMNS_EXTENSIONS table (available as of MySQL 8.0.21) provides information about column attributes defined for primary and secondary storage engines.
The COLUMNS_EXTENSIONS table is reserved for future use.
The COLUMNS_EXTENSIONS table has these columns:
TABLE_CATALOG
The name of the catalog to which the table belongs. This value is always def.
TABLE_SCHEMA
The name of the schema (database) to which the table belongs.
TABLE_NAME
The name of the table.
COLUMN_NAME
The name of the column.
ENGINE_ATTRIBUTE
Column attributes defined for the primary storage engine. Reserved for future use.
SECONDARY_ENGINE_ATTRIBUTE
Column attributes defined for the secondary storage engine. Reserved for future use.