MySQL 8.0: Support for BLOBs in TempTable engine
In some cases, the server creates internal temporary tables while processing statements. These tables could be stored in memory or on disk – the first option is preferred but there exist some limitations. One of such restrictions was presence of TEXT or BLOB columns in the table; as in-memory storage engines (MEMORY and TempTable) did not supported these types server had to use the on-disk engine (InnoDB or MyISAM).…
Source: MySQL 8.0: Support for BLOBs in TempTable engine
