Increasing the tmp_table size in Aurora MySQL

Hello,

This should be the issue at RDS side. In MySQL v8.0, there is a new storage engine named 'TempTable' that enabled with a new variable called "internal_tmp_mem_storage_engine" in parameter group.

This TempTable engine will occupy disk space by creating memory mapped temp files when the max amount of memory has been used, which can be defined using "temptable_max_ram" variable. The problem with these memory mapped files are created in /tmp directory. Once the partition is full, the query fails with "The table 'xxxxx' is full" error.

Please check if you have internal_tmp_mem_storage_engine parameter group is set to TempTable in the RDS instance. If yes, you can modify the parameter group internal_tmp_mem_storage_engine to 'MEMORY'

When storage engine is using MEMORY, then the maximum size for in-memory temporary table is defined by the tmp_table_size or max_heap_table_size" which can be increased as you mentioned. In that case, when the in-memory temporary table exceeds the limit, MySQL automatically converts the data to on-disk temporary table.