SET @start_global_value = @@global.ROCKSDB_MANIFEST_PREALLOCATION_SIZE;
SELECT @start_global_value;
@start_global_value
4194304
"Trying to set variable @@global.ROCKSDB_MANIFEST_PREALLOCATION_SIZE to 444. It should fail because it is readonly."
SET @@global.ROCKSDB_MANIFEST_PREALLOCATION_SIZE   = 444;
ERROR HY000: Variable 'rocksdb_manifest_preallocation_size' is a read only variable
