For Boolean purpose column which one is better: nullable
I know bool is an alias for tinyint(1) , but in "High Performance MySQL" book that published by O'reilly said:
"If you want to store a true/false value in a single bit of storage space, another option is to create a nullable CHAR(0) column. This column is capable of storing either the absence of a value (NULL) or a zero-length value (the empty string). "
which one is better for size, performance, indexing or ...
UPDATE: I found this link useful for this question: Efficient Boolean value storage for Innodb Tables