Why does MySQL's boolean type map to a tinyint instead of an enum?

Question

Were there performance or compatibility reasons for going with tinyint(1) over an enum? Something else?

Answer 1

It may interest you to know that MySQL indexes ENUMs with integers.

The SQL standard has included a boolean data type since 1999 - with valid values being true, false, unknown, or null. Implementation across various database systems is spotty.

MySQL does not support a true boolean data type - BOOLEAN maps to TINYINT, which takes up only 1 byte. MySQL interprets 0 as false, all other numbers are true.