In MySQL, all float values are using the FLOAT type which results (without an additional precision value which is never used in ezp) in a 4 bytes floating point number.
In PostgreSQL, all float values are stored using "double precision" which corresponds to MySQL's DOUBLE [PRECISION]. Those are 8 bytes floating point numbers.
The correct equivalent for FLOAT is "real" in PostgreSQL.
The "db upgrade check" feature also contains those confusions.