Derby 10.2.1.7 rejects a data type of "FLOAT(53)" despite the
documentation including:
"The default precision for FLOAT is 53 and is equivalent to DOUBLE
PRECISION"
The error given is
java.sql.SQLSyntaxErrorException: Value '53' is not a valid precision
for FLOAT
Although an 8 byte IEEE floating point value has 52 explicit mantissa
bits, there is also an implicit 1 bit, so 53 is the correct precision
(at least that is my understanding) for normal values.
http://issues.apache.org/jira/browse/DERBY-2287
suggests that someone thinks 52 is right answer.
Mark Thornton