A query projects a longtext column and retrieves the precision from the ResultsetMetata.
A value of -1 is returned where 0 was expected.
https://docs.oracle.com/javase/8/docs/api/java/sql/ResultSetMetaData.html#getPrecision-int-
create table TCLOB ( RNUM integer not null , CCLOB longtext null ,
constraint CLOBPK primary key( RNUM ) , SHARD KEY ( RNUM ) ) ;