Japanese community user kindly reported this issue. The entry of blog was
posted in Japanese but you can find what's wrong by screenshots.

  http://d.hatena.ne.jp/shin/20090611/p1

When getPrecision() returns 0 (e.g. in PostgreSQL), validate() of
DBReadWriteHelper.java is not working properly. When we try to update
text on DB editor (invoked by show data), it causes the following dialog.

 http://shin.cside.com/diary/2009/0611-04.png

It seems that the following codes are not correct.

db.dataview/src/org/netbeans/modules/db/dataview/util/DBReadWriteHelper.java:

    public static Object validate(Object valueObj, DBColumn col) throws DBException {

                case Types.CHAR:
                case Types.VARCHAR:
                case Types.LONGVARCHAR:
                case -9:  //NVARCHAR
                case -8:  //ROWID
                case -15: //NCHAR
                    if (valueObj.toString().length() > col.getPrecision()) {
                        String colName = col.getQualifiedName(false);
                        String errMsg = "Too large data \'" + valueObj + "\' for column " + colName;
                        throw new DBException(errMsg);
                    }
                    return valueObj;

case col.getPrecision() == 0 should be cared for some databases. So
"col.getPrecision() != 0 &&" needs to be added.

                    if (col.getPrecision() != 0 && valueObj.toString().length() > col.getPrecision()) {