public List<Type> guessTypes() throws SQLException {
final ResultSetMetaData metaData = resultSet.getMetaData();
final int columnCount = metaData.getColumnCount();
assert this.types == null || this.types.size() == columnCount;
List<Type> types = new ArrayList<Type>();
for (int i = 0; i < columnCount; i++) {
final Type suggestedType = this.types == null ? null : this.types.get(i);
types.add(guessType(suggestedType, metaData, i));
}
return types;
}
/**
* Chooses the most appropriate type for accessing the values of a column in a result set.
*
* <p>NOTE: It is possible that this method is driver-dependent. If this is the case, move it to
* {@link mondrian.spi.Dialect}.
*
* @param suggestedType Type suggested by Level.internalType attribute
* @param metaData Result set metadata
* @param i Column ordinal (0-based)
* @return Best client type
* @throws SQLException on error
*/
public static Type guessType(Type suggestedType, ResultSetMetaData metaData, int i)
throws SQLException {
if (suggestedType != null) {
return suggestedType;
}
final String typeName = metaData.getColumnTypeName(i + 1);
final int columnType = metaData.getColumnType(i + 1);
int precision;
int scale;
switch (columnType) {
case Types.SMALLINT:
case Types.INTEGER:
case Types.BOOLEAN:
return Type.INT;
case Types.NUMERIC:
precision = metaData.getPrecision(i + 1);
scale = metaData.getScale(i + 1);
if (precision == 0
&& (scale == 0 || scale == -127)
&& (typeName.equalsIgnoreCase("NUMBER") || (typeName.equalsIgnoreCase("NUMERIC")))) {
// In Oracle and Greenplum the NUMBER/NUMERIC datatype with no
// precision or scale (not NUMBER(p) or NUMBER(p, s)) means
// floating point. Some drivers represent this with scale 0,
// others scale -127.
//
// There is a further problem. In GROUPING SETS queries, Oracle
// loosens the type of columns compared to mere GROUP BY
// queries. We need integer GROUP BY columns to remain integers,
// otherwise the segments won't be found; but if we convert
// measure (whose column names are like "m0", "m1") to integers,
// data loss will occur.
final String columnName = metaData.getColumnName(i + 1);
if (columnName.startsWith("m")) {
return Type.OBJECT;
} else {
return Type.INT;
}
}
return getDecimalType(precision, scale);
case Types.DECIMAL:
precision = metaData.getPrecision(i + 1);
scale = metaData.getScale(i + 1);
return getDecimalType(precision, scale);
case Types.DOUBLE:
case Types.FLOAT:
return Type.DOUBLE;
default:
return Type.OBJECT;
}
}
