/**
* Looks up a field with a given name, returning null if not found.
*
* @param rowType Row type
* @param columnName Field name
* @return Field, or null if not found
*/
public static RelDataTypeField lookupField(
boolean caseSensitive, final RelDataType rowType, String columnName) {
RelDataTypeField field = rowType.getField(columnName, caseSensitive);
if (field != null) {
return field;
}
// If record type is flagged as having "any field you ask for",
// return a type. (TODO: Better way to mark accommodating types.)
RelDataTypeField extra = RelDataTypeImpl.extra(rowType);
if (extra != null) {
return new RelDataTypeFieldImpl(columnName, -1, extra.getType());
}
return null;
}
public static RelDataType createTypeFromProjection(
RelDataType type,
List<String> columnNameList,
RelDataTypeFactory typeFactory,
boolean caseSensitive) {
// If the names in columnNameList and type have case-sensitive differences,
// the resulting type will use those from type. These are presumably more
// canonical.
final List<RelDataTypeField> fields = new ArrayList<RelDataTypeField>(columnNameList.size());
for (String name : columnNameList) {
RelDataTypeField field = type.getField(name, caseSensitive);
fields.add(type.getFieldList().get(field.getIndex()));
}
return typeFactory.createStructType(fields);
}
/**
* Generates a cast for a row type.
*
* @param rexBuilder RexBuilder to use for constructing casts
* @param lhsRowType target row type
* @param rhsExps expressions to be cast
* @return cast expressions
*/
public static RexNode[] generateCastExpressions(
RexBuilder rexBuilder, RelDataType lhsRowType, RexNode[] rhsExps) {
RelDataTypeField[] lhsFields = lhsRowType.getFields();
final int fieldCount = lhsFields.length;
RexNode[] castExps = new RexNode[fieldCount];
assert fieldCount == rhsExps.length;
for (int i = 0; i < fieldCount; ++i) {
RelDataTypeField lhsField = lhsFields[i];
RelDataType lhsType = lhsField.getType();
RelDataType rhsType = rhsExps[i].getType();
if (lhsType.equals(rhsType)) {
castExps[i] = rhsExps[i];
} else {
castExps[i] = rexBuilder.makeCast(lhsType, rhsExps[i]);
}
}
return castExps;
}
private List<RelCollation> deduceMonotonicity(SqlValidatorTable table) {
final RelDataType rowType = table.getRowType();
final List<RelCollation> collationList = new ArrayList<RelCollation>();
// Deduce which fields the table is sorted on.
int i = -1;
for (RelDataTypeField field : rowType.getFieldList()) {
++i;
final SqlMonotonicity monotonicity = table.getMonotonicity(field.getName());
if (monotonicity != SqlMonotonicity.NOT_MONOTONIC) {
final RelFieldCollation.Direction direction =
monotonicity.isDecreasing()
? RelFieldCollation.Direction.DESCENDING
: RelFieldCollation.Direction.ASCENDING;
collationList.add(
RelCollationImpl.of(
new RelFieldCollation(
i, direction, RelFieldCollation.NullDirection.UNSPECIFIED)));
}
}
return collationList;
}