/**
* 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 static List<RelCollation> deduceMonotonicity(Prepare.PreparingTable table) {
final List<RelCollation> collationList = new ArrayList<RelCollation>();
// Deduce which fields the table is sorted on.
int i = -1;
for (RelDataTypeField field : table.getRowType().getFieldList()) {
++i;
final SqlMonotonicity monotonicity = table.getMonotonicity(field.getName());
if (monotonicity != SqlMonotonicity.NotMonotonic) {
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;
}
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;
}
/**
* Trims a child relational expression, then adds back a dummy project to restore the fields that
* were removed.
*
* <p>Sounds pointless? It causes unused fields to be removed further down the tree (towards the
* leaves), but it ensure that the consuming relational expression continues to see the same
* fields.
*
* @param rel Relational expression
* @param input Input relational expression, whose fields to trim
* @param fieldsUsed Bitmap of fields needed by the consumer
* @return New relational expression and its field mapping
*/
protected TrimResult trimChildRestore(
RelNode rel, RelNode input, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
TrimResult trimResult = trimChild(rel, input, fieldsUsed, extraFields);
if (trimResult.right.isIdentity()) {
return trimResult;
}
final RelDataType rowType = input.getRowType();
List<RelDataTypeField> fieldList = rowType.getFieldList();
final List<RexNode> exprList = new ArrayList<RexNode>();
final List<String> nameList = rowType.getFieldNames();
RexBuilder rexBuilder = rel.getCluster().getRexBuilder();
assert trimResult.right.getSourceCount() == fieldList.size();
for (int i = 0; i < fieldList.size(); i++) {
int source = trimResult.right.getTargetOpt(i);
RelDataTypeField field = fieldList.get(i);
exprList.add(
source < 0
? rexBuilder.makeZeroLiteral(field.getType())
: rexBuilder.makeInputRef(field.getType(), source));
}
RelNode project = CalcRel.createProject(trimResult.left, exprList, nameList);
return new TrimResult(project, Mappings.createIdentity(fieldList.size()));
}