/**
* Derives the list of column names suitable for NATURAL JOIN. These are the columns that occur
* exactly once on each side of the join.
*
* @param leftRowType Row type of left input to the join
* @param rightRowType Row type of right input to the join
* @return List of columns that occur once on each side
*/
public static List<String> deriveNaturalJoinColumnList(
RelDataType leftRowType, RelDataType rightRowType) {
List<String> naturalColumnNames = new ArrayList<String>();
final List<String> leftNames = leftRowType.getFieldNames();
final List<String> rightNames = rightRowType.getFieldNames();
for (String name : leftNames) {
if ((Collections.frequency(leftNames, name) == 1)
&& (Collections.frequency(rightNames, name) == 1)) {
naturalColumnNames.add(name);
}
}
return naturalColumnNames;
}
private List<AggregateCall> transformAggCalls(
RelDataTypeFactory typeFactory, int nGroupCols, List<AggregateCall> origCalls) {
List<AggregateCall> newCalls = new ArrayList<AggregateCall>();
int iInput = nGroupCols;
for (AggregateCall origCall : origCalls) {
if (origCall.isDistinct()
|| !SUPPORTED_AGGREGATES.containsKey(origCall.getAggregation().getClass())) {
return null;
}
Aggregation aggFun;
RelDataType aggType;
if (origCall.getAggregation().getName().equals("COUNT")) {
aggFun = new SqlSumEmptyIsZeroAggFunction(origCall.getType());
SqlAggFunction af = (SqlAggFunction) aggFun;
final AggregateRelBase.AggCallBinding binding =
new AggregateRelBase.AggCallBinding(
typeFactory, af, Collections.singletonList(origCall.getType()), nGroupCols);
// count(any) is always not null, however nullability of sum might
// depend on the number of columns in GROUP BY.
// Here we use SUM0 since we are sure we will not face nullable
// inputs nor we'll face empty set.
aggType = af.inferReturnType(binding);
} else {
aggFun = origCall.getAggregation();
aggType = origCall.getType();
}
AggregateCall newCall =
new AggregateCall(
aggFun,
origCall.isDistinct(),
Collections.singletonList(iInput),
aggType,
origCall.getName());
newCalls.add(newCall);
++iInput;
}
return newCalls;
}
public static void getSchemaObjectMonikers(
SqlValidatorCatalogReader catalogReader, List<String> names, List<SqlMoniker> hints) {
// Assume that the last name is 'dummy' or similar.
List<String> subNames = Util.skipLast(names);
hints.addAll(catalogReader.getAllSchemaObjectNames(subNames));
// If the name has length 0, try prepending the name of the default
// schema. So, the empty name would yield a list of tables in the
// default schema, as well as a list of schemas from the above code.
if (subNames.size() == 0) {
hints.addAll(
catalogReader.getAllSchemaObjectNames(
Collections.singletonList(catalogReader.getSchemaName())));
}
}
public void onMatch(RelOptRuleCall call) {
ProjectRel project = (ProjectRel) call.rels[0];
List<RexNode> expList = new ArrayList<RexNode>(Arrays.asList(project.getChildExps()));
if (reduceExpressions(project, expList)) {
call.transformTo(
new ProjectRel(
project.getCluster(),
project.getChild(),
expList.toArray(new RexNode[expList.size()]),
project.getRowType(),
ProjectRel.Flags.Boxed,
Collections.<RelCollation>emptyList()));
// New plan is absolutely better than old plan.
call.getPlanner().setImportance(project, 0.0);
}
}
