@Override
public void visit(Column column) {
// extract type for the column
String tableSchemaName = _tan.getSchemaName(ParserUtil.getComponentName(column.getTable()));
String columnName = column.getColumnName();
TypeConversion tc = _schema.getType(tableSchemaName, columnName);
// extract the position (index) of the required column
int position =
HierarchyExtractor.extractComponentIndex(
column, _affectedComponent, _queryPlan, _schema, _tan);
ValueExpression ve = new ColumnReference(tc, position);
_exprStack.push(ve);
}
private int attachToQueryPlan() {
if (_aggOps.isEmpty()) {
ProjectionOperator project = new ProjectionOperator(_selectExpr);
_affectedComponent.setProjection(project);
return NON_AGG;
} else if (_aggOps.size() == 1) {
// all the others are group by
AggregateOperator firstAgg = _aggOps.get(0);
if (ParserUtil.isAllColumnRefs(_selectExpr)) {
// plain fields in select
List<Integer> groupByColumns = ParserUtil.extractColumnIndexes(_selectExpr);
firstAgg.setGroupByColumns(groupByColumns);
// Setting new level of components is necessary for correctness only for distinct in
// aggregates
// but it's certainly pleasant to have the final result grouped on nodes by group by
// columns.
boolean newLevel = !(HierarchyExtractor.isHashedBy(_affectedComponent, groupByColumns));
if (newLevel) {
_affectedComponent.setHashIndexes(groupByColumns);
OperatorComponent newComponent =
new OperatorComponent(
_affectedComponent, ParserUtil.generateUniqueName("OPERATOR"), _queryPlan)
.setAggregation(firstAgg);
// this now becomes "active component"
_affectedComponent = newComponent;
} else {
_affectedComponent.setAggregation(firstAgg);
}
} else {
// Sometimes selectExpr contains other functions, so we have to use projections instead of
// simple groupBy
// Check for complexity
if (_affectedComponent.getHashExpressions() != null
&& !_affectedComponent.getHashExpressions().isEmpty()) {
throw new RuntimeException(
"Too complex: cannot have hashExpression both for joinCondition and groupBy!");
}
// WARNING: _selectExpr cannot be used on two places: that's why we do deep copy
_affectedComponent.setHashExpressions((List<ValueExpression>) DeepCopy.copy(_selectExpr));
// always new level
ProjectionOperator groupByProj =
new ProjectionOperator((List<ValueExpression>) DeepCopy.copy(_selectExpr));
firstAgg.setGroupByProjection(groupByProj);
OperatorComponent newComponent =
new OperatorComponent(
_affectedComponent, ParserUtil.generateUniqueName("OPERATOR"), _queryPlan)
.setAggregation(firstAgg);
// this now becomes "active component"
_affectedComponent = newComponent;
}
return AGG;
} else {
throw new RuntimeException("For now only one aggregate function supported!");
}
}