@Override
public Expression visitProject(ProjectNode node, Void context) {
// TODO: add simple algebraic solver for projection translation (right now only considers
// identity projections)
Expression underlyingPredicate = node.getSource().accept(this, context);
Iterable<Expression> projectionEqualities =
transform(
filter(node.getOutputMap().entrySet(), not(symbolMatchesExpression())),
new Function<Map.Entry<Symbol, Expression>, Expression>() {
@Override
public Expression apply(Map.Entry<Symbol, Expression> entry) {
QualifiedNameReference reference =
new QualifiedNameReference(entry.getKey().toQualifiedName());
Expression expression = entry.getValue();
return new ComparisonExpression(
ComparisonExpression.Type.EQUAL, reference, expression);
}
});
return pullExpressionThroughSymbols(
combineConjuncts(
ImmutableList.<Expression>builder()
.addAll(projectionEqualities)
.add(underlyingPredicate)
.build()),
node.getOutputSymbols());
}
@Override
public PlanNode visitProject(ProjectNode node, RewriteContext<Set<Symbol>> context) {
ImmutableSet.Builder<Symbol> expectedInputs = ImmutableSet.builder();
ImmutableMap.Builder<Symbol, Expression> builder = ImmutableMap.builder();
for (int i = 0; i < node.getOutputSymbols().size(); i++) {
Symbol output = node.getOutputSymbols().get(i);
Expression expression = node.getAssignments().get(output);
if (context.get().contains(output)) {
expectedInputs.addAll(DependencyExtractor.extractUnique(expression));
builder.put(output, expression);
}
}
PlanNode source = context.rewrite(node.getSource(), expectedInputs.build());
return new ProjectNode(node.getId(), source, builder.build());
}
@Override
public PlanNode visitProject(ProjectNode node, RewriteContext<Void> context) {
PlanNode source = context.rewrite(node.getSource());
if (!node.getOutputSymbols().equals(source.getOutputSymbols())) {
// Can't get rid of this projection. It constrains the output tuple from the underlying
// operator
return replaceChildren(node, ImmutableList.of(source));
}
if (node.isIdentity()) {
return source;
}
return replaceChildren(node, ImmutableList.of(source));
}
private RelationPlan addConstantSampleWeight(RelationPlan subPlan) {
ImmutableMap.Builder<Symbol, Expression> projections = ImmutableMap.builder();
for (Symbol symbol : subPlan.getOutputSymbols()) {
Expression expression = new QualifiedNameReference(symbol.toQualifiedName());
projections.put(symbol, expression);
}
Expression one = new LongLiteral("1");
Symbol sampleWeightSymbol = symbolAllocator.newSymbol("$sampleWeight", BIGINT);
projections.put(sampleWeightSymbol, one);
ProjectNode projectNode =
new ProjectNode(idAllocator.getNextId(), subPlan.getRoot(), projections.build());
return new RelationPlan(
projectNode,
subPlan.getDescriptor(),
projectNode.getOutputSymbols(),
Optional.of(sampleWeightSymbol));
}
