@Override
public PlanNode rewriteAggregation(
AggregationNode node,
Expression inheritedPredicate,
PlanRewriter<Expression> planRewriter) {
EqualityInference equalityInference = createEqualityInference(inheritedPredicate);
List<Expression> pushdownConjuncts = new ArrayList<>();
List<Expression> postAggregationConjuncts = new ArrayList<>();
// Strip out non-deterministic conjuncts
postAggregationConjuncts.addAll(
ImmutableList.copyOf(filter(extractConjuncts(inheritedPredicate), not(deterministic()))));
inheritedPredicate = stripNonDeterministicConjuncts(inheritedPredicate);
// Sort non-equality predicates by those that can be pushed down and those that cannot
for (Expression conjunct : EqualityInference.nonInferrableConjuncts(inheritedPredicate)) {
Expression rewrittenConjunct =
equalityInference.rewriteExpression(conjunct, in(node.getGroupBy()));
if (rewrittenConjunct != null) {
pushdownConjuncts.add(rewrittenConjunct);
} else {
postAggregationConjuncts.add(conjunct);
}
}
// Add the equality predicates back in
EqualityInference.EqualityPartition equalityPartition =
equalityInference.generateEqualitiesPartitionedBy(in(node.getGroupBy()));
pushdownConjuncts.addAll(equalityPartition.getScopeEqualities());
postAggregationConjuncts.addAll(equalityPartition.getScopeComplementEqualities());
postAggregationConjuncts.addAll(equalityPartition.getScopeStraddlingEqualities());
PlanNode rewrittenSource =
planRewriter.rewrite(node.getSource(), combineConjuncts(pushdownConjuncts));
PlanNode output = node;
if (rewrittenSource != node.getSource()) {
output =
new AggregationNode(
node.getId(),
rewrittenSource,
node.getGroupBy(),
node.getAggregations(),
node.getFunctions(),
node.getMasks(),
node.getStep(),
node.getSampleWeight(),
node.getConfidence());
}
if (!postAggregationConjuncts.isEmpty()) {
output =
new FilterNode(
idAllocator.getNextId(), output, combineConjuncts(postAggregationConjuncts));
}
return output;
}
@Override
public PlanNode rewriteSemiJoin(
SemiJoinNode node, Expression inheritedPredicate, PlanRewriter<Expression> planRewriter) {
Expression sourceEffectivePredicate = EffectivePredicateExtractor.extract(node.getSource());
List<Expression> sourceConjuncts = new ArrayList<>();
List<Expression> filteringSourceConjuncts = new ArrayList<>();
List<Expression> postJoinConjuncts = new ArrayList<>();
// TODO: see if there are predicates that can be inferred from the semi join output
// Push inherited and source predicates to filtering source via a contrived join predicate
// (but needs to avoid touching NULL values in the filtering source)
Expression joinPredicate =
equalsExpression(node.getSourceJoinSymbol(), node.getFilteringSourceJoinSymbol());
EqualityInference joinInference =
createEqualityInference(inheritedPredicate, sourceEffectivePredicate, joinPredicate);
for (Expression conjunct :
Iterables.concat(
EqualityInference.nonInferrableConjuncts(inheritedPredicate),
EqualityInference.nonInferrableConjuncts(sourceEffectivePredicate))) {
Expression rewrittenConjunct =
joinInference.rewriteExpression(conjunct, equalTo(node.getFilteringSourceJoinSymbol()));
if (rewrittenConjunct != null && DeterminismEvaluator.isDeterministic(rewrittenConjunct)) {
// Alter conjunct to include an OR filteringSourceJoinSymbol IS NULL disjunct
Expression rewrittenConjunctOrNull =
expressionOrNullSymbols(equalTo(node.getFilteringSourceJoinSymbol()))
.apply(rewrittenConjunct);
filteringSourceConjuncts.add(rewrittenConjunctOrNull);
}
}
EqualityInference.EqualityPartition joinInferenceEqualityPartition =
joinInference.generateEqualitiesPartitionedBy(
equalTo(node.getFilteringSourceJoinSymbol()));
filteringSourceConjuncts.addAll(
ImmutableList.copyOf(
transform(
joinInferenceEqualityPartition.getScopeEqualities(),
expressionOrNullSymbols(equalTo(node.getFilteringSourceJoinSymbol())))));
// Push inheritedPredicates down to the source if they don't involve the semi join output
EqualityInference inheritedInference = createEqualityInference(inheritedPredicate);
for (Expression conjunct : EqualityInference.nonInferrableConjuncts(inheritedPredicate)) {
Expression rewrittenConjunct =
inheritedInference.rewriteExpression(conjunct, in(node.getSource().getOutputSymbols()));
// Since each source row is reflected exactly once in the output, ok to push
// non-deterministic predicates down
if (rewrittenConjunct != null) {
sourceConjuncts.add(rewrittenConjunct);
} else {
postJoinConjuncts.add(conjunct);
}
}
// Add the inherited equality predicates back in
EqualityInference.EqualityPartition equalityPartition =
inheritedInference.generateEqualitiesPartitionedBy(
in(node.getSource().getOutputSymbols()));
sourceConjuncts.addAll(equalityPartition.getScopeEqualities());
postJoinConjuncts.addAll(equalityPartition.getScopeComplementEqualities());
postJoinConjuncts.addAll(equalityPartition.getScopeStraddlingEqualities());
PlanNode rewrittenSource =
planRewriter.rewrite(node.getSource(), combineConjuncts(sourceConjuncts));
PlanNode rewrittenFilteringSource =
planRewriter.rewrite(
node.getFilteringSource(), combineConjuncts(filteringSourceConjuncts));
PlanNode output = node;
if (rewrittenSource != node.getSource()
|| rewrittenFilteringSource != node.getFilteringSource()) {
output =
new SemiJoinNode(
node.getId(),
rewrittenSource,
rewrittenFilteringSource,
node.getSourceJoinSymbol(),
node.getFilteringSourceJoinSymbol(),
node.getSemiJoinOutput());
}
if (!postJoinConjuncts.isEmpty()) {
output =
new FilterNode(idAllocator.getNextId(), output, combineConjuncts(postJoinConjuncts));
}
return output;
}
private OuterJoinPushDownResult processOuterJoin(
Expression inheritedPredicate,
Expression outerEffectivePredicate,
Expression innerEffectivePredicate,
Expression joinPredicate,
Collection<Symbol> outerSymbols) {
checkArgument(
Iterables.all(
DependencyExtractor.extractUnique(outerEffectivePredicate), in(outerSymbols)),
"outerEffectivePredicate must only contain symbols from outerSymbols");
checkArgument(
Iterables.all(
DependencyExtractor.extractUnique(innerEffectivePredicate), not(in(outerSymbols))),
"innerEffectivePredicate must not contain symbols from outerSymbols");
ImmutableList.Builder<Expression> outerPushdownConjuncts = ImmutableList.builder();
ImmutableList.Builder<Expression> innerPushdownConjuncts = ImmutableList.builder();
ImmutableList.Builder<Expression> postJoinConjuncts = ImmutableList.builder();
// Strip out non-deterministic conjuncts
postJoinConjuncts.addAll(filter(extractConjuncts(inheritedPredicate), not(deterministic())));
inheritedPredicate = stripNonDeterministicConjuncts(inheritedPredicate);
outerEffectivePredicate = stripNonDeterministicConjuncts(outerEffectivePredicate);
innerEffectivePredicate = stripNonDeterministicConjuncts(innerEffectivePredicate);
joinPredicate = stripNonDeterministicConjuncts(joinPredicate);
// Generate equality inferences
EqualityInference inheritedInference = createEqualityInference(inheritedPredicate);
EqualityInference outerInference =
createEqualityInference(inheritedPredicate, outerEffectivePredicate);
EqualityInference.EqualityPartition equalityPartition =
inheritedInference.generateEqualitiesPartitionedBy(in(outerSymbols));
Expression outerOnlyInheritedEqualities =
combineConjuncts(equalityPartition.getScopeEqualities());
EqualityInference potentialNullSymbolInference =
createEqualityInference(
outerOnlyInheritedEqualities,
outerEffectivePredicate,
innerEffectivePredicate,
joinPredicate);
EqualityInference potentialNullSymbolInferenceWithoutInnerInferred =
createEqualityInference(
outerOnlyInheritedEqualities, outerEffectivePredicate, joinPredicate);
// Sort through conjuncts in inheritedPredicate that were not used for inference
for (Expression conjunct : EqualityInference.nonInferrableConjuncts(inheritedPredicate)) {
Expression outerRewritten = outerInference.rewriteExpression(conjunct, in(outerSymbols));
if (outerRewritten != null) {
outerPushdownConjuncts.add(outerRewritten);
// A conjunct can only be pushed down into an inner side if it can be rewritten in terms
// of the outer side
Expression innerRewritten =
potentialNullSymbolInference.rewriteExpression(outerRewritten, not(in(outerSymbols)));
if (innerRewritten != null) {
innerPushdownConjuncts.add(innerRewritten);
}
} else {
postJoinConjuncts.add(conjunct);
}
}
// See if we can push down any outer or join predicates to the inner side
for (Expression conjunct :
EqualityInference.nonInferrableConjuncts(and(outerEffectivePredicate, joinPredicate))) {
Expression rewritten =
potentialNullSymbolInference.rewriteExpression(conjunct, not(in(outerSymbols)));
if (rewritten != null) {
innerPushdownConjuncts.add(rewritten);
}
}
// TODO: consider adding join predicate optimizations to outer joins
// Add the equalities from the inferences back in
outerPushdownConjuncts.addAll(equalityPartition.getScopeEqualities());
postJoinConjuncts.addAll(equalityPartition.getScopeComplementEqualities());
postJoinConjuncts.addAll(equalityPartition.getScopeStraddlingEqualities());
innerPushdownConjuncts.addAll(
potentialNullSymbolInferenceWithoutInnerInferred
.generateEqualitiesPartitionedBy(not(in(outerSymbols)))
.getScopeEqualities());
return new OuterJoinPushDownResult(
combineConjuncts(outerPushdownConjuncts.build()),
combineConjuncts(innerPushdownConjuncts.build()),
combineConjuncts(postJoinConjuncts.build()));
}