julianhyde commented on a change in pull request #1078: [CALCITE-896] Remove
Aggregate if grouping columns are unique and all functions are splittable
URL: https://github.com/apache/calcite/pull/1078#discussion_r261428663
##########
File path:
core/src/main/java/org/apache/calcite/rel/rules/AggregateRemoveRule.java
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@@ -58,37 +68,63 @@ public AggregateRemoveRule(Class<? extends Aggregate>
aggregateClass,
// distinct to make it correct up-front, we can get rid of the reference
// to the child here.
super(
- operand(aggregateClass,
+ operandJ(aggregateClass, null, agg -> isAggregateSupported(agg),
operand(RelNode.class, any())),
relBuilderFactory, null);
}
+ private static boolean isAggregateSupported(Aggregate aggregate) {
+ if (aggregate.indicator ||
+ aggregate.getGroupType() != Aggregate.Group.SIMPLE) {
+ return false;
+ }
+ // If any aggregate functions do not support splitting, bail out
+ for (AggregateCall aggregateCall : aggregate.getAggCallList()) {
+ if (aggregateCall.filterArg >= 0 ||
+ aggregateCall.getAggregation()
+ .unwrap(SqlSplittableAggFunction.class) == null) {
+ return false;
+ }
+ }
+ return true;
+ }
+
//~ Methods ----------------------------------------------------------------
public void onMatch(RelOptRuleCall call) {
final Aggregate aggregate = call.rel(0);
final RelNode input = call.rel(1);
- if (!aggregate.getAggCallList().isEmpty() || aggregate.indicator) {
- return;
- }
final RelMetadataQuery mq = call.getMetadataQuery();
if (!SqlFunctions.isTrue(mq.areColumnsUnique(input,
aggregate.getGroupSet()))) {
return;
}
- // Distinct is "GROUP BY c1, c2" (where c1, c2 are a set of columns on
- // which the input is unique, i.e. contain a key) and has no aggregate
- // functions. It can be removed.
- final RelNode newInput = convert(input,
aggregate.getTraitSet().simplify());
- // If aggregate was projecting a subset of columns, add a project for the
- // same effect.
+ final RexBuilder rexBuilder = aggregate.getCluster().getRexBuilder();
+ final List<RexNode> projects = new LinkedList<>();
+ for (AggregateCall aggCall : aggregate.getAggCallList()) {
+ final SqlAggFunction aggregation = aggCall.getAggregation();
+ final SqlSplittableAggFunction splitter =
+ Objects.requireNonNull(
+ aggregation.unwrap(SqlSplittableAggFunction.class));
+ final RexNode singleton = splitter.singleton(
+ rexBuilder, input.getRowType(), aggCall);
+ projects.add(singleton);
+ }
+
+ final RelNode newInput = convert(input,
aggregate.getTraitSet().simplify());
final RelBuilder relBuilder = call.builder();
relBuilder.push(newInput);
- if (newInput.getRowType().getFieldCount()
+ if (!projects.isEmpty()) {
+ projects.addAll(0, relBuilder.fields(aggregate.getGroupSet().asList()));
+ relBuilder.project(projects);
+ } else if (newInput.getRowType().getFieldCount()
> aggregate.getRowType().getFieldCount()) {
+ // If aggregate was projecting a subset of columns, and there were no
+ // aggregate functions, add a project for the same effect.
relBuilder.project(relBuilder.fields(aggregate.getGroupSet().asList()));
}
- call.transformTo(relBuilder.build());
+ final RelNode newRel = relBuilder.build();
+ call.transformTo(newRel);
Review comment:
the variable doesn't seem necessary
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