silundong commented on code in PR #4495:
URL: https://github.com/apache/calcite/pull/4495#discussion_r2290409739
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core/src/main/java/org/apache/calcite/tools/RelBuilder.java:
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@@ -2856,49 +2877,105 @@ private RelBuilder
rewriteAggregateWithDuplicateGroupSets(
}
}
- // AggregateCall list without GROUP_ID function
- final List<AggCall> aggregateCallsWithoutGroupId =
- new ArrayList<>(aggregateCalls);
- aggregateCallsWithoutGroupId.removeIf(RelBuilder::isGroupId);
+ // Create aggregate for each GROUP_ID value
+ for (Map.Entry<Integer, Set<ImmutableBitSet>> entry :
groupIdToGroupSets.entrySet()) {
+ // If n duplicates exist for a particular grouping, the {@code
GROUP_ID()}
+ // function produces values in the range 0 to n-1. For each value,
+ // we need to figure out the corresponding group sets.
+ //
+ // For example, "... GROUPING SETS (a, a, b, c, c, c, c)"
+ // (i) The max value of the GROUP_ID() function returns is 3
+ // (ii) GROUPING SETS (a, b, c) produces value 0,
+ // GROUPING SETS (a, c) produces value 1,
+ // GROUPING SETS (c) produces value 2
+ // GROUPING SETS (c) produces value 3
+ int groupId = entry.getKey();
+ Set<ImmutableBitSet> newGroupSets = entry.getValue();
+ rewriteGroupAggCalls(newGroupSets, groupSet, aggregateCalls, groupCount,
+ fieldNamesIfNoRewrite, mapping, input, groupId);
+ }
- // For each group id value, we first construct an Aggregate without
- // GROUP_ID() function call, and then create a Project node on top of it.
- // The Project adds literal value for group id in right position.
- final Frame frame = stack.pop();
- for (int groupId = 0; groupId <= maxGroupId; groupId++) {
- // Create the Aggregate node without GROUP_ID() call
- stack.push(frame);
- aggregate(groupKey(groupSet,
castNonNull(groupIdToGroupSets.get(groupId))),
- aggregateCallsWithoutGroupId);
-
- final List<RexNode> selectList = new ArrayList<>();
- final int groupExprLength = groupSet.cardinality();
- // Project fields in group by expressions
- for (int i = 0; i < groupExprLength; i++) {
- selectList.add(field(i));
- }
- // Project fields in aggregate calls
- int groupIdCount = 0;
- for (int i = 0; i < aggregateCalls.size(); i++) {
- if (isGroupId(aggregateCalls.get(i))) {
- selectList.add(
- getRexBuilder().makeExactLiteral(BigDecimal.valueOf(groupId),
- getTypeFactory().createSqlType(SqlTypeName.BIGINT)));
- groupIdCount++;
- } else {
- selectList.add(field(groupExprLength + i - groupIdCount));
- }
+ return union(true, groupIdToGroupSets.size());
+ }
+
+ /**
+ * Rewrite aggregate calls with special handling for GROUPING and GROUP_ID
functions,
+ * including NULL padding for missing grouping fields.
+ *
+ * @param groupSets The groupSets to use for this aggregate
+ * @param groupSet The groupSet to use for this aggregate
+ * @param aggregateCalls List of aggregate calls for this aggregate
+ * @param originalGroupCount The original groupSet size
+ * @param fieldNames Field names for the output row type
+ * @param mapping Field index mapping between input and output
+ * @param input The input relational expression
+ * @param groupId The GROUP_ID value to use for this aggregate
+ */
+ private void rewriteGroupAggCalls(Set<ImmutableBitSet> groupSets,
ImmutableBitSet groupSet,
+ List<AggregateCall> aggregateCalls, int originalGroupCount, List<String>
fieldNames,
+ Mappings.TargetMapping mapping, Frame input, int groupId) {
+ stack.push(input);
+
+ // specialFields records special values and their indexes.
+ // For example, GROUP_ID or GROUPING will be treated as
+ // numeric literals or NULL literals.
+ Map<Integer, RexNode> specialFields = new HashMap<>();
+ List<AggregateCall> aggCalls = new ArrayList<>();
+ for (int i = 0; i < aggregateCalls.size(); i++) {
+ AggregateCall aggCall = aggregateCalls.get(i);
+ switch (aggCall.getAggregation().getKind()) {
+ case GROUPING:
+ int grouping = calculateGroupingValue(groupSets.iterator().next(),
aggCall.getArgList());
+ specialFields.put(originalGroupCount + i,
+ getRexBuilder().makeLiteral(grouping, aggCall.getType(), true));
+ break;
+ case GROUP_ID:
+ specialFields.put(originalGroupCount + i,
+ getRexBuilder().makeLiteral(groupId, aggCall.getType()));
+ break;
+ default:
+ aggCalls.add(aggCall);
Review Comment:
Should AggregateCall be rebuild here? Its nullability may change from true
to false.
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