milvus/internal/proxy/agg_reducer.go
Chun Han b7ee93fc52
feat: support query aggregtion(#36380) (#44394)
related: #36380

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
- Core invariant: aggregation is centralized and schema-aware — all
aggregate functions are created via the exec Aggregate registry
(milvus::exec::Aggregate) and validated by ValidateAggFieldType, use a
single in-memory accumulator layout (Accumulator/RowContainer) and
grouping primitives (GroupingSet, HashTable, VectorHasher), ensuring
consistent typing, null semantics and offsets across planner → exec →
reducer conversion paths (toAggregateInfo, Aggregate::create,
GroupingSet, AggResult converters).

- Removed / simplified logic: removed ad‑hoc count/group-by and reducer
code (CountNode/PhyCountNode, GroupByNode/PhyGroupByNode, cntReducer and
its tests) and consolidated into a unified AggregationNode →
PhyAggregationNode + GroupingSet + HashTable execution path and
centralized reducers (MilvusAggReducer, InternalAggReducer,
SegcoreAggReducer). AVG now implemented compositionally (SUM + COUNT)
rather than a bespoke operator, eliminating duplicate implementations.

- Why this does NOT cause data loss or regressions: existing data-access
and serialization paths are preserved and explicitly validated —
bulk_subscript / bulk_script_field_data and FieldData creation are used
for output materialization; converters (InternalResult2AggResult ↔
AggResult2internalResult, SegcoreResults2AggResult ↔
AggResult2segcoreResult) enforce shape/type/row-count validation; proxy
and plan-level checks (MatchAggregationExpression,
translateOutputFields, ValidateAggFieldType, translateGroupByFieldIds)
reject unsupported inputs (ARRAY/JSON, unsupported datatypes) early.
Empty-result generation and explicit error returns guard against silent
corruption.

- New capability and scope: end-to-end GROUP BY and aggregation support
added across the stack — proto (plan.proto, RetrieveRequest fields
group_by_field_ids/aggregates), planner nodes (AggregationNode,
ProjectNode, SearchGroupByNode), exec operators (PhyAggregationNode,
PhyProjectNode) and aggregation core (Aggregate implementations:
Sum/Count/Min/Max, SimpleNumericAggregate, RowContainer, GroupingSet,
HashTable) plus proxy/querynode reducers and tests — enabling grouped
and global aggregation (sum, count, min, max, avg via sum+count) with
schema-aware validation and reduction.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Signed-off-by: MrPresent-Han <chun.han@gmail.com>
Co-authored-by: MrPresent-Han <chun.han@gmail.com>
2026-01-06 16:29:25 +08:00

66 lines
2.4 KiB
Go

package proxy
import (
"context"
"fmt"
"github.com/milvus-io/milvus-proto/go-api/v2/milvuspb"
"github.com/milvus-io/milvus-proto/go-api/v2/schemapb"
"github.com/milvus-io/milvus/internal/agg"
"github.com/milvus-io/milvus/pkg/v2/proto/internalpb"
"github.com/milvus-io/milvus/pkg/v2/proto/planpb"
"github.com/milvus-io/milvus/pkg/v2/util/merr"
)
type MilvusAggReducer struct {
groupAggReducer *agg.GroupAggReducer
outputMap *agg.AggregationFieldMap
}
func NewMilvusAggReducer(groupByFieldIds []int64, aggregates []*planpb.Aggregate,
outputMap *agg.AggregationFieldMap, groupLimit int64, schema *schemapb.CollectionSchema,
) *MilvusAggReducer {
// must ensure outputMap is not nil outside
// Default groupLimit to -1 (no limit) if groupLimit <= 0
if groupLimit <= 0 {
groupLimit = -1
}
return &MilvusAggReducer{
agg.NewGroupAggReducer(groupByFieldIds, aggregates, groupLimit, schema),
outputMap,
}
}
func (reducer *MilvusAggReducer) Reduce(results []*internalpb.RetrieveResults) (*milvuspb.QueryResults, error) {
reducedAggRes, err := reducer.groupAggReducer.Reduce(context.Background(), agg.InternalResult2AggResult(results))
if err != nil {
return nil, err
}
fieldCount := reducer.outputMap.Count()
reOrganizedFieldDatas := make([]*schemapb.FieldData, fieldCount)
reducedFieldDatas := reducedAggRes.GetFieldDatas()
for i := 0; i < fieldCount; i++ {
indices := reducer.outputMap.IndexesAt(i)
if len(indices) == 0 {
return nil, fmt.Errorf("no indices found for output field at index %d", i)
} else if len(indices) == 1 {
// Single index: direct copy (non-avg aggregation or group-by field)
reOrganizedFieldDatas[i] = reducedFieldDatas[indices[0]]
reOrganizedFieldDatas[i].FieldName = reducer.outputMap.NameAt(i)
} else if len(indices) == 2 {
// Two indices: avg aggregation (sum and count)
sumFieldData := reducedFieldDatas[indices[0]]
countFieldData := reducedFieldDatas[indices[1]]
avgFieldData, err := agg.ComputeAvgFromSumAndCount(sumFieldData, countFieldData)
if err != nil {
return nil, fmt.Errorf("failed to compute avg for field %s: %w", reducer.outputMap.NameAt(i), err)
}
avgFieldData.FieldName = reducer.outputMap.NameAt(i)
reOrganizedFieldDatas[i] = avgFieldData
} else {
return nil, fmt.Errorf("unexpected number of indices (%d) for output field at index %d, expected 1 or 2", len(indices), i)
}
}
return &milvuspb.QueryResults{FieldsData: reOrganizedFieldDatas, Status: merr.Success()}, nil
}