milvus/internal/util/function/rerank/rrf_function.go
junjiejiangjjj 71563d5d0e
enhance: optimize decay function with configurable score merging and … (#44066)
…normalization

- Add configurable score merge functions (max, avg, sum) for decay
reranking
- Introduce norm_score parameter to control score normalization behavior
- Refactor score normalization logic into reusable utility functions

#44051

Signed-off-by: junjie.jiang <junjie.jiang@zilliz.com>
2025-09-23 14:18:06 +08:00

102 lines
3.0 KiB
Go

/*
* # Licensed to the LF AI & Data foundation under one
* # or more contributor license agreements. See the NOTICE file
* # distributed with this work for additional information
* # regarding copyright ownership. The ASF licenses this file
* # to you under the Apache License, Version 2.0 (the
* # "License"); you may not use this file except in compliance
* # with the License. You may obtain a copy of the License at
* #
* # http://www.apache.org/licenses/LICENSE-2.0
* #
* # Unless required by applicable law or agreed to in writing, software
* # distributed under the License is distributed on an "AS IS" BASIS,
* # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* # See the License for the specific language governing permissions and
* # limitations under the License.
*/
package rerank
import (
"context"
"fmt"
"strconv"
"strings"
"github.com/milvus-io/milvus-proto/go-api/v2/schemapb"
)
const (
RRFParamsKey string = "k"
defaultRRFParamsValue float64 = 60
)
type RRFFunction[T PKType] struct {
RerankBase
k float32
}
func newRRFFunction(collSchema *schemapb.CollectionSchema, funcSchema *schemapb.FunctionSchema) (Reranker, error) {
base, err := newRerankBase(collSchema, funcSchema, RRFName, true)
if err != nil {
return nil, err
}
if len(base.GetInputFieldNames()) != 0 {
return nil, fmt.Errorf("The rrf function does not support input parameters, but got %s", base.GetInputFieldNames())
}
k := float64(defaultRRFParamsValue)
for _, param := range funcSchema.Params {
if strings.ToLower(param.Key) == RRFParamsKey {
if k, err = strconv.ParseFloat(param.Value, 64); err != nil {
return nil, fmt.Errorf("Param k:%s is not a number", param.Value)
}
}
}
if k <= 0 || k >= 16384 {
return nil, fmt.Errorf("The rank params k should be in range (0, %d)", 16384)
}
if base.pkType == schemapb.DataType_Int64 {
return &RRFFunction[int64]{RerankBase: *base, k: float32(k)}, nil
} else {
return &RRFFunction[string]{RerankBase: *base, k: float32(k)}, nil
}
}
func (rrf *RRFFunction[T]) processOneSearchData(ctx context.Context, searchParams *SearchParams, cols []*columns, idGroup map[any]any) (*IDScores[T], error) {
rrfScores := map[T]float32{}
for _, col := range cols {
if col.size == 0 {
continue
}
ids := col.ids.([]T)
for idx, id := range ids {
if score, ok := rrfScores[id]; !ok {
rrfScores[id] = 1 / (rrf.k + float32(idx+1))
} else {
rrfScores[id] = score + 1/(rrf.k+float32(idx+1))
}
}
}
if searchParams.isGrouping() {
return newGroupingIDScores(rrfScores, searchParams, idGroup)
}
return newIDScores(rrfScores, searchParams, true), nil
}
func (rrf *RRFFunction[T]) Process(ctx context.Context, searchParams *SearchParams, inputs *rerankInputs) (*rerankOutputs, error) {
outputs := newRerankOutputs(searchParams)
for _, cols := range inputs.data {
idScore, err := rrf.processOneSearchData(ctx, searchParams, cols, inputs.idGroupValue)
if err != nil {
return nil, err
}
appendResult(outputs, idScore.ids, idScore.scores)
}
return outputs, nil
}