92 lines
2.7 KiB
Go
92 lines
2.7 KiB
Go
// Copyright 2024 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package expression
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import (
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"strings"
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"github.com/pingcap/tidb/pkg/parser/ast"
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"github.com/pingcap/tidb/pkg/parser/model"
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"github.com/pingcap/tidb/pkg/parser/mysql"
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"github.com/pingcap/tidb/pkg/types"
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"github.com/pingcap/tidb/pkg/util/intest"
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"github.com/pingcap/tipb/go-tipb"
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)
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var (
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vsDistanceFnNamesLower = map[string]struct{}{
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strings.ToLower(ast.VecL1Distance): {},
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strings.ToLower(ast.VecL2Distance): {},
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strings.ToLower(ast.VecCosineDistance): {},
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strings.ToLower(ast.VecNegativeInnerProduct): {},
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}
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)
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// VectorHelper is a helper struct for vector indexes.
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type VectorHelper struct {
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DistanceFnName model.CIStr
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FnPbCode tipb.ScalarFuncSig
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Vec types.VectorFloat32
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Column *Column
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}
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// ExtractVectorHelper extracts a VectorSearchExpr from an expression.
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// NOTE: not all VectorSearch functions are supported by the index. The caller
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// needs to check the distance function name.
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func ExtractVectorHelper(expr Expression) *VectorHelper {
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x, ok := expr.(*ScalarFunction)
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if !ok {
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return nil
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}
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if _, isVecFn := vsDistanceFnNamesLower[x.FuncName.L]; !isVecFn {
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return nil
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}
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args := x.GetArgs()
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// One arg must be a vector column ref, and one arg must be a vector constant.
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var vectorConstant *Constant = nil
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var vectorColumn *Column = nil
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nVectorColumns := 0
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nVectorConstants := 0
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for _, arg := range args {
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if v, ok := arg.(*Column); ok {
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if v.RetType.GetType() != mysql.TypeTiDBVectorFloat32 {
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return nil
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}
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vectorColumn = v
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nVectorColumns++
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} else if v, ok := arg.(*Constant); ok {
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if v.RetType.GetType() != mysql.TypeTiDBVectorFloat32 {
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return nil
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}
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vectorConstant = v
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nVectorConstants++
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}
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}
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if nVectorColumns != 1 || nVectorConstants != 1 {
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return nil
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}
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intest.Assert(vectorConstant.Value.Kind() == types.KindVectorFloat32, "internal: expect vectorFloat32 constant, but got %s", vectorConstant.Value.String())
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return &VectorHelper{
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DistanceFnName: x.FuncName,
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FnPbCode: x.Function.PbCode(),
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Vec: vectorConstant.Value.GetVectorFloat32(),
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Column: vectorColumn,
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}
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}
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