fix: Fix bug where prefix matching fails when wildcards are in prefix (#40020)

issue: #40019

---------

Signed-off-by: Cai Zhang <cai.zhang@zilliz.com>

internal/parser/planparserv2/pattern_match.go

@@ -1,6 +1,8 @@
 package planparserv2
 
 import (
+	"strings"
+
 	"github.com/milvus-io/milvus/pkg/v2/proto/planpb"
 )
 
@@ -12,20 +14,27 @@ var wildcards = map[byte]struct{}{
 var escapeCharacter byte = '\\'
 
 // hasWildcards returns true if pattern contains any wildcard.
-func hasWildcards(pattern string) bool {
-	l := len(pattern)
-	i := l - 1
-	for ; i >= 0; i-- {
-		_, ok := wildcards[pattern[i]]
-		if ok {
-			if i > 0 && pattern[i-1] == escapeCharacter {
-				i--
+func hasWildcards(pattern string) (string, bool) {
+	var result strings.Builder
+	hasWildcard := false
+
+	for i := 0; i < len(pattern); i++ {
+		if pattern[i] == escapeCharacter && i+1 < len(pattern) {
+			next := pattern[i+1]
+			if _, ok := wildcards[next]; ok {
+				result.WriteByte(next)
+				i++
 				continue
 			}
-			return true
 		}
+
+		if _, ok := wildcards[pattern[i]]; ok {
+			hasWildcard = true
+		}
+		result.WriteByte(pattern[i])
 	}
-	return false
+
+	return result.String(), hasWildcard
 }
 
 // findLastNotOfWildcards find the last location not of last wildcard.
@@ -55,14 +64,14 @@ func translatePatternMatch(pattern string) (op planpb.OpType, operand string, er
 		return planpb.OpType_PrefixMatch, "", nil
 	}
 
-	exist := hasWildcards(pattern[:loc+1])
+	newPattern, exist := hasWildcards(pattern[:loc+1])
 	if loc >= l-1 && !exist {
 		// equal match.
-		return planpb.OpType_Equal, pattern, nil
+		return planpb.OpType_Equal, newPattern, nil
 	}
 	if !exist {
 		// prefix match.
-		return planpb.OpType_PrefixMatch, pattern[:loc+1], nil
+		return planpb.OpType_PrefixMatch, newPattern, nil
 	}
 
 	return planpb.OpType_Match, pattern, nil

internal/parser/planparserv2/pattern_match_test.go

@@ -11,38 +11,44 @@ func Test_hasWildcards(t *testing.T) {
 		pattern string
 	}
 	tests := []struct {
-		name string
-		args args
-		want bool
+		name   string
+		args   args
+		want   bool
+		target string
 	}{
 		{
 			args: args{
 				pattern: "no-wildcards",
 			},
-			want: false,
+			want:   false,
+			target: "no-wildcards",
 		},
 		{
 			args: args{
 				pattern: "has\\%",
 			},
-			want: false,
+			want:   false,
+			target: "has%",
 		},
 		{
 			args: args{
 				pattern: "%",
 			},
-			want: true,
+			want:   true,
+			target: "%",
 		},
 		{
 			args: args{
 				pattern: "has%",
 			},
-			want: true,
+			want:   true,
+			target: "has%",
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			if got := hasWildcards(tt.args.pattern); got != tt.want {
+			patten, got := hasWildcards(tt.args.pattern)
+			if got != tt.want || patten != tt.target {
 				t.Errorf("hasWildcards(%s) = %v, want %v", tt.args.pattern, got, tt.want)
 			}
 		})

internal/parser/planparserv2/plan_parser_v2_test.go

@@ -204,25 +204,44 @@ func TestExpr_Like(t *testing.T) {
 	helper, err := typeutil.CreateSchemaHelper(schema)
 	assert.NoError(t, err)
 
-	exprStrs := []string{
-		`VarCharField like "prefix%"`,
-		`VarCharField like "equal"`,
-		`JSONField["A"] like "name*"`,
-		`$meta["A"] like "name*"`,
-	}
-	for _, exprStr := range exprStrs {
-		assertValidExpr(t, helper, exprStr)
-	}
+	expr := `A like "8\\_0%"`
+	plan, err := CreateSearchPlan(helper, expr, "FloatVectorField", &planpb.QueryInfo{
+		Topk:         0,
+		MetricType:   "",
+		SearchParams: "",
+		RoundDecimal: 0,
+	}, nil)
+	assert.NoError(t, err, expr)
+	assert.NotNil(t, plan)
+	fmt.Println(plan)
+	assert.Equal(t, planpb.OpType_PrefixMatch, plan.GetVectorAnns().GetPredicates().GetUnaryRangeExpr().GetOp())
+	assert.Equal(t, "8_0", plan.GetVectorAnns().GetPredicates().GetUnaryRangeExpr().GetValue().GetStringVal())
 
-	// TODO: enable these after regex-match is supported.
-	//unsupported := []string{
-	//	`VarCharField like "not_%_supported"`,
-	//	`JSONField["A"] like "not_%_supported"`,
-	//	`$meta["A"] like "not_%_supported"`,
-	//}
-	//for _, exprStr := range unsupported {
-	//	assertInvalidExpr(t, helper, exprStr)
-	//}
+	expr = `A like "8_\\_0%"`
+	plan, err = CreateSearchPlan(helper, expr, "FloatVectorField", &planpb.QueryInfo{
+		Topk:         0,
+		MetricType:   "",
+		SearchParams: "",
+		RoundDecimal: 0,
+	}, nil)
+	assert.NoError(t, err, expr)
+	assert.NotNil(t, plan)
+	fmt.Println(plan)
+	assert.Equal(t, planpb.OpType_Match, plan.GetVectorAnns().GetPredicates().GetUnaryRangeExpr().GetOp())
+	assert.Equal(t, `8_\_0%`, plan.GetVectorAnns().GetPredicates().GetUnaryRangeExpr().GetValue().GetStringVal())
+
+	expr = `A like "8\\%-0%"`
+	plan, err = CreateSearchPlan(helper, expr, "FloatVectorField", &planpb.QueryInfo{
+		Topk:         0,
+		MetricType:   "",
+		SearchParams: "",
+		RoundDecimal: 0,
+	}, nil)
+	assert.NoError(t, err, expr)
+	assert.NotNil(t, plan)
+	fmt.Println(plan)
+	assert.Equal(t, planpb.OpType_PrefixMatch, plan.GetVectorAnns().GetPredicates().GetUnaryRangeExpr().GetOp())
+	assert.Equal(t, `8%-0`, plan.GetVectorAnns().GetPredicates().GetUnaryRangeExpr().GetValue().GetStringVal())
 }
 
 func TestExpr_TextMatch(t *testing.T) {