Revert "reduce memory usage of building insert values"

This reverts commit 0363d4a.

common.go

@@ -94,25 +94,17 @@ func commaTables(scope scope, tables []Table) string {
 	return sqlBuilder.String()
 }
 
-func commaValuesBuilder(scope scope, builder *strings.Builder, values []interface{}) error {
-	builder.Grow(16 * (len(values) + 2)) // hopefully reduce copying
+func commaValues(scope scope, values []interface{}) (string, error) {
+	var sqlBuilder strings.Builder
 	for i, item := range values {
 		if i > 0 {
-			builder.WriteString(", ")
+			sqlBuilder.WriteString(", ")
 		}
 		itemSql, _, err := getSQL(scope, item)
 		if err != nil {
-			return err
+			return "", err
 		}
-		builder.WriteString(itemSql)
-	}
-	return nil
-}
-
-func commaValues(scope scope, values []interface{}) (string, error) {
-	var sqlBuilder strings.Builder
-	if err := commaValuesBuilder(scope, &sqlBuilder, values); err != nil {
-		return "", err
+		sqlBuilder.WriteString(itemSql)
 	}
 	return sqlBuilder.String(), nil
 }

insert.go

@@ -6,7 +6,6 @@ import (
 	"errors"
 	"fmt"
 	"reflect"
-	"strings"
 )
 
 type insertStatus struct {
@@ -139,7 +138,7 @@ func (s insertStatus) OnDuplicateKeyIgnore() toInsertFinal {
 
 func (s insertStatus) GetSQL() (string, error) {
 	var fields []Field
-	var valuesBuilder strings.Builder
+	var values []interface{}
 	if len(s.models) > 0 {
 		models := make([]Model, 0, len(s.models))
 		for _, model := range s.models {
@@ -150,19 +149,11 @@ func (s insertStatus) GetSQL() (string, error) {
 
 		if len(models) > 0 {
 			fields = models[0].GetTable().GetFields()
-			valuesBuilder.Grow(64 * len(models))
-			for i, model := range models {
+			for _, model := range models {
 				if model.GetTable().GetName() != s.scope.Tables[0].GetName() {
 					return "", errors.New("invalid table from model")
 				}
-				if i > 0 {
-					valuesBuilder.WriteString(", ")
-				}
-				valuesBuilder.WriteString("(")
-				if err := commaValuesBuilder(s.scope, &valuesBuilder, model.GetValues()); err != nil {
-					return "", err
-				}
-				valuesBuilder.WriteString(")")
+				values = append(values, model.GetValues())
 			}
 		}
 	} else {
@@ -171,12 +162,10 @@ func (s insertStatus) GetSQL() (string, error) {
 		} else {
 			fields = s.fields
 		}
-		if err := commaValuesBuilder(s.scope, &valuesBuilder, s.values); err != nil {
-			return "", err
-		}
+		values = s.values
 	}
 
-	if valuesBuilder.Len() == 0 {
+	if len(values) == 0 {
 		return "/* INSERT without VALUES */ DO 0", nil
 	}
 
@@ -185,8 +174,12 @@ func (s insertStatus) GetSQL() (string, error) {
 	if err != nil {
 		return "", err
 	}
+	valuesSql, err := commaValues(s.scope, values)
+	if err != nil {
+		return "", err
+	}
 
-	sqlString := s.method + " INTO " + tableSql + " (" + fieldsSql + ") VALUES " + valuesBuilder.String()
+	sqlString := s.method + " INTO " + tableSql + " (" + fieldsSql + ") VALUES " + valuesSql
 	if len(s.onDuplicateKeyUpdateAssignments) > 0 {
 		assignmentsSql, err := commaAssignments(s.scope, s.onDuplicateKeyUpdateAssignments)
 		if err != nil {