perf(builder): replace fmt.Sprintf with string concatenation in hot paths

page.go

@@ -3,7 +3,6 @@ package pgkit
 import (
 	"cmp"
 	"context"
-	"fmt"
 	"regexp"
 	"slices"
 	"strings"
@@ -92,7 +91,7 @@ func (s Sort) String() string {
 	if s.Column == "" {
 		return ""
 	}
-	return fmt.Sprintf("%s %s", s.Column, s.Order)
+	return s.Column + " " + string(s.Order)
 }
 
 var _MatcherOrderBy = regexp.MustCompile(`-?([a-zA-Z0-9]+)`)
@@ -266,7 +265,7 @@ func (p Paginator[T]) getOrder(page *Page) []string {
 	sort := page.GetOrder(p.settings.ColumnFunc, p.settings.Sort...)
 	list := make([]string, len(sort))
 	for i := range sort {
-		list[i] = fmt.Sprintf("%s %s", sort[i].Column, sort[i].Order)
+		list[i] = sort[i].Column + " " + string(sort[i].Order)
 	}
 	return list
 }

querier.go

@@ -1,9 +1,9 @@
 package pgkit
 
 import (
-	"bytes"
 	"context"
 	"fmt"
+	"strconv"
 	"strings"
 
 	sq "github.com/Masterminds/squirrel"
@@ -260,14 +260,15 @@ func (r RawSQL) Prepare(query string) (string, int, error) {
 
 	parts := strings.Split(query, "?")
 
-	q := bytes.Buffer{}
+	q := strings.Builder{}
 	for i, p := range parts {
 		if p == "" {
 			continue
 		}
 		q.WriteString(p)
 		if i < n {
-			q.WriteString(fmt.Sprintf("$%d", i+1))
+			q.WriteByte('$')
+			q.WriteString(strconv.Itoa(i + 1))
 		}
 	}
 

stringconcat_bench_test.go

@@ -0,0 +1,47 @@
+package pgkit_test
+
+import (
+	"testing"
+
+	"github.com/goware/pgkit/v2"
+	"github.com/stretchr/testify/require"
+)
+
+// TestStringConcatOutputUnchanged pins the exact strings produced by the hot
+// query-building paths, so the fmt.Sprintf -> concatenation change is proven
+// to be output-preserving (must pass before and after the fix).
+func TestStringConcatOutputUnchanged(t *testing.T) {
+	// Columns are quoted by pgx.Identifier.Sanitize().
+	require.Equal(t, `"created_at" DESC`, pgkit.Sort{Column: "created_at", Order: pgkit.Desc}.String())
+	require.Equal(t, `"name" ASC`, pgkit.Sort{Column: "name", Order: pgkit.Asc}.String())
+	// Unset order defaults to ASC via sanitize.
+	require.Equal(t, `"id" ASC`, pgkit.Sort{Column: "id"}.String())
+
+	stmt := pgkit.RawQuery("SELECT * FROM t WHERE a = ? AND b = ? AND c = ?")
+	require.NoError(t, stmt.Err())
+	require.Equal(t, "SELECT * FROM t WHERE a = $1 AND b = $2 AND c = $3", stmt.GetQuery())
+	require.Equal(t, 3, stmt.NumArgs())
+}
+
+// BenchmarkSortString measures Sort.String(), called once per ORDER BY column
+// on every paginated and keyset query build.
+func BenchmarkSortString(b *testing.B) {
+	s := pgkit.Sort{Column: "created_at", Order: pgkit.Desc}
+	b.ReportAllocs()
+	for b.Loop() {
+		_ = s.String()
+	}
+}
+
+// BenchmarkRawQueryPrepare measures RawQuery, which runs the placeholder
+// rewrite (?-> $N) in RawSQL.Prepare once per call.
+func BenchmarkRawQueryPrepare(b *testing.B) {
+	const q = "SELECT * FROM t WHERE a = ? AND b = ? AND c = ? AND d = ? AND e = ?"
+	b.ReportAllocs()
+	for b.Loop() {
+		stmt := pgkit.RawQuery(q)
+		if stmt.Err() != nil {
+			b.Fatal(stmt.Err())
+		}
+	}
+}