planner: optimize the parameterization(parser.Restore) performance for non-prep plan cache (#43018)

ref pingcap/tidb#36598

parser/format/format.go

@@ -349,16 +349,22 @@ func (rf RestoreFlags) HasRestoreForNonPrepPlanCache() bool {
 	return rf.has(RestoreForNonPrepPlanCache)
 }
 
+// RestoreWriter is the interface for `Restore` to write.
+type RestoreWriter interface {
+	io.Writer
+	io.StringWriter
+}
+
 // RestoreCtx is `Restore` context to hold flags and writer.
 type RestoreCtx struct {
 	Flags     RestoreFlags
-	In        io.Writer
+	In        RestoreWriter
 	DefaultDB string
 	CTERestorer
 }
 
 // NewRestoreCtx returns a new `RestoreCtx`.
-func NewRestoreCtx(flags RestoreFlags, in io.Writer) *RestoreCtx {
+func NewRestoreCtx(flags RestoreFlags, in RestoreWriter) *RestoreCtx {
 	return &RestoreCtx{Flags: flags, In: in, DefaultDB: ""}
 }
 
@@ -427,12 +433,16 @@ func (ctx *RestoreCtx) WriteName(name string) {
 		name = strings.Replace(name, "`", "``", -1)
 		quotes = "`"
 	}
-	fmt.Fprint(ctx.In, quotes, name, quotes)
+
+	// use `WriteString` directly instead of `fmt.Fprint` to get a better performance.
+	ctx.In.WriteString(quotes)
+	ctx.In.WriteString(name)
+	ctx.In.WriteString(quotes)
 }
 
 // WritePlain writes the plain text into writer without any handling.
 func (ctx *RestoreCtx) WritePlain(plainText string) {
-	fmt.Fprint(ctx.In, plainText)
+	ctx.In.WriteString(plainText)
 }
 
 // WritePlainf write the plain text into writer without any handling.

planner/core/plan_cache_param.go

@@ -15,9 +15,9 @@
 package core
 
 import (
+	"bytes"
 	"context"
 	"errors"
-	"strings"
 	"sync"
 
 	"github.com/pingcap/tidb/expression"
@@ -41,8 +41,7 @@ var (
 		return pr
 	}}
 	paramCtxPool = sync.Pool{New: func() interface{} {
-		buf := new(strings.Builder)
-		buf.Reset()
+		buf := new(bytes.Buffer)
 		restoreCtx := format.NewRestoreCtx(format.RestoreForNonPrepPlanCache|format.RestoreStringWithoutCharset|format.RestoreStringSingleQuotes|format.RestoreNameBackQuotes, buf)
 		return restoreCtx
 	}}
@@ -106,14 +105,14 @@ func ParameterizeAST(ctx context.Context, sctx sessionctx.Context, stmt ast.Stmt
 	defer func() {
 		pr.Reset()
 		paramReplacerPool.Put(pr)
-		pCtx.In.(*strings.Builder).Reset()
+		pCtx.In.(*bytes.Buffer).Reset()
 		paramCtxPool.Put(pCtx)
 	}()
 	stmt.Accept(pr)
 	if err := stmt.Restore(pCtx); err != nil {
 		return "", nil, err
 	}
-	paramSQL, params = pCtx.In.(*strings.Builder).String(), pr.params
+	paramSQL, params = pCtx.In.(*bytes.Buffer).String(), pr.params
 	return
 }