From ae9af89c4ad0866f398c9bb23fc1df210a532993 Mon Sep 17 00:00:00 2001
From: Yujie Xia <xiayjchn@gmail.com>
Date: Tue, 28 Jun 2022 14:24:48 +0800
Subject: [PATCH] lightning: avoid extracting db schema when schema file is not
 provided

---
 br/pkg/lightning/mydump/loader.go      | 26 ++++++++++++--------------
 br/pkg/lightning/mydump/loader_test.go |  8 ++++++--
 2 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/br/pkg/lightning/mydump/loader.go b/br/pkg/lightning/mydump/loader.go
index 30f4f14c1464c..40091c61b2d03 100644
--- a/br/pkg/lightning/mydump/loader.go
+++ b/br/pkg/lightning/mydump/loader.go
@@ -39,21 +39,19 @@ type MDDatabaseMeta struct {
 }
 
 func (m *MDDatabaseMeta) GetSchema(ctx context.Context, store storage.ExternalStorage) string {
-	schema, err := ExportStatement(ctx, store, m.SchemaFile, m.charSet)
-	if err != nil {
-		log.FromContext(ctx).Warn("failed to extract table schema",
-			zap.String("Path", m.SchemaFile.FileMeta.Path),
-			log.ShortError(err),
-		)
-		schema = nil
-	}
-	schemaStr := strings.TrimSpace(string(schema))
-	// set default if schema sql is empty
-	if len(schemaStr) == 0 {
-		schemaStr = "CREATE DATABASE IF NOT EXISTS " + common.EscapeIdentifier(m.Name)
+	if m.SchemaFile.FileMeta.Path != "" {
+		schema, err := ExportStatement(ctx, store, m.SchemaFile, m.charSet)
+		if err != nil {
+			log.FromContext(ctx).Warn("failed to extract table schema",
+				zap.String("Path", m.SchemaFile.FileMeta.Path),
+				log.ShortError(err),
+			)
+		} else if schemaStr := strings.TrimSpace(string(schema)); schemaStr != "" {
+			return schemaStr
+		}
 	}
-
-	return schemaStr
+	// set default if schema sql is empty or failed to extract.
+	return "CREATE DATABASE IF NOT EXISTS " + common.EscapeIdentifier(m.Name)
 }
 
 type MDTableMeta struct {
diff --git a/br/pkg/lightning/mydump/loader_test.go b/br/pkg/lightning/mydump/loader_test.go
index 0f7079a1f95df..e256a685f20ee 100644
--- a/br/pkg/lightning/mydump/loader_test.go
+++ b/br/pkg/lightning/mydump/loader_test.go
@@ -21,6 +21,7 @@ import (
 	"testing"
 
 	"github.com/pingcap/tidb/br/pkg/lightning/config"
+	"github.com/pingcap/tidb/br/pkg/lightning/log"
 	md "github.com/pingcap/tidb/br/pkg/lightning/mydump"
 	"github.com/pingcap/tidb/br/pkg/storage"
 	filter "github.com/pingcap/tidb/util/table-filter"
@@ -181,13 +182,16 @@ func TestTableInfoNotFound(t *testing.T) {
 	loader, err := md.NewMyDumpLoader(ctx, s.cfg)
 	require.NoError(t, err)
 	for _, dbMeta := range loader.GetDatabases() {
-		dbSQL := dbMeta.GetSchema(ctx, store)
+		logger, buffer := log.MakeTestLogger()
+		logCtx := log.NewContext(ctx, logger)
+		dbSQL := dbMeta.GetSchema(logCtx, store)
 		require.Equal(t, "CREATE DATABASE IF NOT EXISTS `db`", dbSQL)
 		for _, tblMeta := range dbMeta.Tables {
-			sql, err := tblMeta.GetSchema(ctx, store)
+			sql, err := tblMeta.GetSchema(logCtx, store)
 			require.Equal(t, "", sql)
 			require.NoError(t, err)
 		}
+		require.NotContains(t, buffer.Stripped(), "failed to extract table schema")
 	}
 }