infoschema: rewrite SchemaSimpleTableInfos for infoschema v2 to avoid…

… network (#55088)

ref #50959

pkg/infoschema/infoschema_v2.go

@@ -795,33 +795,34 @@ func (is *infoschemaV2) SchemaSimpleTableInfos(ctx context.Context, schema model
 		return nil, nil // something wrong?
 	}
 
-retry:
-	dbInfo, ok := is.SchemaByName(schema)
-	if !ok {
+	// Ascend is much more difficult than Descend.
+	// So the data is taken out first and then dedup in Descend order.
+	var tableItems []tableItem
+	is.byName.Ascend(tableItem{dbName: schema.L}, func(item tableItem) bool {
+		if item.dbName != schema.L {
+			return false
+		}
+		if is.infoSchema.schemaMetaVersion >= item.schemaVersion {
+			tableItems = append(tableItems, item)
+		}
+		return true
+	})
+	if len(tableItems) == 0 {
 		return nil, nil
 	}
-	snapshot := is.r.Store().GetSnapshot(kv.NewVersion(is.ts))
-	// Using the KV timeout read feature to address the issue of potential DDL lease expiration when
-	// the meta region leader is slow.
-	snapshot.SetOption(kv.TiKVClientReadTimeout, uint64(3000)) // 3000ms.
-	m := meta.NewSnapshotMeta(snapshot)
-	tblInfos, err := m.ListSimpleTables(dbInfo.ID)
-	if err != nil {
-		if meta.ErrDBNotExists.Equal(err) {
-			return nil, nil
-		}
-		// Flashback statement could cause such kind of error.
-		// In theory that error should be handled in the lower layer, like client-go.
-		// But it's not done, so we retry here.
-		if strings.Contains(err.Error(), "in flashback progress") {
-			select {
-			case <-time.After(200 * time.Millisecond):
-			case <-ctx.Done():
-				return nil, ctx.Err()
+	tblInfos := make([]*model.TableNameInfo, 0, len(tableItems))
+	var curr *tableItem
+	for i := len(tableItems) - 1; i >= 0; i-- {
+		item := &tableItems[i]
+		if curr == nil || curr.tableName != tableItems[i].tableName {
+			curr = item
+			if !item.tomb {
+				tblInfos = append(tblInfos, &model.TableNameInfo{
+					ID:   item.tableID,
+					Name: model.NewCIStr(item.tableName),
+				})
 			}
-			goto retry
 		}
-		return nil, errors.Trace(err)
 	}
 	return tblInfos, nil
 }

pkg/infoschema/test/infoschemav2test/BUILD.bazel

@@ -8,7 +8,7 @@ go_test(
         "v2_test.go",
     ],
     flaky = True,
-    shard_count = 8,
+    shard_count = 9,
     deps = [
         "//pkg/domain",
         "//pkg/domain/infosync",

pkg/infoschema/test/infoschemav2test/v2_test.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"fmt"
 	"slices"
+	"sort"
 	"strconv"
 	"strings"
 	"testing"
@@ -428,3 +429,60 @@ func TestIssue54926(t *testing.T) {
 	require.Equal(t, time2TS, tk.Session().GetSessionVars().TxnReadTS.PeakTxnReadTS())
 	require.Equal(t, schemaVer2, tk.Session().GetInfoSchema().SchemaMetaVersion())
 }
+
+func TestSchemaSimpleTableInfos(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	// For mocktikv, safe point is not initialized, we manually insert it for snapshot to use.
+	safePointName := "tikv_gc_safe_point"
+	safePointValue := "20160102-15:04:05 -0700"
+	safePointComment := "All versions after safe point can be accessed. (DO NOT EDIT)"
+	updateSafePoint := fmt.Sprintf(`INSERT INTO mysql.tidb VALUES ('%[1]s', '%[2]s', '%[3]s')
+	ON DUPLICATE KEY
+	UPDATE variable_value = '%[2]s', comment = '%[3]s'`, safePointName, safePointValue, safePointComment)
+	tk.MustExec(updateSafePoint)
+	tk.MustExec("set @@global.tidb_schema_cache_size = '512MB'")
+
+	tk.MustExec("create database aaa")
+	tk.MustExec("create database zzz")
+	tk.MustExec("drop database zzz")
+
+	tk.MustExec("create database simple")
+	tk.MustExec("use simple")
+	tk.MustExec("create table t1 (id int)")
+	tk.MustExec("create table t2 (id int)")
+
+	time1 := time.Now()
+	time.Sleep(50 * time.Millisecond)
+
+	tk.MustExec("rename table simple.t2 to aaa.t2")
+	tk.MustExec("drop database aaa")
+
+	is := tk.Session().GetInfoSchema()
+	// Cover special schema
+	tblInfos, err := is.SchemaSimpleTableInfos(context.Background(), model.NewCIStr("INFORMATION_SCHEMA"))
+	require.NoError(t, err)
+	res := make([]string, 0, len(tblInfos))
+	for _, tbl := range tblInfos {
+		res = append(res, tbl.Name.L)
+	}
+	sort.Strings(res)
+	tk.MustQuery("select lower(table_name) from information_schema.tables where table_schema = 'information_schema'").
+		Sort().Check(testkit.Rows(res...))
+
+	// Cover normal schema
+	tblInfos, err = is.SchemaSimpleTableInfos(context.Background(), model.NewCIStr("simple"))
+	require.NoError(t, err)
+	require.Len(t, tblInfos, 1)
+	require.Equal(t, tblInfos[0].Name.L, "t1")
+
+	// Cover snapshot infoschema
+	tk.MustExec(fmt.Sprintf(`set @@tidb_snapshot="%s"`, time1.Format("2006-1-2 15:04:05.000")))
+	is = tk.Session().GetInfoSchema()
+	tblInfos, err = is.SchemaSimpleTableInfos(context.Background(), model.NewCIStr("simple"))
+	require.NoError(t, err)
+	require.Len(t, tblInfos, 2)
+	require.Equal(t, tblInfos[0].Name.L, "t2")
+	require.Equal(t, tblInfos[1].Name.L, "t1")
+}