infoschema: don't load table info to get auto_increment value

pkg/executor/infoschema_reader.go

@@ -242,11 +242,26 @@ func getAutoIncrementID(
 	sctx sessionctx.Context,
 	tblInfo *model.TableInfo,
 ) int64 {
+	if raw, ok := is.(*infoschema.SessionExtendedInfoSchema); ok {
+		if ok, v2 := infoschema.IsV2(raw.InfoSchema); ok {
+			isCached := v2.TableIsCached(tblInfo.ID)
+			if !isCached {
+				// Loading table info from kv storage invalidates the cached auto_increment id.
+				return 0
+			}
+		}
+	}
 	tbl, ok := is.TableByID(context.Background(), tblInfo.ID)
 	if !ok {
 		return 0
 	}
-	return tbl.Allocators(sctx.GetTableCtx()).Get(autoid.AutoIncrementType).Base() + 1
+	alloc := tbl.Allocators(sctx.GetTableCtx()).Get(autoid.AutoIncrementType)
+	if alloc == nil || alloc.Base() == 0 {
+		// It may not be loaded yet.
+		// To show global next autoID, one should use `show table x next_row_id`.
+		return 0
+	}
+	return alloc.Base() + 1
 }
 
 func hasPriv(ctx sessionctx.Context, priv mysql.PrivilegeType) bool {

pkg/infoschema/infoschema_v2.go

@@ -691,6 +691,31 @@ func (is *infoschemaV2) IterateAllTableItems(visit func(TableItem) bool) {
 	})
 }
 
+// TableIsCached checks whether the table is cached.
+func (is *infoschemaV2) TableIsCached(id int64) (ok bool) {
+	if !tableIDIsValid(id) {
+		return false
+	}
+
+	itm, ok := is.searchTableItemByID(id)
+	if !ok {
+		return false
+	}
+
+	if isTableVirtual(id) {
+		if raw, exist := is.Data.specials.Load(itm.dbName.L); exist {
+			schTbls := raw.(*schemaTables)
+			_, ok = schTbls.tables[itm.tableName.L]
+			return ok
+		}
+		return false
+	}
+
+	key := tableCacheKey{itm.tableID, itm.schemaVersion}
+	tbl, found := is.tableCache.Get(key)
+	return found && tbl != nil
+}
+
 // IsSpecialDB tells whether the database is a special database.
 func IsSpecialDB(dbName string) bool {
 	return dbName == util.InformationSchemaName.L ||

pkg/infoschema/test/clustertablestest/tables_test.go

@@ -93,7 +93,7 @@ func TestInfoSchemaFieldValue(t *testing.T) {
 	tk.MustExec("drop table if exists t")
 	tk.MustExec("create table t (c int auto_increment primary key, d int)")
 	tk.MustQuery("select auto_increment from information_schema.tables where table_name='t'").Check(
-		testkit.Rows("1"))
+		testkit.Rows("0"))
 	tk.MustExec("insert into t(c, d) values(1, 1)")
 	tk.MustQuery("select auto_increment from information_schema.tables where table_name='t'").Check(
 		testkit.Rows("2"))

pkg/infoschema/test/infoschemav2test/BUILD.bazel

@@ -8,12 +8,13 @@ go_test(
         "v2_test.go",
     ],
     flaky = True,
-    shard_count = 11,
+    shard_count = 12,
     deps = [
         "//pkg/domain",
         "//pkg/domain/infosync",
         "//pkg/infoschema",
         "//pkg/infoschema/context",
+        "//pkg/meta/autoid",
         "//pkg/parser/auth",
         "//pkg/parser/model",
         "//pkg/sessionctx/variable",

pkg/infoschema/test/infoschemav2test/v2_test.go

@@ -28,6 +28,7 @@ import (
 	"github.com/pingcap/tidb/pkg/domain/infosync"
 	"github.com/pingcap/tidb/pkg/infoschema"
 	infoschemacontext "github.com/pingcap/tidb/pkg/infoschema/context"
+	"github.com/pingcap/tidb/pkg/meta/autoid"
 	"github.com/pingcap/tidb/pkg/parser/auth"
 	"github.com/pingcap/tidb/pkg/parser/model"
 	"github.com/pingcap/tidb/pkg/sessionctx/variable"
@@ -534,3 +535,26 @@ func TestSnapshotInfoschemaReader(t *testing.T) {
 	sql = fmt.Sprintf("select * from INFORMATION_SCHEMA.TABLES as of timestamp '%s' where table_schema = 'issue55827'", timeStr)
 	tk.MustQuery(sql).Check(testkit.Rows())
 }
+
+func TestInfoSchemaCachedAutoIncrement(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	autoid.SetStep(1)
+	tk.MustExec("set @@global.tidb_schema_cache_size = 0;")
+	tk.MustExec("create table t (a int primary key auto_increment);")
+	autoIncQuery := "select auto_increment from information_schema.tables where table_name = 't' and table_schema = 'test';"
+
+	tk.MustQuery(autoIncQuery).Check(testkit.Rows("0"))
+	tk.MustExec("insert into t values (),(),();")
+	tk.MustQuery(autoIncQuery).Check(testkit.Rows("4"))
+
+	tk.MustExec("set @@global.tidb_schema_cache_size = 1024 * 1024 * 1024;")
+	tk.MustExec("create table t1 (a int);") // trigger infoschema cache reload
+	tk.MustQuery(autoIncQuery).Check(testkit.Rows("0"))
+	tk.MustExec("insert into t values ();")
+	tk.MustQuery(autoIncQuery).Check(testkit.Rows("5"))
+	tk.MustExec("set @@global.tidb_schema_cache_size = 0;")
+	tk.MustExec("drop table t1;") // trigger infoschema cache reload
+	tk.MustQuery(autoIncQuery).Check(testkit.Rows("0"))
+}

pkg/statistics/handle/cache/stats_table_row_cache.go

@@ -239,28 +239,27 @@ func getColLengthTables(sctx sessionctx.Context, tableIDs ...int64) (map[tableHi
 
 // GetDataAndIndexLength gets the data and index length of the table.
 func (c *StatsTableRowCache) GetDataAndIndexLength(info *model.TableInfo, physicalID int64, rowCount uint64) (dataLength, indexLength uint64) {
-	columnLength := make(map[string]uint64, len(info.Columns))
-	for _, col := range info.Columns {
+	columnLength := make([]uint64, len(info.Columns))
+	for i, col := range info.Columns {
 		if col.State != model.StatePublic {
 			continue
 		}
-		length := col.FieldType.StorageLength()
-		if length != types.VarStorageLen {
-			columnLength[col.Name.L] = rowCount * uint64(length)
+		var length uint64
+		if storageLen := col.FieldType.StorageLength(); storageLen != types.VarStorageLen {
+			length = rowCount * uint64(storageLen)
 		} else {
-			length := c.GetColLength(tableHistID{tableID: physicalID, histID: col.ID})
-			columnLength[col.Name.L] = length
+			length = c.GetColLength(tableHistID{tableID: physicalID, histID: col.ID})
 		}
-	}
-	for _, length := range columnLength {
 		dataLength += length
+		columnLength[i] = length
 	}
+
 	for _, idx := range info.Indices {
 		if idx.State != model.StatePublic {
 			continue
 		}
 		if info.GetPartitionInfo() != nil {
-			// Global indexes calcuated in table level.
+			// Global indexes calculated in table level.
 			if idx.Global && info.ID != physicalID {
 				continue
 			}
@@ -271,7 +270,7 @@ func (c *StatsTableRowCache) GetDataAndIndexLength(info *model.TableInfo, physic
 		}
 		for _, col := range idx.Columns {
 			if col.Length == types.UnspecifiedLength {
-				indexLength += columnLength[col.Name.L]
+				indexLength += columnLength[col.Offset]
 			} else {
 				indexLength += rowCount * uint64(col.Length)
 			}