statistics: right deal with error for reading stats from storage

pkg/executor/test/tiflashtest/tiflash_test.go

@@ -1020,7 +1020,7 @@ func TestIssue57149(t *testing.T) {
 }
 
 func TestTiFlashPartitionTableBroadcastJoin(t *testing.T) {
-	store := testkit.CreateMockStore(t, withMockTiFlash(2))
+	store, dom := testkit.CreateMockStoreAndDomain(t, withMockTiFlash(2))
 	tk := testkit.NewTestKit(t, store)
 	tk.MustExec("create database tiflash_partition_BCJ")
 	tk.MustExec("use tiflash_partition_BCJ")
@@ -1040,7 +1040,8 @@ func TestTiFlashPartitionTableBroadcastJoin(t *testing.T) {
 		partition p0 values in (` + listPartitions[0] + `), partition p1 values in (` + listPartitions[1] + `),
 		partition p2 values in (` + listPartitions[2] + `), partition p3 values in (` + listPartitions[3] + `))`)
 	tk.MustExec(`create table tnormal (a int, b int) partition by hash(a) partitions 4`)
-
+	h := dom.StatsHandle()
+	require.NoError(t, h.HandleDDLEvent(<-h.DDLEventCh()))
 	for _, tbl := range []string{`thash`, `trange`, `tlist`, `tnormal`} {
 		tk.MustExec("alter table " + tbl + " set tiflash replica 1")
 		tb := external.GetTableByName(t, tk, "tiflash_partition_BCJ", tbl)
@@ -1054,7 +1055,7 @@ func TestTiFlashPartitionTableBroadcastJoin(t *testing.T) {
 	}
 	for _, tbl := range []string{`thash`, `trange`, `tlist`, `tnormal`} {
 		tk.MustExec(fmt.Sprintf("insert into %v values %v", tbl, strings.Join(vals, ", ")))
-		tk.MustExec(fmt.Sprintf("analyze table %v", tbl))
+		tk.MustExec(fmt.Sprintf("analyze table %v all columns", tbl))
 	}
 	tk.MustExec("set @@session.tidb_isolation_read_engines='tiflash'")
 	tk.MustExec("set @@session.tidb_enforce_mpp=1")

pkg/statistics/handle/globalstats/global_stats_async.go

@@ -517,7 +517,9 @@ func (a *AsyncMergePartitionStats2GlobalStats) dealHistogramAndTopN(stmtCtx *stm
 			if err != nil {
 				return err
 			}
-
+			if len(allhg) == 0 && len(poppedTopN) == 0 {
+				return errors.New("empty hg cannot merge")
+			}
 			// Merge histogram.
 			globalHg := &(a.globalStats.Hg[item.idx])
 			*globalHg, err = statistics.MergePartitionHist2GlobalHist(stmtCtx, allhg, poppedTopN,

pkg/statistics/handle/handletest/BUILD.bazel

@@ -9,13 +9,14 @@ go_test(
     ],
     flaky = True,
     race = "on",
-    shard_count = 33,
+    shard_count = 34,
     deps = [
         "//pkg/config",
         "//pkg/domain",
         "//pkg/parser/model",
         "//pkg/planner/cardinality",
         "//pkg/sessionctx/variable",
+        "//pkg/sessiontxn",
         "//pkg/statistics",
         "//pkg/statistics/handle",
         "//pkg/statistics/handle/util",

pkg/statistics/handle/handletest/handle_test.go

@@ -28,6 +28,7 @@ import (
 	"github.com/pingcap/tidb/pkg/parser/model"
 	"github.com/pingcap/tidb/pkg/planner/cardinality"
 	"github.com/pingcap/tidb/pkg/sessionctx/variable"
+	"github.com/pingcap/tidb/pkg/sessiontxn"
 	"github.com/pingcap/tidb/pkg/statistics"
 	"github.com/pingcap/tidb/pkg/statistics/handle"
 	"github.com/pingcap/tidb/pkg/statistics/handle/util"
@@ -1489,3 +1490,23 @@ func TestSkipMissingPartitionStats(t *testing.T) {
 		return false
 	})
 }
+
+func TestReadStatsWithoutAnalyzeAndHandleEvent(t *testing.T) {
+	// it means it only has stats_meta without stats_hist
+	store, dom := testkit.CreateMockStoreAndDomain(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("set @@tidb_partition_prune_mode = 'dynamic'")
+	tk.MustExec("set @@tidb_skip_missing_partition_stats = 1")
+	tk.MustExec("create table t (a int, b int, c int, index idx_b(b)) partition by range (a) (partition p0 values less than (100), partition p1 values less than (200), partition p2 values less than (300))")
+	tk.MustExec("insert into t values (1,1,1), (2,2,2), (101,101,101), (102,102,102), (201,201,201), (202,202,202)")
+	h := dom.StatsHandle()
+	require.NoError(t, h.DumpStatsDeltaToKV(true))
+	is := sessiontxn.GetTxnManager(tk.Session()).GetTxnInfoSchema()
+	table, err := is.TableByName(context.Background(), model.NewCIStr("test"), model.NewCIStr("t"))
+	require.NoError(t, err)
+	tableInfo := table.Meta()
+	tblStats, err := h.TableStatsFromStorage(tableInfo, tableInfo.ID, true, 0)
+	require.NoError(t, err)
+	require.NotNil(t, tblStats)
+}

pkg/statistics/handle/storage/read.go

@@ -539,9 +539,13 @@ func TableStatsFromStorage(sctx sessionctx.Context, snapshot uint64, tableInfo *
 	table.RealtimeCount = realtimeCount
 
 	rows, _, err := util.ExecRows(sctx, "select table_id, is_index, hist_id, distinct_count, version, null_count, tot_col_size, stats_ver, flag, correlation, last_analyze_pos from mysql.stats_histograms where table_id = %?", tableID)
+	if err != nil {
+		return nil, err
+	}
 	// Check deleted table.
-	if err != nil || len(rows) == 0 {
-		return nil, nil
+	if len(rows) == 0 {
+		table.Pseudo = true
+		return table, nil
 	}
 	for _, row := range rows {
 		if err := sctx.GetSessionVars().SQLKiller.HandleSignal(); err != nil {