planner: fix panic during starting tidb-server if creating global bin…

…ding for partition table (#40402)

* fix

Co-authored-by: Ti Chi Robot <[email protected]>

executor/analyzetest/analyze_test.go

@@ -2833,7 +2833,7 @@ PARTITION BY RANGE ( a ) (
 	tk.MustQuery("select * from t where a > 1 and b > 1 and c > 1 and d > 1")
 	require.NoError(t, h.LoadNeededHistograms())
 	tbl := h.GetTableStats(tableInfo)
-	require.Equal(t, 4, len(tbl.Columns))
+	require.Equal(t, 0, len(tbl.Columns))
 
 	// ignore both p0's 3 buckets, persisted-partition-options' 1 bucket, just use table-level 2 buckets
 	tk.MustExec("analyze table t partition p0")

planner/core/collect_column_stats_usage_test.go

@@ -331,6 +331,11 @@ func TestCollectHistNeededColumns(t *testing.T) {
 		if len(tt.pruneMode) > 0 {
 			s.ctx.GetSessionVars().PartitionPruneMode.Store(tt.pruneMode)
 		}
+		if s.ctx.GetSessionVars().IsDynamicPartitionPruneEnabled() {
+			s.ctx.GetSessionVars().StmtCtx.UseDynamicPruneMode = true
+		} else {
+			s.ctx.GetSessionVars().StmtCtx.UseDynamicPruneMode = false
+		}
 		stmt, err := s.p.ParseOneStmt(tt.sql, "", "")
 		require.NoError(t, err, comment)
 		err = Preprocess(context.Background(), s.ctx, stmt, WithPreprocessorReturn(&PreprocessorReturn{InfoSchema: s.is}))

planner/core/integration_partition_test.go

@@ -1619,3 +1619,39 @@ func TestPartitionRangeColumnPruning(t *testing.T) {
 	tk.MustQuery(`select * from t1 where a = 'a' AND c = 'd'`).Check(testkit.Rows("a <nil> d"))
 	tk.MustExec(`drop table t1`)
 }
+
+func TestPartitionProcessorWithUninitializedTable(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec(" create table q1(a int, b int, key (a)) partition by range (a) (partition p0 values less than (10), partition p1 values less than (20));")
+	tk.MustExec(" create table q2(a int, b int, key (a)) partition by range (a) (partition p0 values less than (10), partition p1 values less than (20));")
+
+	rows := [][]interface{}{
+		{"HashJoin"},
+		{"├─PartitionUnion(Build)"},
+		{"│ ├─TableReader"},
+		{"│ │ └─TableFullScan"},
+		{"│ └─TableReader"},
+		{"│   └─TableFullScan"},
+		{"└─PartitionUnion(Probe)"},
+		{"  ├─TableReader"},
+		{"  │ └─TableFullScan"},
+		{"  └─TableReader"},
+		{"    └─TableFullScan"},
+	}
+	tk.MustQuery("explain format=brief select * from q1,q2").CheckAt([]int{0}, rows)
+
+	tk.MustExec("analyze table q1")
+	tk.MustQuery("explain format=brief select * from q1,q2").CheckAt([]int{0}, rows)
+
+	tk.MustExec("analyze table q2")
+	rows = [][]interface{}{
+		{"HashJoin"},
+		{"├─TableReader(Build)"},
+		{"│ └─TableFullScan"},
+		{"└─TableReader(Probe)"},
+		{"  └─TableFullScan"},
+	}
+	tk.MustQuery("explain format=brief select * from q1,q2").CheckAt([]int{0}, rows)
+}

planner/core/logical_plan_builder.go

@@ -4471,30 +4471,39 @@ func (b *PlanBuilder) buildDataSource(ctx context.Context, tn *ast.TableName, as
 	}
 
 	if tableInfo.GetPartitionInfo() != nil {
-		h := domain.GetDomain(b.ctx).StatsHandle()
-		tblStats := h.GetTableStats(tableInfo)
-		isDynamicEnabled := b.ctx.GetSessionVars().IsDynamicPartitionPruneEnabled()
-		globalStatsReady := tblStats.IsInitialized()
-		// If dynamic partition prune isn't enabled or global stats is not ready, we won't enable dynamic prune mode in query
-		usePartitionProcessor := !isDynamicEnabled || !globalStatsReady
-
-		failpoint.Inject("forceDynamicPrune", func(val failpoint.Value) {
-			if val.(bool) {
-				if isDynamicEnabled {
-					usePartitionProcessor = false
-				}
-			}
-		})
-
-		if usePartitionProcessor {
+		// If `UseDynamicPruneMode` already been false, then we don't need to check whether execute `flagPartitionProcessor`
+		// otherwise we need to check global stats initialized for each partition table
+		if !b.ctx.GetSessionVars().IsDynamicPartitionPruneEnabled() {
 			b.optFlag = b.optFlag | flagPartitionProcessor
-			b.ctx.GetSessionVars().StmtCtx.UseDynamicPruneMode = false
-			if isDynamicEnabled {
-				b.ctx.GetSessionVars().StmtCtx.AppendWarning(
-					fmt.Errorf("disable dynamic pruning due to %s has no global stats", tableInfo.Name.String()))
+		} else {
+			if !b.ctx.GetSessionVars().StmtCtx.UseDynamicPruneMode {
+				b.optFlag = b.optFlag | flagPartitionProcessor
+			} else {
+				h := domain.GetDomain(b.ctx).StatsHandle()
+				tblStats := h.GetTableStats(tableInfo)
+				isDynamicEnabled := b.ctx.GetSessionVars().IsDynamicPartitionPruneEnabled()
+				globalStatsReady := tblStats.IsInitialized()
+				// If dynamic partition prune isn't enabled or global stats is not ready, we won't enable dynamic prune mode in query
+				usePartitionProcessor := !isDynamicEnabled || !globalStatsReady
+
+				failpoint.Inject("forceDynamicPrune", func(val failpoint.Value) {
+					if val.(bool) {
+						if isDynamicEnabled {
+							usePartitionProcessor = false
+						}
+					}
+				})
+
+				if usePartitionProcessor {
+					b.optFlag = b.optFlag | flagPartitionProcessor
+					b.ctx.GetSessionVars().StmtCtx.UseDynamicPruneMode = false
+					if isDynamicEnabled {
+						b.ctx.GetSessionVars().StmtCtx.AppendWarning(
+							fmt.Errorf("disable dynamic pruning due to %s has no global stats", tableInfo.Name.String()))
+					}
+				}
 			}
 		}
-
 		pt := tbl.(table.PartitionedTable)
 		// check partition by name.
 		if len(tn.PartitionNames) > 0 {

statistics/handle/handle.go

@@ -973,8 +973,13 @@ func (h *Handle) GetTableStats(tblInfo *model.TableInfo, opts ...TableStatsOpt)
 
 // GetPartitionStats retrieves the partition stats from cache.
 func (h *Handle) GetPartitionStats(tblInfo *model.TableInfo, pid int64, opts ...TableStatsOpt) *statistics.Table {
-	statsCache := h.statsCache.Load().(statsCache)
 	var tbl *statistics.Table
+	if h == nil {
+		tbl = statistics.PseudoTable(tblInfo)
+		tbl.PhysicalID = pid
+		return tbl
+	}
+	statsCache := h.statsCache.Load().(statsCache)
 	var ok bool
 	option := &tableStatsOption{}
 	for _, opt := range opts {