planner: do not choose point get when exists read from tiflash hint.

planner/core/find_best_task.go

@@ -491,7 +491,7 @@ func (ds *DataSource) findBestTask(prop *property.PhysicalProperty) (t task, err
 
 	for _, candidate := range candidates {
 		path := candidate.path
-		if path.PartialIndexPaths != nil {
+		if path.PartialIndexPaths != nil && ds.preferStoreType&preferTiFlash == 0 {
 			idxMergeTask, err := ds.convertToIndexMergeScan(prop, candidate)
 			if err != nil {
 				return nil, err
@@ -510,7 +510,7 @@ func (ds *DataSource) findBestTask(prop *property.PhysicalProperty) (t task, err
 			}, nil
 		}
 		canConvertPointGet := (!ds.isPartition && len(path.Ranges) > 0) || (ds.isPartition && len(path.Ranges) == 1)
-		canConvertPointGet = canConvertPointGet && candidate.path.StoreType != kv.TiFlash
+		canConvertPointGet = canConvertPointGet && candidate.path.StoreType != kv.TiFlash && ds.preferStoreType&preferTiFlash == 0
 		if !candidate.path.IsTablePath {
 			canConvertPointGet = canConvertPointGet &&
 				candidate.path.Index.Unique &&

planner/core/integration_test.go

@@ -494,6 +494,41 @@ func (s *testIntegrationSerialSuite) TestIsolationReadTiFlashNotChoosePointGet(c
 	}
 }
 
+func (s *testIntegrationSerialSuite) TestHintReadTiFlashNotChoosePointGet(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t(a int, b int, primary key (a))")
+	tk.MustExec("insert into t values(1,1), (2,2)")
+
+	// Create virtual tiflash replica info.
+	dom := domain.GetDomain(tk.Se)
+	is := dom.InfoSchema()
+	db, exists := is.SchemaByName(model.NewCIStr("test"))
+	c.Assert(exists, IsTrue)
+	for _, tblInfo := range db.Tables {
+		tblInfo.TiFlashReplica = &model.TiFlashReplicaInfo{
+			Count:     1,
+			Available: true,
+		}
+	}
+
+	var input []string
+	var output []struct {
+		SQL    string
+		Result []string
+	}
+	s.testData.GetTestCases(c, &input, &output)
+	for i, tt := range input {
+		s.testData.OnRecord(func() {
+			output[i].SQL = tt
+			output[i].Result = s.testData.ConvertRowsToStrings(tk.MustQuery(tt).Rows())
+		})
+		tk.MustQuery(tt).Check(testkit.Rows(output[i].Result...))
+	}
+}
+
 func (s *testIntegrationSerialSuite) TestIsolationReadTiFlashUseIndexHint(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 

planner/core/point_get_plan.go

@@ -541,7 +541,23 @@ func newBatchPointGetPlan(
 	}.Init(ctx, statsInfo, schema, names, 0)
 }
 
+func isHintReadFromTiFlash(hint *ast.TableOptimizerHint) bool {
+	return hint.HintName.L == "read_from_storage" && hint.HintData.(model.CIStr).L == "tiflash"
+}
+
+func selStmtHasTiFlashHint(selStmt *ast.SelectStmt) bool {
+	for _, hint := range selStmt.TableHints {
+		if isHintReadFromTiFlash(hint) {
+			return true
+		}
+	}
+	return false
+}
+
 func tryWhereIn2BatchPointGet(ctx sessionctx.Context, selStmt *ast.SelectStmt) *BatchPointGetPlan {
+	if selStmtHasTiFlashHint(selStmt) {
+		return nil
+	}
 	if selStmt.OrderBy != nil || selStmt.GroupBy != nil ||
 		selStmt.Limit != nil || selStmt.Having != nil ||
 		len(selStmt.WindowSpecs) > 0 {
@@ -636,6 +652,9 @@ func tryWhereIn2BatchPointGet(ctx sessionctx.Context, selStmt *ast.SelectStmt) *
 // 3. All the columns must be public and generated.
 // 4. The condition is an access path that the range is a unique key.
 func tryPointGetPlan(ctx sessionctx.Context, selStmt *ast.SelectStmt) *PointGetPlan {
+	if selStmtHasTiFlashHint(selStmt) {
+		return nil
+	}
 	if selStmt.Having != nil {
 		return nil
 	} else if selStmt.Limit != nil {

planner/core/stats.go

@@ -20,6 +20,7 @@ import (
 	"github.com/pingcap/parser/ast"
 	"github.com/pingcap/parser/mysql"
 	"github.com/pingcap/tidb/expression"
+	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/planner/property"
 	"github.com/pingcap/tidb/planner/util"
 	"github.com/pingcap/tidb/statistics"
@@ -182,8 +183,12 @@ func (ds *DataSource) DeriveStats(childStats []*property.StatsInfo, selfSchema *
 	for i, expr := range ds.pushedDownConds {
 		ds.pushedDownConds[i] = expression.PushDownNot(ds.ctx, expr)
 	}
+	var tiflashPath *util.AccessPath
 	for _, path := range ds.possibleAccessPaths {
 		if path.IsTablePath {
+			if path.StoreType == kv.TiFlash {
+				tiflashPath = path
+			}
 			continue
 		}
 		err := ds.fillIndexPath(path, ds.pushedDownConds)
@@ -192,16 +197,28 @@ func (ds *DataSource) DeriveStats(childStats []*property.StatsInfo, selfSchema *
 		}
 	}
 	ds.stats = ds.deriveStatsByFilter(ds.pushedDownConds, ds.possibleAccessPaths)
+	if tiflashPath != nil {
+		_, err := ds.deriveTablePathStats(tiflashPath, ds.pushedDownConds, false)
+		if err != nil {
+			return nil, err
+		}
+	}
 	for _, path := range ds.possibleAccessPaths {
+		if path.StoreType == kv.TiFlash {
+			continue
+		}
 		if path.IsTablePath {
 			noIntervalRanges, err := ds.deriveTablePathStats(path, ds.pushedDownConds, false)
 			if err != nil {
 				return nil, err
 			}
 			// If we have point or empty range, just remove other possible paths.
-			if noIntervalRanges || len(path.Ranges) == 0 {
+			if (noIntervalRanges || len(path.Ranges) == 0) && path.StoreType == kv.TiKV {
 				ds.possibleAccessPaths[0] = path
 				ds.possibleAccessPaths = ds.possibleAccessPaths[:1]
+				if tiflashPath != nil {
+					ds.possibleAccessPaths = append(ds.possibleAccessPaths, tiflashPath)
+				}
 				break
 			}
 			continue
@@ -211,6 +228,9 @@ func (ds *DataSource) DeriveStats(childStats []*property.StatsInfo, selfSchema *
 		if (noIntervalRanges && path.Index.Unique) || len(path.Ranges) == 0 {
 			ds.possibleAccessPaths[0] = path
 			ds.possibleAccessPaths = ds.possibleAccessPaths[:1]
+			if tiflashPath != nil {
+				ds.possibleAccessPaths = append(ds.possibleAccessPaths, tiflashPath)
+			}
 			break
 		}
 	}

planner/core/testdata/integration_serial_suite_in.json

@@ -40,6 +40,14 @@
       "explain select * from t where t.a in (1, 2)"
     ]
   },
+  {
+    "name": "TestHintReadTiFlashNotChoosePointGet",
+    "cases": [
+      "explain select /*+ read_from_storage(tiflash[t]) */ * from t where t.a = 1",
+      "explain select /*+ read_from_storage(tiflash[t]) */ * from t where t.a in (1, 2, 3)",
+      "explain select /*+ read_from_storage(tikv[t]) */ * from t where t.a = 1"
+    ]
+  },
   {
     "name": "TestIsolationReadTiFlashUseIndexHint",
     "cases": [

planner/core/testdata/integration_serial_suite_out.json

@@ -220,6 +220,31 @@
       }
     ]
   },
+  {
+    "Name": "TestHintReadTiFlashNotChoosePointGet",
+    "Cases": [
+      {
+        "SQL": "explain select /*+ read_from_storage(tiflash[t]) */ * from t where t.a = 1",
+        "Result": [
+          "TableReader_6 1.00 root  data:TableRangeScan_5",
+          "└─TableRangeScan_5 1.00 cop[tiflash] table:t range:[1,1], keep order:false, stats:pseudo"
+        ]
+      },
+      {
+        "SQL": "explain select /*+ read_from_storage(tiflash[t]) */ * from t where t.a in (1, 2, 3)",
+        "Result": [
+          "TableReader_6 3.00 root  data:TableRangeScan_5",
+          "└─TableRangeScan_5 3.00 cop[tiflash] table:t range:[1,1], [2,2], [3,3], keep order:false, stats:pseudo"
+        ]
+      },
+      {
+        "SQL": "explain select /*+ read_from_storage(tikv[t]) */ * from t where t.a = 1",
+        "Result": [
+          "Point_Get_1 1.00 root table:t handle:1"
+        ]
+      }
+    ]
+  },
   {
     "Name": "TestIsolationReadTiFlashUseIndexHint",
     "Cases": [