planner: store the hints of session variable (#45814) (#46046)

close #45812

Author: ti-chi-bot

planner/core/plan_cache.go

@@ -209,6 +209,9 @@ func getPointQueryPlan(stmt *ast.Prepared, sessVars *variable.SessionVars, stmtC
 	}
 	sessVars.FoundInPlanCache = true
 	stmtCtx.PointExec = true
+	if pointGetPlan, ok := plan.(*PointGetPlan); ok && pointGetPlan != nil && pointGetPlan.stmtHints != nil {
+		sessVars.StmtCtx.StmtHints = *pointGetPlan.stmtHints
+	}
 	return plan, names, true, nil
 }
 
@@ -251,6 +254,7 @@ func getGeneralPlan(sctx sessionctx.Context, isGeneralPlanCache bool, cacheKey k
 		planCacheCounter.Inc()
 	}
 	stmtCtx.SetPlanDigest(stmt.NormalizedPlan, stmt.PlanDigest)
+	stmtCtx.StmtHints = *cachedVal.stmtHints
 	return cachedVal.Plan, cachedVal.OutPutNames, true, nil
 }
 
@@ -289,7 +293,7 @@ func generateNewPlan(ctx context.Context, sctx sessionctx.Context, isGeneralPlan
 			}
 			sessVars.IsolationReadEngines[kv.TiFlash] = struct{}{}
 		}
-		cached := NewPlanCacheValue(p, names, stmtCtx.TblInfo2UnionScan, paramTypes)
+		cached := NewPlanCacheValue(p, names, stmtCtx.TblInfo2UnionScan, paramTypes, &stmtCtx.StmtHints)
 		stmt.NormalizedPlan, stmt.PlanDigest = NormalizePlan(p)
 		stmtCtx.SetPlan(p)
 		stmtCtx.SetPlanDigest(stmt.NormalizedPlan, stmt.PlanDigest)
@@ -687,12 +691,15 @@ func tryCachePointPlan(_ context.Context, sctx sessionctx.Context,
 		names   types.NameSlice
 	)
 
-	if _, _ok := p.(*PointGetPlan); _ok {
+	if plan, _ok := p.(*PointGetPlan); _ok {
 		ok, err = IsPointGetWithPKOrUniqueKeyByAutoCommit(sctx, p)
 		names = p.OutputNames()
 		if err != nil {
 			return err
 		}
+		if ok {
+			plan.stmtHints = sctx.GetSessionVars().StmtCtx.StmtHints.Clone()
+		}
 	}
 
 	if ok {

planner/core/plan_cache_utils.go

@@ -28,6 +28,7 @@ import (
 	"github.com/pingcap/tidb/parser/model"
 	"github.com/pingcap/tidb/parser/mysql"
 	"github.com/pingcap/tidb/sessionctx"
+	"github.com/pingcap/tidb/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/types"
 	driver "github.com/pingcap/tidb/types/parser_driver"
@@ -348,6 +349,8 @@ type PlanCacheValue struct {
 	TblInfo2UnionScan map[*model.TableInfo]bool
 	ParamTypes        FieldSlice
 	memoryUsage       int64
+	// stmtHints stores the hints which set session variables, because the hints won't be processed using cached plan.
+	stmtHints *stmtctx.StmtHints
 }
 
 func (v *PlanCacheValue) varTypesUnchanged(txtVarTps []*types.FieldType) bool {
@@ -395,7 +398,7 @@ func (v *PlanCacheValue) MemoryUsage() (sum int64) {
 
 // NewPlanCacheValue creates a SQLCacheValue.
 func NewPlanCacheValue(plan Plan, names []*types.FieldName, srcMap map[*model.TableInfo]bool,
-	paramTypes []*types.FieldType) *PlanCacheValue {
+	paramTypes []*types.FieldType, stmtHints *stmtctx.StmtHints) *PlanCacheValue {
 	dstMap := make(map[*model.TableInfo]bool)
 	for k, v := range srcMap {
 		dstMap[k] = v
@@ -409,6 +412,7 @@ func NewPlanCacheValue(plan Plan, names []*types.FieldName, srcMap map[*model.Ta
 		OutPutNames:       names,
 		TblInfo2UnionScan: dstMap,
 		ParamTypes:        userParamTypes,
+		stmtHints:         stmtHints.Clone(),
 	}
 }
 

planner/core/point_get_plan.go

@@ -96,6 +96,8 @@ type PointGetPlan struct {
 	// probeParents records the IndexJoins and Applys with this operator in their inner children.
 	// Please see comments in PhysicalPlan for details.
 	probeParents []PhysicalPlan
+	// stmtHints should restore in executing context.
+	stmtHints *stmtctx.StmtHints
 }
 
 func (p *PointGetPlan) getEstRowCountForDisplay() float64 {

session/session_test/BUILD.bazel

@@ -26,6 +26,7 @@ go_test(
         "//privilege/privileges",
         "//session",
         "//sessionctx",
+        "//sessionctx/stmtctx",
         "//sessionctx/variable",
         "//store/copr",
         "//store/mockstore",

session/session_test/session_test.go

@@ -42,6 +42,7 @@ import (
 	"github.com/pingcap/tidb/privilege/privileges"
 	"github.com/pingcap/tidb/session"
 	"github.com/pingcap/tidb/sessionctx"
+	"github.com/pingcap/tidb/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/store/copr"
 	"github.com/pingcap/tidb/store/mockstore"
@@ -4139,3 +4140,63 @@ func TestSQLModeOp(t *testing.T) {
 	a = mysql.SetSQLMode(s, mysql.ModeAllowInvalidDates)
 	require.Equal(t, mysql.ModeNoBackslashEscapes|mysql.ModeOnlyFullGroupBy|mysql.ModeAllowInvalidDates, a)
 }
+
+func TestPrepareExecuteWithSQLHints(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	se := tk.Session()
+	se.SetConnectionID(1)
+	tk.MustExec("use test")
+	tk.MustExec("create table t(a int primary key)")
+
+	type hintCheck struct {
+		hint  string
+		check func(*stmtctx.StmtHints)
+	}
+
+	hintChecks := []hintCheck{
+		{
+			hint: "MEMORY_QUOTA(1024 MB)",
+			check: func(stmtHint *stmtctx.StmtHints) {
+				require.True(t, stmtHint.HasMemQuotaHint)
+				require.Equal(t, int64(1024*1024*1024), stmtHint.MemQuotaQuery)
+			},
+		},
+		{
+			hint: "READ_CONSISTENT_REPLICA()",
+			check: func(stmtHint *stmtctx.StmtHints) {
+				require.True(t, stmtHint.HasReplicaReadHint)
+				require.Equal(t, byte(kv.ReplicaReadFollower), stmtHint.ReplicaRead)
+			},
+		},
+		{
+			hint: "MAX_EXECUTION_TIME(1000)",
+			check: func(stmtHint *stmtctx.StmtHints) {
+				require.True(t, stmtHint.HasMaxExecutionTime)
+				require.Equal(t, uint64(1000), stmtHint.MaxExecutionTime)
+			},
+		},
+		{
+			hint: "USE_TOJA(TRUE)",
+			check: func(stmtHint *stmtctx.StmtHints) {
+				require.True(t, stmtHint.HasAllowInSubqToJoinAndAggHint)
+				require.True(t, stmtHint.AllowInSubqToJoinAndAgg)
+			},
+		},
+	}
+
+	for i, check := range hintChecks {
+		// common path
+		tk.MustExec(fmt.Sprintf("prepare stmt%d from 'select /*+ %s */ * from t'", i, check.hint))
+		for j := 0; j < 10; j++ {
+			tk.MustQuery(fmt.Sprintf("execute stmt%d", i))
+			check.check(&tk.Session().GetSessionVars().StmtCtx.StmtHints)
+		}
+		// fast path
+		tk.MustExec(fmt.Sprintf("prepare fast%d from 'select /*+ %s */ * from t where a = 1'", i, check.hint))
+		for j := 0; j < 10; j++ {
+			tk.MustQuery(fmt.Sprintf("execute fast%d", i))
+			check.check(&tk.Session().GetSessionVars().StmtCtx.StmtHints)
+		}
+	}
+}

sessionctx/stmtctx/BUILD.bazel

@@ -34,7 +34,7 @@ go_test(
     ],
     embed = [":stmtctx"],
     flaky = True,
-    shard_count = 5,
+    shard_count = 6,
     deps = [
         "//kv",
         "//sessionctx/variable",

sessionctx/stmtctx/stmtctx.go

@@ -389,7 +389,6 @@ type StatementContext struct {
 type StmtHints struct {
 	// Hint Information
 	MemQuotaQuery           int64
-	ApplyCacheCapacity      int64
 	MaxExecutionTime        uint64
 	ReplicaRead             byte
 	AllowInSubqToJoinAndAgg bool
@@ -418,6 +417,41 @@ func (sh *StmtHints) TaskMapNeedBackUp() bool {
 	return sh.ForceNthPlan != -1
 }
 
+// Clone the StmtHints struct and returns the pointer of the new one.
+func (sh *StmtHints) Clone() *StmtHints {
+	var (
+		vars       map[string]string
+		tableHints []*ast.TableOptimizerHint
+	)
+	if len(sh.SetVars) > 0 {
+		vars = make(map[string]string, len(sh.SetVars))
+		for k, v := range sh.SetVars {
+			vars[k] = v
+		}
+	}
+	if len(sh.OriginalTableHints) > 0 {
+		tableHints = make([]*ast.TableOptimizerHint, len(sh.OriginalTableHints))
+		copy(tableHints, sh.OriginalTableHints)
+	}
+	return &StmtHints{
+		MemQuotaQuery:                  sh.MemQuotaQuery,
+		MaxExecutionTime:               sh.MaxExecutionTime,
+		ReplicaRead:                    sh.ReplicaRead,
+		AllowInSubqToJoinAndAgg:        sh.AllowInSubqToJoinAndAgg,
+		NoIndexMergeHint:               sh.NoIndexMergeHint,
+		StraightJoinOrder:              sh.StraightJoinOrder,
+		EnableCascadesPlanner:          sh.EnableCascadesPlanner,
+		ForceNthPlan:                   sh.ForceNthPlan,
+		HasAllowInSubqToJoinAndAggHint: sh.HasAllowInSubqToJoinAndAggHint,
+		HasMemQuotaHint:                sh.HasMemQuotaHint,
+		HasReplicaReadHint:             sh.HasReplicaReadHint,
+		HasMaxExecutionTime:            sh.HasMaxExecutionTime,
+		HasEnableCascadesPlannerHint:   sh.HasEnableCascadesPlannerHint,
+		SetVars:                        vars,
+		OriginalTableHints:             tableHints,
+	}
+}
+
 // StmtCacheKey represents the key type in the StmtCache.
 type StmtCacheKey int
 

sessionctx/stmtctx/stmtctx_test.go

@@ -19,6 +19,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"math/rand"
+	"reflect"
 	"sort"
 	"testing"
 	"time"
@@ -272,3 +273,25 @@ func TestApproxRuntimeInfo(t *testing.T) {
 		require.Equal(t, d.TotBackoffTime[backoff], timeSum)
 	}
 }
+
+func TestStmtHintsClone(t *testing.T) {
+	hints := stmtctx.StmtHints{}
+	value := reflect.ValueOf(&hints).Elem()
+	for i := 0; i < value.NumField(); i++ {
+		field := value.Field(i)
+		switch field.Kind() {
+		case reflect.Int, reflect.Int32, reflect.Int64:
+			field.SetInt(1)
+		case reflect.Uint, reflect.Uint32, reflect.Uint64:
+			field.SetUint(1)
+		case reflect.Uint8: // byte
+			field.SetUint(1)
+		case reflect.Bool:
+			field.SetBool(true)
+		case reflect.String:
+			field.SetString("test")
+		default:
+		}
+	}
+	require.Equal(t, hints, *hints.Clone())
+}