planner: make clear for MaybeOverOptimized4PlanCache (#29782)

pingcap · Nov 25, 2021 · 8dc59e6 · 8dc59e6
1 parent fe5733c
commit 8dc59e6
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Showing 7 changed files with 36 additions and 35 deletions.
diff --git a/expression/builtin_compare.go b/expression/builtin_compare.go
@@ -1461,11 +1461,14 @@ func (c *compareFunctionClass) refineArgs(ctx sessionctx.Context, args []Express
 		// To keep the result be compatible with MySQL, refine `int non-constant <cmp> str constant`
 		// here and skip this refine operation in all other cases for safety.
 		if (arg0IsInt && !arg0IsCon && arg1IsString && arg1IsCon) || (arg1IsInt && !arg1IsCon && arg0IsString && arg0IsCon) {
-			ctx.GetSessionVars().StmtCtx.MaybeOverOptimized4PlanCache = true
+			ctx.GetSessionVars().StmtCtx.SkipPlanCache = true
 			RemoveMutableConst(ctx, args)
 		} else {
 			return args
 		}
+	} else if ctx.GetSessionVars().StmtCtx.SkipPlanCache {
+		// We should remove the mutable constant for correctness, because its value may be changed.
+		RemoveMutableConst(ctx, args)
 	}
 	// int non-constant [cmp] non-int constant
 	if arg0IsInt && !arg0IsCon && !arg1IsInt && arg1IsCon {

diff --git a/expression/util.go b/expression/util.go
@@ -920,12 +920,7 @@ func ContainCorrelatedColumn(exprs []Expression) bool {
 // TODO: Do more careful check here.
 func MaybeOverOptimized4PlanCache(ctx sessionctx.Context, exprs []Expression) bool {
 	// If we do not enable plan cache, all the optimization can work correctly.
-	if !ctx.GetSessionVars().StmtCtx.UseCache {
-		return false
-	}
-	if ctx.GetSessionVars().StmtCtx.MaybeOverOptimized4PlanCache {
-		// If the current statement can not be cached. We should remove the mutable constant.
-		RemoveMutableConst(ctx, exprs)
+	if !ctx.GetSessionVars().StmtCtx.UseCache || ctx.GetSessionVars().StmtCtx.SkipPlanCache {
 		return false
 	}
 	return containMutableConst(ctx, exprs)

diff --git a/planner/core/common_plans.go b/planner/core/common_plans.go
@@ -496,7 +496,7 @@ REBUILD:
 	e.names = names
 	e.Plan = p
 	_, isTableDual := p.(*PhysicalTableDual)
-	if !isTableDual && prepared.UseCache && !stmtCtx.MaybeOverOptimized4PlanCache {
+	if !isTableDual && prepared.UseCache && !stmtCtx.SkipPlanCache {
 		// rebuild key to exclude kv.TiFlash when stmt is not read only
 		if _, isolationReadContainTiFlash := sessVars.IsolationReadEngines[kv.TiFlash]; isolationReadContainTiFlash && !IsReadOnly(stmt, sessVars) {
 			delete(sessVars.IsolationReadEngines, kv.TiFlash)
@@ -531,7 +531,7 @@ REBUILD:
 // short paths for these executions, currently "point select" and "point update"
 func (e *Execute) tryCachePointPlan(ctx context.Context, sctx sessionctx.Context,
 	preparedStmt *CachedPrepareStmt, is infoschema.InfoSchema, p Plan) error {
-	if sctx.GetSessionVars().StmtCtx.MaybeOverOptimized4PlanCache {
+	if sctx.GetSessionVars().StmtCtx.SkipPlanCache {
 		return nil
 	}
 	var (

diff --git a/planner/core/expression_rewriter.go b/planner/core/expression_rewriter.go
@@ -1454,11 +1454,14 @@ func (er *expressionRewriter) inToExpression(lLen int, not bool, tp *types.Field
 					if c.GetType().EvalType() == types.ETString {
 						// To keep the result be compatible with MySQL, refine `int non-constant <cmp> str constant`
 						// here and skip this refine operation in all other cases for safety.
-						er.sctx.GetSessionVars().StmtCtx.MaybeOverOptimized4PlanCache = true
+						er.sctx.GetSessionVars().StmtCtx.SkipPlanCache = true
 						expression.RemoveMutableConst(er.sctx, []expression.Expression{c})
 					} else {
 						continue
 					}
+				} else if er.sctx.GetSessionVars().StmtCtx.SkipPlanCache {
+					// We should remove the mutable constant for correctness, because its value may be changed.
+					expression.RemoveMutableConst(er.sctx, []expression.Expression{c})
 				}
 				args[i], isExceptional = expression.RefineComparedConstant(er.sctx, *leftFt, c, opcode.EQ)
 				if isExceptional {

diff --git a/planner/core/find_best_task.go b/planner/core/find_best_task.go
@@ -806,7 +806,7 @@ func (ds *DataSource) findBestTask(prop *property.PhysicalProperty, planCounter
 		if len(path.Ranges) == 0 {
 			// We should uncache the tableDual plan.
 			if expression.MaybeOverOptimized4PlanCache(ds.ctx, path.AccessConds) {
-				ds.ctx.GetSessionVars().StmtCtx.MaybeOverOptimized4PlanCache = true
+				ds.ctx.GetSessionVars().StmtCtx.SkipPlanCache = true
 			}
 			dual := PhysicalTableDual{}.Init(ds.ctx, ds.stats, ds.blockOffset)
 			dual.SetSchema(ds.schema)

diff --git a/planner/core/optimizer.go b/planner/core/optimizer.go
@@ -321,7 +321,7 @@ func postOptimize(sctx sessionctx.Context, plan PhysicalPlan) PhysicalPlan {
 // Todo: make more careful check here.
 func checkPlanCacheable(sctx sessionctx.Context, plan PhysicalPlan) {
 	if sctx.GetSessionVars().StmtCtx.UseCache && useTiFlash(plan) {
-		sctx.GetSessionVars().StmtCtx.MaybeOverOptimized4PlanCache = true
+		sctx.GetSessionVars().StmtCtx.SkipPlanCache = true
 	}
 }
 

diff --git a/sessionctx/stmtctx/stmtctx.go b/sessionctx/stmtctx/stmtctx.go
@@ -67,29 +67,29 @@ type StatementContext struct {
 
 	// IsDDLJobInQueue is used to mark whether the DDL job is put into the queue.
 	// If IsDDLJobInQueue is true, it means the DDL job is in the queue of storage, and it can be handled by the DDL worker.
-	IsDDLJobInQueue              bool
-	InInsertStmt                 bool
-	InUpdateStmt                 bool
-	InDeleteStmt                 bool
-	InSelectStmt                 bool
-	InLoadDataStmt               bool
-	InExplainStmt                bool
-	InCreateOrAlterStmt          bool
-	IgnoreTruncate               bool
-	IgnoreZeroInDate             bool
-	DupKeyAsWarning              bool
-	BadNullAsWarning             bool
-	DividedByZeroAsWarning       bool
-	TruncateAsWarning            bool
-	OverflowAsWarning            bool
-	InShowWarning                bool
-	UseCache                     bool
-	BatchCheck                   bool
-	InNullRejectCheck            bool
-	AllowInvalidDate             bool
-	IgnoreNoPartition            bool
-	MaybeOverOptimized4PlanCache bool
-	IgnoreExplainIDSuffix        bool
+	IsDDLJobInQueue        bool
+	InInsertStmt           bool
+	InUpdateStmt           bool
+	InDeleteStmt           bool
+	InSelectStmt           bool
+	InLoadDataStmt         bool
+	InExplainStmt          bool
+	InCreateOrAlterStmt    bool
+	IgnoreTruncate         bool
+	IgnoreZeroInDate       bool
+	DupKeyAsWarning        bool
+	BadNullAsWarning       bool
+	DividedByZeroAsWarning bool
+	TruncateAsWarning      bool
+	OverflowAsWarning      bool
+	InShowWarning          bool
+	UseCache               bool
+	BatchCheck             bool
+	InNullRejectCheck      bool
+	AllowInvalidDate       bool
+	IgnoreNoPartition      bool
+	SkipPlanCache          bool
+	IgnoreExplainIDSuffix  bool
 	// If the select statement was like 'select * from t as of timestamp ...' or in a stale read transaction
 	// or is affected by the tidb_read_staleness session variable, then the statement will be makred as isStaleness
 	// in stmtCtx