planner: remove the unnecessary skip-plan-cache flag in StmtCtx

expression/builtin_compare.go

@@ -1586,7 +1586,7 @@ func (c *compareFunctionClass) refineArgs(ctx sessionctx.Context, args []Express
  } else {
  return args
  }
- } else if ctx.GetSessionVars().StmtCtx.SkipPlanCache {
+ } else if !ctx.GetSessionVars().StmtCtx.UseCache {
  // We should remove the mutable constant for correctness, because its value may be changed.
  RemoveMutableConst(ctx, args)
  }

expression/util.go

@@ -1241,7 +1241,7 @@ 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 || ctx.GetSessionVars().StmtCtx.SkipPlanCache {
+ if !ctx.GetSessionVars().StmtCtx.UseCache {
  return false
  }
  return containMutableConst(ctx, exprs)

planner/core/expression_rewriter.go

@@ -1567,7 +1567,7 @@ func (er *expressionRewriter) inToExpression(lLen int, not bool, tp *types.Field
  } else {
  continue
  }
- } else if er.sctx.GetSessionVars().StmtCtx.SkipPlanCache {
+ } else if !er.sctx.GetSessionVars().StmtCtx.UseCache {
  // We should remove the mutable constant for correctness, because its value may be changed.
  expression.RemoveMutableConst(er.sctx, []expression.Expression{c})
  }

planner/core/plan_cache.go

@@ -280,7 +280,7 @@ func generateNewPlan(ctx context.Context, sctx sessionctx.Context, isNonPrepared
  if containTableDual(p) && paramNum > 0 {
  stmtCtx.SetSkipPlanCache(errors.New("skip plan-cache: get a TableDual plan"))
  }
- if stmtAst.UseCache && !stmtCtx.SkipPlanCache && !ignorePlanCache {
+ if stmtCtx.UseCache && !ignorePlanCache {
  // rebuild key to exclude kv.TiFlash when stmt is not read only
  if _, isolationReadContainTiFlash := sessVars.IsolationReadEngines[kv.TiFlash]; isolationReadContainTiFlash && !IsReadOnly(stmtAst.Stmt, sessVars) {
  delete(sessVars.IsolationReadEngines, kv.TiFlash)
@@ -640,7 +640,7 @@ func CheckPreparedPriv(sctx sessionctx.Context, stmt *PlanCacheStmt, is infosche
 // short paths for these executions, currently "point select" and "point update"
 func tryCachePointPlan(_ context.Context, sctx sessionctx.Context,
  stmt *PlanCacheStmt, _ infoschema.InfoSchema, p Plan) error {
- if !sctx.GetSessionVars().StmtCtx.UseCache || sctx.GetSessionVars().StmtCtx.SkipPlanCache {
+ if !sctx.GetSessionVars().StmtCtx.UseCache {
  return nil
  }
  var (

sessionctx/stmtctx/stmtctx.go

@@ -172,7 +172,6 @@ type StatementContext struct {
  InNullRejectCheck bool
  AllowInvalidDate bool
  IgnoreNoPartition bool
- SkipPlanCache bool
  IgnoreExplainIDSuffix bool
  SkipUTF8Check bool
  SkipASCIICheck bool
@@ -611,10 +610,10 @@ func (sc *StatementContext) SetPlanHint(hint string) {
 
 // SetSkipPlanCache sets to skip the plan cache and records the reason.
 func (sc *StatementContext) SetSkipPlanCache(reason error) {
- if sc.UseCache && sc.SkipPlanCache {
+ if !sc.UseCache {
  return // avoid unnecessary warnings
  }
- sc.SkipPlanCache = true
+ sc.UseCache = false
  sc.AppendWarning(reason)
 }