Function optimize

pkg/planner/optimize.go:472–545

(ctx context.Context, sctx planctx.PlanContext, node *resolve.NodeW, is infoschema.InfoSchema)

var optimizeCnt int

func optimize(ctx context.Context, sctx planctx.PlanContext, node *resolve.NodeW, is infoschema.InfoSchema) (base.Plan, types.NameSlice, float64, error) {
	failpoint.Inject("checkOptimizeCountOne", func(val failpoint.Value) {
		// only count the optimization for SQL with specified text
		if testSQL, ok := val.(string); ok && testSQL == node.Node.OriginalText() {
			optimizeCnt++
			if optimizeCnt > 1 {
				failpoint.Return(nil, nil, 0, errors.New("gofail wrong optimizerCnt error"))
			}
		}
	})
	failpoint.Inject("mockHighLoadForOptimize", func() {
		sqlPrefixes := []string{"select"}
		topsql.MockHighCPULoad(sctx.GetSessionVars().StmtCtx.OriginalSQL, sqlPrefixes, 10)
	})
	sessVars := sctx.GetSessionVars()
	if sessVars.StmtCtx.EnableOptimizerDebugTrace {
		debugtrace.EnterContextCommon(sctx)
		defer debugtrace.LeaveContextCommon(sctx)
	}

	// build logical plan
	hintProcessor := hint.NewQBHintHandler(sctx.GetSessionVars().StmtCtx)
	node.Node.Accept(hintProcessor)
	defer hintProcessor.HandleUnusedViewHints()
	builder := planBuilderPool.Get().(*core.PlanBuilder)
	defer planBuilderPool.Put(builder.ResetForReuse())
	builder.Init(sctx, is, hintProcessor)
	p, err := buildLogicalPlan(ctx, sctx, node, builder)
	if err != nil {
		return nil, nil, 0, err
	}

	activeRoles := sessVars.ActiveRoles
	// Check privilege. Maybe it's better to move this to the Preprocess, but
	// we need the table information to check privilege, which is collected
	// into the visitInfo in the logical plan builder.
	if pm := privilege.GetPrivilegeManager(sctx); pm != nil {
		visitInfo := core.VisitInfo4PrivCheck(ctx, is, node.Node, builder.GetVisitInfo())
		if err := core.CheckPrivilege(activeRoles, pm, visitInfo); err != nil {
			return nil, nil, 0, err
		}
	}

	if err := core.CheckTableLock(sctx, is, builder.GetVisitInfo()); err != nil {
		return nil, nil, 0, err
	}

	if err := core.CheckTableMode(node); err != nil {
		return nil, nil, 0, err
	}

	names := p.OutputNames()

	// Handle the non-logical plan statement.
	logic, isLogicalPlan := p.(base.LogicalPlan)
	if !isLogicalPlan {
		return p, names, 0, nil
	}