C++ ParseTree::walk方法代码示例

 void arithmeticExpression_1()
 {
     cout << "\narithmetic expression: " << endl;
     string exp("substr(a)+ 100.00 * sum(tpch.part.p_type) / sum(tpch.lineitem.l_extendedprice *(1-tpch.lineitem.l_discount))");
     cout << exp << endl;
     ArithmeticColumn a(exp, 0);
     ParseTree* pt = const_cast<ParseTree*>(a.expression());
     if (pt != NULL)
     {
         pt->walk(walkfnString);
         pt->drawTree("arithmeticExpression_1.dot");
     }
     cout << " --- end of test 6 ---" << endl;         
 }

void derivedTableOptimization(SCSEP& csep)
{
	// @bug5634. replace the unused column with ConstantColumn from derived table column list,
	// ExeMgr will not project ConstantColumn. Only count for local derived column.
	// subquery may carry main query derived table list for column reference, those
	// derived tables are not checked for optimization in this scope.
	erydbSelectExecutionPlan::SelectList derivedTbList = csep->derivedTableList();

	// @bug6156. Skip horizontal optimization for no table union.
	bool horizontalOptimization = true;
	for (uint i = 0; i < derivedTbList.size(); i++)
	{
		erydbSelectExecutionPlan *plan = dynamic_cast<erydbSelectExecutionPlan*>(derivedTbList[i].get());
		erydbSelectExecutionPlan::ReturnedColumnList cols = plan->returnedCols();
		vector<erydbSelectExecutionPlan::ReturnedColumnList> unionColVec;

		// only do vertical optimization for union all
		// @bug6134. Also skip the vertical optimization for select distinct
		// because all columns need to be projected to check the distinctness.
		bool verticalOptimization = false;
		if (plan->distinctUnionNum() == 0 && !plan->distinct())
		{
			verticalOptimization = true;
			for (uint j = 0; j < plan->unionVec().size(); j++)
			{
				unionColVec.push_back(
				 dynamic_cast<erydbSelectExecutionPlan*>(plan->unionVec()[j].get())->returnedCols());
			}
		}

		if (plan->tableList().empty())
			horizontalOptimization = false;
		for (uint j = 0; j < plan->unionVec().size(); j++)
		{
			if (dynamic_cast<erydbSelectExecutionPlan*>(plan->unionVec()[j].get())->tableList().empty())
			{
				horizontalOptimization = false;
				break;
			}
		}

		if (verticalOptimization)
		{
			int64_t val = 1;
			for (uint i = 0; i < cols.size(); i++)
			{
				//if (cols[i]->derivedTable().empty())
				if (cols[i]->refCount() == 0)
				{
					if (cols[i]->derivedRefCol())
						cols[i]->derivedRefCol()->decRefCount();
					cols[i].reset(new ConstantColumn(val));
					for (uint j = 0; j < unionColVec.size(); j++)
						unionColVec[j][i].reset(new ConstantColumn(val));
				}
			}

			// set back
			plan->returnedCols(cols);
			for (uint j = 0; j < unionColVec.size(); j++)
				dynamic_cast<erydbSelectExecutionPlan*>(plan->unionVec()[j].get())->returnedCols(unionColVec[j]);
		}
	}

	/*
	 * @bug5635. Move filters that only belongs to a derived table to inside the derived table.
	 * 1. parse tree walk to populate derivedTableFilterMap and set null candidate on the tree.
	 * 2. remove the null filters
	 * 3. and the filters of derivedTableFilterMap and append to the WHERE filter of the derived table
	 *
	 * Note:
	 * 1. Subquery filters is ignored because derived table can not be in subquery
	 * 2. While walking tree, whenever a single derive simplefilter is encountered,
	 * this filter is pushed to the corresponding stack
	 * 2. Whenever an OR operator is encountered, all the filter stack of
	 * that OR involving derived table are emptied and null candidate of each
	 * stacked filter needs to be reset (not null)
	 */
	ParseTree* pt = csep->filters();
	map<string, ParseTree*> derivedTbFilterMap;
	if (horizontalOptimization && pt)
	{
		pt->walk(setDerivedTable);
		setDerivedFilter(pt, derivedTbFilterMap, derivedTbList);
		csep->filters(pt);
	}

	// AND the filters of individual stack to the derived table filter tree
	// @todo union filters.
	// @todo outer join complication
	map<string, ParseTree*>::iterator mapIt;
	for (uint i = 0; i < derivedTbList.size(); i++)
	{
		erydbSelectExecutionPlan *plan = dynamic_cast<erydbSelectExecutionPlan*>(derivedTbList[i].get());
		erydbSelectExecutionPlan::ReturnedColumnList derivedColList = plan->returnedCols();
		mapIt = derivedTbFilterMap.find(plan->derivedTbAlias());

		if (mapIt != derivedTbFilterMap.end())
		{
			// replace all derived column of this filter with real column from
//.........这里部分代码省略.........

    void selectExecutionPlan_1() {
        cout << "SQL: select r_regionkey from region, nation where n_regionkey = r_regionkey and n_regionkey = 2;" << endl;
        CalpontSelectExecutionPlan csep;
        CalpontSelectExecutionPlan::ReturnedColumnList colList;
        ParseTree* filterList;
        
        // returned columns
        SimpleColumn r_regionkey("tpch.region.r_regionkey");
        SimpleColumn n_regionkey("tpch.nation.n_regionkey");
        SimpleColumn p_partkey("tpch.part.p_partkey");
        SimpleColumn n_name("tpch.nation.n_name");
        SimpleColumn c_custkey("tpch.customer.c_custkey");

        colList.push_back(new SimpleColumn(r_regionkey));
               
        // filters
        CalpontSelectExecutionPlan::Parser parser;
        std::vector<Token> tokens;
        
        //tokens.push_back(Token(new Operator("(")));
        //tokens.push_back(Token(new Operator(")")));
        
        tokens.push_back(Token(new SimpleFilter(new Operator("="),
				new SimpleColumn(r_regionkey),
				new SimpleColumn(n_regionkey))));
        
        tokens.push_back(Token(new Operator("and")));

        tokens.push_back(Token(new SimpleFilter(new Operator("="),
				new SimpleColumn(r_regionkey),
				new SimpleColumn(c_custkey))));
        
        tokens.push_back(Token(new Operator("and")));

        tokens.push_back(Token(new Operator("(")));

        tokens.push_back(Token(new SimpleFilter(new Operator("="),
				new SimpleColumn(n_regionkey),
				new ConstantColumn("779"))));
        
        tokens.push_back(Token(new Operator("or")));
        
        tokens.push_back(Token(new SimpleFilter(new Operator("!="),
				new SimpleColumn(n_name),
				new ConstantColumn("'ASIA'"))));
        
        tokens.push_back(Token(new Operator(")")));

        tokens.push_back(Token(new Operator ("and")));
        
        tokens.push_back(Token(new Operator("(")));

        tokens.push_back(Token(new SimpleFilter(new Operator("<"),
				new SimpleColumn(n_regionkey),
				new ConstantColumn("77"))));
        
        tokens.push_back(Token(new Operator("or")));
        
        tokens.push_back(Token(new SimpleFilter(new Operator(">"),
				new SimpleColumn(p_partkey),
				new ConstantColumn("7007"))));
        
        tokens.push_back(Token(new Operator(")")));

        filterList = parser.parse(tokens.begin(), tokens.end());
        
        // draw filterList tree
        filterList->drawTree("selectExecutionPlan_1.dot");
                     
        // calpont execution plan        
        csep.returnedCols (colList);
        csep.filters (filterList);
        cout << "\nCalpont Execution Plan:" << endl;
        cout << csep << endl;
        cout << " --- end of test 1 ---" << endl;

			filterList->walk(walkfnString);

    }