dbms: development [#CONV-2944].

dbms/include/DB/Interpreters/Expression.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <set>
+
 #include <Poco/SharedPtr.h>
 
 #include <DB/Parsers/IAST.h>
@@ -58,6 +60,13 @@ private:
 	void setNotCalculated(ASTPtr ast);
 
 	void executeImpl(ASTPtr ast, Block & block);
+
+	/** Взять из блока с промежуточными результатами вычислений только столбцы, представляющие собой конечный результат.
+	  * Вернуть новый блок, в котором эти столбцы расположены в правильном порядке.
+	  */
+	Block projectResult(ASTPtr ast, Block & block);
+
+	void collectFinalColumns(ASTPtr ast, Block & src, Block & dst);
 };
 
 

dbms/src/Interpreters/Expression.cpp

@@ -34,8 +34,7 @@ void Expression::addSemantic(ASTPtr ast)
 		node->type = boost::apply_visitor(FieldToDataType(), node->value);
 	}
 
-	ASTs children = ast->children;
-	for (ASTs::iterator it = children.begin(); it != children.end(); ++it)
+	for (ASTs::iterator it = ast->children.begin(); it != ast->children.end(); ++it)
 		addSemantic(*it);
 }
 
@@ -44,8 +43,7 @@ void Expression::checkTypes(ASTPtr ast)
 {
 	/// Обход в глубину
 	
-	ASTs children = ast->children;
-	for (ASTs::iterator it = children.begin(); it != children.end(); ++it)
+	for (ASTs::iterator it = ast->children.begin(); it != ast->children.end(); ++it)
 		checkTypes(*it);
 
 	if (ASTFunction * node = dynamic_cast<ASTFunction *>(&*ast))
@@ -81,8 +79,7 @@ void Expression::glueTreeImpl(ASTPtr ast, Subtrees & subtrees)
 {
 	/// Обход в глубину
 
-	ASTs children = ast->children;
-	for (ASTs::iterator it = children.begin(); it != children.end(); ++it)
+	for (ASTs::iterator it = ast->children.begin(); it != ast->children.end(); ++it)
 		glueTreeImpl(*it, subtrees);
 
 	if (ASTFunction * node = dynamic_cast<ASTFunction *>(&*ast))
@@ -110,8 +107,7 @@ void Expression::glueTreeImpl(ASTPtr ast, Subtrees & subtrees)
 void Expression::setNotCalculated(ASTPtr ast)
 {
 	ast->calculated = false;
-	ASTs children = ast->children;
-	for (ASTs::iterator it = children.begin(); it != children.end(); ++it)
+	for (ASTs::iterator it = ast->children.begin(); it != ast->children.end(); ++it)
 		setNotCalculated(*it);
 }
 
@@ -120,6 +116,7 @@ void Expression::execute(Block & block)
 {
 	setNotCalculated(ast);
 	executeImpl(ast, block);
+	block = projectResult(ast, block);
 }
 
 
@@ -127,8 +124,7 @@ void Expression::executeImpl(ASTPtr ast, Block & block)
 {
 	/// Обход в глубину
 
-	ASTs children = ast->children;
-	for (ASTs::iterator it = children.begin(); it != children.end(); ++it)
+	for (ASTs::iterator it = ast->children.begin(); it != ast->children.end(); ++it)
 		executeImpl(*it, block);
 
 	if (ast->calculated)
@@ -190,4 +186,33 @@ void Expression::executeImpl(ASTPtr ast, Block & block)
 }
 
 
+Block Expression::projectResult(ASTPtr ast, Block & block)
+{
+	Block res;
+	collectFinalColumns(ast, block, res);
+	return res;
+}
+
+
+void Expression::collectFinalColumns(ASTPtr ast, Block & src, Block & dst)
+{
+	if (ASTExpressionList * node = dynamic_cast<ASTExpressionList *>(&*ast))
+	{
+		for (ASTs::iterator it = node->children.begin(); it != node->children.end(); ++it)
+		{
+			if (ASTIdentifier * ident = dynamic_cast<ASTIdentifier *>(&**it))
+				dst.insert(src.getByName(ident->name));
+			else if (ASTFunction * func = dynamic_cast<ASTFunction *>(&**it))
+				for (ColumnNumbers::const_iterator jt = func->return_column_numbers.begin(); jt != func->return_column_numbers.end(); ++jt)
+					dst.insert(src.getByPosition(*jt));
+			else
+				dst.insert(src.getByName((*it)->getTreeID()));
+		}
+	}
+	else
+		for (ASTs::iterator it = ast->children.begin(); it != ast->children.end(); ++it)
+			 collectFinalColumns(*it, src, dst);
+}
+
+	
 }

dbms/src/Interpreters/tests/expression.cpp

@@ -1,6 +1,7 @@
 #include <iostream>
+#include <iomanip>
 
-#include <mysqlxx/mysqlxx.h>
+#include <Poco/Stopwatch.h>
 
 #include <DB/IO/WriteBufferFromOStream.h>
 
@@ -13,6 +14,7 @@
 #include <DB/Parsers/formatAST.h>
 
 #include <DB/DataStreams/TabSeparatedRowOutputStream.h>
+#include <DB/DataStreams/LimitBlockInputStream.h>
 #include <DB/DataStreams/copyData.h>
 
 #include <DB/Interpreters/Expression.h>
@@ -105,7 +107,7 @@ int main(int argc, char ** argv)
 
 		dump(*ast);
 
-		size_t n = 10;
+		size_t n = argc == 2 ? atoi(argv[1]) : 10;
 
 		DB::Block block;
 		DB::ColumnWithNameAndType column_x;
@@ -121,17 +123,29 @@ int main(int argc, char ** argv)
 
 		block.insert(column_x);
 
-		expression.execute(block);
+		{
+			Poco::Stopwatch stopwatch;
+			stopwatch.start();
+
+			expression.execute(block);
+
+			stopwatch.stop();
+			std::cout << std::fixed << std::setprecision(2)
+				<< "Elapsed " << stopwatch.elapsed() / 1000000.0 << " sec."
+				<< ", " << n * 1000000 / stopwatch.elapsed() << " rows/sec."
+				<< std::endl;
+		}
 		
 		DB::DataTypes * data_types = new DB::DataTypes;
 		for (size_t i = 0; i < block.columns(); ++i)
 			data_types->push_back(block.getByPosition(i).type);
 
-		OneBlockInputStream is(block);
+		OneBlockInputStream * is = new OneBlockInputStream(block);
+		DB::LimitBlockInputStream lis(is, 10, std::max(0, static_cast<int>(n) - 10));
 		DB::WriteBufferFromOStream out_buf(std::cout);
 		DB::TabSeparatedRowOutputStream os(out_buf, data_types);
 
-		DB::copyData(is, os);
+		DB::copyData(lis, os);
 	}
 	catch (const DB::Exception & e)
 	{