diff --git a/Data/include/Poco/Data/RecordSet.h b/Data/include/Poco/Data/RecordSet.h
index 4451a2acd..7aa2048a1 100644
--- a/Data/include/Poco/Data/RecordSet.h
+++ b/Data/include/Poco/Data/RecordSet.h
@@ -279,6 +279,8 @@ private:
 	{
 		typedef const InternalExtraction<T,C>* ExtractionVecPtr;
 
+		bool typeFound = false;
+
 		const AbstractExtractionVec& rExtractions = extractions();
 		AbstractExtractionVec::const_iterator it = rExtractions.begin();
 		AbstractExtractionVec::const_iterator end = rExtractions.end();
@@ -289,13 +291,17 @@ private:
 
 			if (pExtraction)
 			{
+				typeFound = true;
 				const Column<T,C>& col = pExtraction->column();
 				if (0 == Poco::icompare(name, col.name()))
 					return col.position();
 			}
 		}
 
-		throw NotFoundException(format("Unknown column name: %s", name));
+		if (typeFound)
+			throw NotFoundException(format("Column name: %s", name));
+		else
+			throw NotFoundException(format("Column type: %s, name: %s", typeid(C).name(), name));
 	}
 
 	std::size_t    _currentRow;
diff --git a/Data/include/Poco/Data/Statement.h b/Data/include/Poco/Data/Statement.h
index 647bb033f..675bf572b 100644
--- a/Data/include/Poco/Data/Statement.h
+++ b/Data/include/Poco/Data/Statement.h
@@ -114,10 +114,12 @@ class Data_API Statement
 {
 public:
 	typedef void (*Manipulator)(Statement&);
-	typedef Poco::UInt32 ResultType;
-	typedef ActiveResult<ResultType> Result;
-	typedef SharedPtr<Result> ResultPtr;
+
+	typedef Poco::UInt32                                  ResultType;
+	typedef ActiveResult<ResultType>                      Result;
+	typedef SharedPtr<Result>                             ResultPtr;
 	typedef ActiveMethod<ResultType, void, StatementImpl> AsyncExecMethod;
+	typedef SharedPtr<AsyncExecMethod>                    AsyncExecMethodPtr;
 
 	enum Storage
 	{
@@ -203,7 +205,7 @@ public:
 		/// Stops when either a limit is hit or the whole statement was executed.
 		/// Returns immediately. For statements returning data, the number of rows extracted is 
 		/// available by calling wait() method on either the returned value or the statement itself.
-		/// When executed on otherwise synchronous statement, this method does not alter the
+		/// When executed on a synchronous statement, this method does not alter the
 		/// statement's synchronous nature.
 
 	void setAsync(bool async = true);
@@ -271,13 +273,13 @@ private:
 	const Result& doAsyncExec();
 		/// Asynchronously executes the statement.
 
-	StatementImplPtr  _ptr;
+	StatementImplPtr _ptr;
 
 	// asynchronous execution related members
-	bool              _isAsync;
-	mutable ResultPtr _pResult;
-	Mutex             _mutex;
-	AsyncExecMethod   _asyncExec;
+	bool               _async;
+	mutable ResultPtr  _pResult;
+	Mutex              _mutex;
+	AsyncExecMethodPtr _pAsyncExec;
 };
 
 
@@ -430,15 +432,9 @@ inline bool Statement::isNull(std::size_t col, std::size_t row) const
 }
 
 
-inline void Statement::setAsync(bool async)
-{
-	_isAsync = async;
-}
-
-
 inline bool Statement::isAsync() const
 {
-	return _isAsync;
+	return _async;
 }
 
 
diff --git a/Data/src/Statement.cpp b/Data/src/Statement.cpp
index 03a4fed04..ea667a31e 100644
--- a/Data/src/Statement.cpp
+++ b/Data/src/Statement.cpp
@@ -50,15 +50,14 @@ namespace Data {
 
 Statement::Statement(StatementImpl* pImpl):
 	_ptr(pImpl),
-	_isAsync(false),
-	_asyncExec(_ptr, &StatementImpl::execute)
+	_async(false)
 {
 	poco_check_ptr (pImpl);
 }
 
 
 Statement::Statement(Session& session):
-	_asyncExec(_ptr, &StatementImpl::execute)
+	_async(false)
 {
 	reset(session);
 }
@@ -66,9 +65,9 @@ Statement::Statement(Session& session):
 
 Statement::Statement(const Statement& stmt):
 	_ptr(stmt._ptr),
-	_isAsync(stmt._isAsync),
+	_async(stmt._async),
 	_pResult(stmt._pResult),
-	_asyncExec(_ptr, &StatementImpl::execute)
+	_pAsyncExec(stmt._pAsyncExec)
 {
 }
 
@@ -89,12 +88,20 @@ Statement& Statement::operator = (const Statement& stmt)
 void Statement::swap(Statement& other)
 {
 	std::swap(_ptr, other._ptr);
-	std::swap(_isAsync, other._isAsync);
-	std::swap(_asyncExec, other._asyncExec);
+	std::swap(_async, other._async);
+	std::swap(_pAsyncExec, other._pAsyncExec);
 	std::swap(_pResult, other._pResult);
 }
 
 
+Statement& Statement::reset(Session& session)
+{
+	Statement stmt(session.createStatementImpl());
+	swap(stmt);
+	return *this;
+}
+
+
 Statement::ResultType Statement::execute()
 {
 	Mutex::ScopedLock lock(_mutex);
@@ -129,12 +136,23 @@ const Statement::Result& Statement::executeAsync()
 const Statement::Result& Statement::doAsyncExec()
 {
 	if (done()) _ptr->reset();
-	_pResult = new Result(_asyncExec());
+	if (!_pAsyncExec)
+		_pAsyncExec = new AsyncExecMethod(_ptr, &StatementImpl::execute);
+	poco_check_ptr (_pAsyncExec);
+	_pResult = new Result((*_pAsyncExec)());
 	poco_check_ptr (_pResult);
 	return *_pResult;
 }
 
 
+void Statement::setAsync(bool async)
+{
+	_async = async;
+	if (_async && !_pAsyncExec)
+		_pAsyncExec = new AsyncExecMethod(_ptr, &StatementImpl::execute);
+}
+
+
 Statement::ResultType Statement::wait(long milliseconds)
 {
 	if (!_pResult) return 0;
@@ -151,14 +169,6 @@ Statement::ResultType Statement::wait(long milliseconds)
 }
 
 
-Statement& Statement::reset(Session& session)
-{
-	Statement stmt(session.createStatementImpl());
-	swap(stmt);
-	return *this;
-}
-
-
 const std::string& Statement::getStorage() const
 {
 	switch (storage())