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dbms: Server: Performance improvement. [#METR-16778]

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This commit is contained in:
Alexey Arno 2015-07-11 18:16:59 +03:00
parent b4f65a44e9
commit 135cac6d77
3 changed files with 22 additions and 10 deletions
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5
dbms/include/DB/Parsers/ASTSelectQuery.h
View File

@ -36,11 +36,14 @@ public:
ASTPtr clone() const override; ASTPtr clone() const override;
/// Получить глубокую копию дерева первого запроса SELECT.
ASTPtr cloneFirstSelect() const;
/// Возвращает указатель на формат из последнего SELECT'а цепочки UNION ALL. /// Возвращает указатель на формат из последнего SELECT'а цепочки UNION ALL.
const IAST * getFormat() const override; const IAST * getFormat() const override;
private: private:
ASTPtr cloneImpl() const; ASTPtr cloneImpl(bool traverse_union_all) const;
public: public:
bool distinct = false; bool distinct = false;

5
dbms/src/Interpreters/InterpreterSelectQuery.cpp
View File

@ -720,10 +720,7 @@ QueryProcessingStage::Enum InterpreterSelectQuery::executeFetchColumns(BlockInpu
if (storage->isRemote()) if (storage->isRemote())
{ {
/// В случае удаленного запроса отправляем только SELECT, который выполнится. /// В случае удаленного запроса отправляем только SELECT, который выполнится.
actual_query_ptr = query_ptr->clone(); actual_query_ptr = query.cloneFirstSelect();
auto actual_select_query = static_cast<ASTSelectQuery *>(&*actual_query_ptr);
actual_select_query->prev_union_all = nullptr;
actual_select_query->next_union_all = nullptr;
} }
else else
actual_query_ptr = query_ptr; actual_query_ptr = query_ptr;

22
dbms/src/Parsers/ASTSelectQuery.cpp
View File

@ -134,7 +134,7 @@ void ASTSelectQuery::rewriteSelectExpressionList(const Names & column_names)
ASTPtr ASTSelectQuery::clone() const ASTPtr ASTSelectQuery::clone() const
{ {
ASTPtr ptr = cloneImpl(); ASTPtr ptr = cloneImpl(true);
/// Установить указатели на предыдущие запросы SELECT. /// Установить указатели на предыдущие запросы SELECT.
ASTPtr current = ptr; ASTPtr current = ptr;
@ -150,7 +150,14 @@ ASTPtr ASTSelectQuery::clone() const
return ptr; return ptr;
} }
ASTPtr ASTSelectQuery::cloneImpl() const ASTPtr ASTSelectQuery::cloneFirstSelect() const
{
ASTPtr res = cloneImpl(false);
static_cast<ASTSelectQuery *>(&*res)->prev_union_all = nullptr;
return res;
}
ASTPtr ASTSelectQuery::cloneImpl(bool traverse_union_all) const
{ {
ASTSelectQuery * res = new ASTSelectQuery(*this); ASTSelectQuery * res = new ASTSelectQuery(*this);
ASTPtr ptr{res}; ASTPtr ptr{res};
@ -187,11 +194,16 @@ ASTPtr ASTSelectQuery::cloneImpl() const
#undef CLONE #undef CLONE
if (next_union_all) if (traverse_union_all)
{ {
res->next_union_all = static_cast<const ASTSelectQuery *>(&*next_union_all)->cloneImpl(); if (next_union_all)
res->children.push_back(res->next_union_all); {
res->next_union_all = static_cast<const ASTSelectQuery *>(&*next_union_all)->cloneImpl(true);
res->children.push_back(res->next_union_all);
}
} }
else
res->next_union_all = nullptr;
return ptr; return ptr;
} }