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#include <Interpreters/SelectIntersectExceptQueryVisitor.h>
#include <Parsers/ASTExpressionList.h>
#include <Parsers/ASTSelectWithUnionQuery.h>
#include <Common/typeid_cast.h>
#include <Core/SettingsEnums.h>
#include <Parsers/SelectUnionMode.h>
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
extern const int EXPECTED_ALL_OR_DISTINCT;
}
/*
* Note: there is a difference between intersect and except behaviour.
* `intersect` is supposed to be a part of the last SelectQuery, i.e. the sequence with no parenthesis:
* select 1 union all select 2 except select 1 intersect 2 except select 2 union distinct select 5;
* is interpreted as:
* select 1 union all select 2 except (select 1 intersect 2) except select 2 union distinct select 5;
* Whereas `except` is applied to all left union part like:
* (((select 1 union all select 2) except (select 1 intersect 2)) except select 2) union distinct select 5;
**/
void SelectIntersectExceptQueryMatcher::visit(ASTPtr & ast, Data & data)
{
if (auto * select_union = ast->as<ASTSelectWithUnionQuery>())
visit(*select_union, data);
}
void SelectIntersectExceptQueryMatcher::visit(ASTSelectWithUnionQuery & ast, Data & data)
{
auto union_modes = std::move(ast.list_of_modes);
if (union_modes.empty())
return;
auto selects = std::move(ast.list_of_selects->children);
if (union_modes.size() + 1 != selects.size())
throw Exception(ErrorCodes::LOGICAL_ERROR, "Incorrect ASTSelectWithUnionQuery (modes: {}, selects: {})",
union_modes.size(), selects.size());
std::reverse(selects.begin(), selects.end());
ASTs children = {selects.back()};
selects.pop_back();
SelectUnionModes modes;
for (auto & mode : union_modes)
{
/// Rewrite intersect / except mode
if (mode == SelectUnionMode::EXCEPT_DEFAULT)
{
if (data.except_default_mode == SetOperationMode::ALL)
mode = SelectUnionMode::EXCEPT_ALL;
else if (data.except_default_mode == SetOperationMode::DISTINCT)
mode = SelectUnionMode::EXCEPT_DISTINCT;
else
throw Exception(DB::ErrorCodes::EXPECTED_ALL_OR_DISTINCT,
"Expected ALL or DISTINCT in EXCEPT query, because setting (except_default_mode) is empty");
}
else if (mode == SelectUnionMode::INTERSECT_DEFAULT)
{
if (data.intersect_default_mode == SetOperationMode::ALL)
mode = SelectUnionMode::INTERSECT_ALL;
else if (data.intersect_default_mode == SetOperationMode::DISTINCT)
mode = SelectUnionMode::INTERSECT_DISTINCT;
else
throw Exception(DB::ErrorCodes::EXPECTED_ALL_OR_DISTINCT,
"Expected ALL or DISTINCT in INTERSECT query, because setting (intersect_default_mode) is empty");
}
switch (mode)
{
case SelectUnionMode::EXCEPT_ALL:
case SelectUnionMode::EXCEPT_DISTINCT:
{
auto left = std::make_shared<ASTSelectWithUnionQuery>();
left->union_mode = mode == SelectUnionMode::EXCEPT_ALL ? SelectUnionMode::UNION_ALL : SelectUnionMode::UNION_DISTINCT;
left->list_of_selects = std::make_shared<ASTExpressionList>();
left->children.push_back(left->list_of_selects);
left->list_of_selects->children = std::move(children);
left->list_of_modes = std::move(modes);
modes = {};
auto right = selects.back();
selects.pop_back();
auto except_node = std::make_shared<ASTSelectIntersectExceptQuery>();
except_node->final_operator = mode == SelectUnionMode::EXCEPT_ALL
? ASTSelectIntersectExceptQuery::Operator::EXCEPT_ALL
: ASTSelectIntersectExceptQuery::Operator::EXCEPT_DISTINCT;
except_node->children = {left, right};
children = {except_node};
break;
}
case SelectUnionMode::INTERSECT_ALL:
case SelectUnionMode::INTERSECT_DISTINCT:
{
bool from_except = false;
const auto * except_ast = typeid_cast<const ASTSelectIntersectExceptQuery *>(children.back().get());
if (except_ast
&& (except_ast->final_operator == ASTSelectIntersectExceptQuery::Operator::EXCEPT_ALL
|| except_ast->final_operator == ASTSelectIntersectExceptQuery::Operator::EXCEPT_DISTINCT))
from_except = true;
ASTPtr left;
if (from_except)
{
left = std::move(children.back()->children[1]);
}
else
{
left = children.back();
children.pop_back();
}
auto right = selects.back();
selects.pop_back();
auto intersect_node = std::make_shared<ASTSelectIntersectExceptQuery>();
intersect_node->final_operator = mode == SelectUnionMode::INTERSECT_ALL
? ASTSelectIntersectExceptQuery::Operator::INTERSECT_ALL
: ASTSelectIntersectExceptQuery::Operator::INTERSECT_DISTINCT;
intersect_node->children = {left, right};
if (from_except)
children.back()->children[1] = std::move(intersect_node);
else
children.push_back(std::move(intersect_node));
break;
}
default:
{
auto right = selects.back();
selects.pop_back();
children.emplace_back(std::move(right));
modes.push_back(mode);
break;
}
}
}
if (!selects.empty())
{
auto right = selects.back();
selects.pop_back();
children.emplace_back(std::move(right));
}
ast.list_of_selects->children = std::move(children);
ast.list_of_modes = std::move(modes);
}
}
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