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