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7781fc12ed
521 -> 77 files requiring changes
145 lines
5.2 KiB
C++
145 lines
5.2 KiB
C++
#include <Interpreters/NormalizeSelectWithUnionQueryVisitor.h>
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#include <Parsers/ASTExpressionList.h>
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#include <Parsers/ASTSelectIntersectExceptQuery.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 EXPECTED_ALL_OR_DISTINCT;
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extern const int LOGICAL_ERROR;
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}
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void NormalizeSelectWithUnionQueryMatcher::getSelectsFromUnionListNode(ASTPtr ast_select, ASTs & selects)
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{
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if (const auto * inner_union = ast_select->as<ASTSelectWithUnionQuery>())
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{
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for (const auto & child : inner_union->list_of_selects->children)
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getSelectsFromUnionListNode(child, selects);
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return;
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}
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selects.push_back(ast_select);
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}
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void NormalizeSelectWithUnionQueryMatcher::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 NormalizeSelectWithUnionQueryMatcher::visit(ASTSelectWithUnionQuery & ast, Data & data)
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{
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auto & union_modes = ast.list_of_modes;
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ASTs selects;
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const auto & select_list = ast.list_of_selects->children;
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if (select_list.empty())
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throw Exception(ErrorCodes::LOGICAL_ERROR, "Got empty list of selects for ASTSelectWithUnionQuery");
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/// Since nodes are traversed from bottom to top, we can also collect union modes from children up to parents.
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SelectUnionModesSet current_set_of_modes;
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bool distinct_found = false;
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int i;
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for (i = union_modes.size() - 1; i >= 0; --i)
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{
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current_set_of_modes.insert(union_modes[i]);
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if (const auto * union_ast = typeid_cast<const ASTSelectWithUnionQuery *>(select_list[i + 1].get()))
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{
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const auto & current_select_modes = union_ast->set_of_modes;
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current_set_of_modes.insert(current_select_modes.begin(), current_select_modes.end());
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}
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if (distinct_found)
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continue;
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/// Rewrite UNION Mode
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if (union_modes[i] == SelectUnionMode::Unspecified)
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{
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if (data.union_default_mode == UnionMode::ALL)
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union_modes[i] = SelectUnionMode::ALL;
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else if (data.union_default_mode == UnionMode::DISTINCT)
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union_modes[i] = SelectUnionMode::DISTINCT;
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else
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throw Exception(
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"Expected ALL or DISTINCT in SelectWithUnion query, because setting (union_default_mode) is empty",
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DB::ErrorCodes::EXPECTED_ALL_OR_DISTINCT);
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}
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if (union_modes[i] == SelectUnionMode::ALL)
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{
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if (auto * inner_union = select_list[i + 1]->as<ASTSelectWithUnionQuery>();
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inner_union && inner_union->union_mode == SelectUnionMode::ALL)
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{
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/// Inner_union is an UNION ALL list, just lift up
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for (auto child = inner_union->list_of_selects->children.rbegin(); child != inner_union->list_of_selects->children.rend();
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++child)
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selects.push_back(*child);
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}
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else
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selects.push_back(select_list[i + 1]);
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}
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/// flatten all left nodes and current node to a UNION DISTINCT list
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else if (union_modes[i] == SelectUnionMode::DISTINCT)
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{
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auto distinct_list = std::make_shared<ASTSelectWithUnionQuery>();
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distinct_list->list_of_selects = std::make_shared<ASTExpressionList>();
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distinct_list->children.push_back(distinct_list->list_of_selects);
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for (int j = 0; j <= i + 1; ++j)
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{
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getSelectsFromUnionListNode(select_list[j], distinct_list->list_of_selects->children);
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}
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distinct_list->union_mode = SelectUnionMode::DISTINCT;
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distinct_list->is_normalized = true;
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selects.push_back(std::move(distinct_list));
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distinct_found = true;
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}
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}
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if (const auto * union_ast = typeid_cast<const ASTSelectWithUnionQuery *>(select_list[0].get()))
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{
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const auto & current_select_modes = union_ast->set_of_modes;
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current_set_of_modes.insert(current_select_modes.begin(), current_select_modes.end());
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}
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/// No UNION DISTINCT or only one child in select_list
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if (!distinct_found)
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{
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if (auto * inner_union = select_list[0]->as<ASTSelectWithUnionQuery>();
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inner_union && inner_union->union_mode == SelectUnionMode::ALL)
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{
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/// Inner_union is an UNION ALL list, just lift it up
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for (auto child = inner_union->list_of_selects->children.rbegin(); child != inner_union->list_of_selects->children.rend();
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++child)
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selects.push_back(*child);
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}
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else
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selects.push_back(select_list[0]);
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}
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/// Just one union type child, lift it up
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if (selects.size() == 1 && selects[0]->as<ASTSelectWithUnionQuery>())
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{
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ast = *(selects[0]->as<ASTSelectWithUnionQuery>());
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ast.set_of_modes = std::move(current_set_of_modes);
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return;
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}
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// reverse children list
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std::reverse(selects.begin(), selects.end());
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ast.is_normalized = true;
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ast.union_mode = SelectUnionMode::ALL;
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ast.set_of_modes = std::move(current_set_of_modes);
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ast.list_of_selects->children = std::move(selects);
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}
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}
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