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https://github.com/ClickHouse/ClickHouse.git
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83 lines
2.8 KiB
C++
83 lines
2.8 KiB
C++
#include <Parsers/ASTSubquery.h>
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#include <Parsers/queryToString.h>
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#include <Storages/transformQueryForExternalDatabaseAnalyzer.h>
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#include <Parsers/ASTSelectWithUnionQuery.h>
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#include <Analyzer/InDepthQueryTreeVisitor.h>
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#include <Columns/ColumnConst.h>
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#include <Analyzer/QueryNode.h>
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#include <Analyzer/ConstantNode.h>
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#include <Analyzer/ConstantValue.h>
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#include <DataTypes/DataTypesNumber.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 UNSUPPORTED_METHOD;
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}
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namespace
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{
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class PrepareForExternalDatabaseVisitor : public InDepthQueryTreeVisitor<PrepareForExternalDatabaseVisitor>
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{
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public:
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using Base = InDepthQueryTreeVisitor<PrepareForExternalDatabaseVisitor>;
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using Base::Base;
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static void visitImpl(QueryTreeNodePtr & node)
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{
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auto * constant_node = node->as<ConstantNode>();
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if (constant_node)
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{
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auto result_type = constant_node->getResultType();
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if (isDate(result_type) || isDateTime(result_type) || isDateTime64(result_type))
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{
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/// Use string representation of constant date and time values
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/// The code is ugly - how to convert artbitrary Field to proper string representation?
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/// (maybe we can just consider numbers as unix timestamps?)
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auto result_column = result_type->createColumnConst(1, constant_node->getValue());
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const IColumn & inner_column = assert_cast<const ColumnConst &>(*result_column).getDataColumn();
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WriteBufferFromOwnString out;
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result_type->getDefaultSerialization()->serializeText(inner_column, 0, out, FormatSettings());
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node = std::make_shared<ConstantNode>(std::make_shared<ConstantValue>(out.str(), result_type));
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}
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}
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}
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};
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}
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ASTPtr getASTForExternalDatabaseFromQueryTree(const QueryTreeNodePtr & query_tree)
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{
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auto new_tree = query_tree->clone();
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PrepareForExternalDatabaseVisitor visitor;
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visitor.visit(new_tree);
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const auto * query_node = new_tree->as<QueryNode>();
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auto query_node_ast = query_node->toAST({ .add_cast_for_constants = false, .fully_qualified_identifiers = false });
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const IAST * ast = query_node_ast.get();
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if (const auto * ast_subquery = ast->as<ASTSubquery>())
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ast = ast_subquery->children.at(0).get();
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const auto * union_ast = ast->as<ASTSelectWithUnionQuery>();
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if (!union_ast)
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throw Exception(ErrorCodes::UNSUPPORTED_METHOD, "QueryNode AST ({}) is not a ASTSelectWithUnionQuery", query_node_ast->getID());
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if (union_ast->list_of_selects->children.size() != 1)
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throw Exception(ErrorCodes::UNSUPPORTED_METHOD, "QueryNode AST is not a single ASTSelectQuery, got {}", union_ast->list_of_selects->children.size());
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return union_ast->list_of_selects->children.at(0);
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}
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}
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