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96 lines
3.2 KiB
C++
96 lines
3.2 KiB
C++
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#pragma once
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#include <DB/Common/OptimizedRegularExpression.h>
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#include <DB/Storages/StorageFactory.h>
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#include <DB/Storages/StorageMerge.h>
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#include <DB/Parsers/ASTExpressionList.h>
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#include <DB/Parsers/ASTIdentifier.h>
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#include <DB/Parsers/ASTLiteral.h>
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#include <DB/TableFunctions/ITableFunction.h>
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#include <DB/Interpreters/reinterpretAsIdentifier.h>
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#include <DB/Databases/IDatabase.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 NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
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extern const int UNKNOWN_TABLE;
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}
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/*
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* merge(db_name, tables_regexp)- создаёт временный StorageMerge.
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* Cтруктура таблицы берётся из первой попавшейся таблицы, подходящей под регексп.
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* Если такой таблицы нет - кидается исключение.
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*/
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class TableFunctionMerge: public ITableFunction
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{
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public:
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std::string getName() const override { return "merge"; }
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StoragePtr execute(ASTPtr ast_function, Context & context) const override
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{
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ASTs & args_func = typeid_cast<ASTFunction &>(*ast_function).children;
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if (args_func.size() != 1)
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throw Exception("Storage Merge requires exactly 2 parameters"
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" - name of source database and regexp for table names.",
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ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
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ASTs & args = typeid_cast<ASTExpressionList &>(*args_func.at(0)).children;
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if (args.size() != 2)
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throw Exception("Storage Merge requires exactly 2 parameters"
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" - name of source database and regexp for table names.",
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ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
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String source_database = reinterpretAsIdentifier(args[0], context).name;
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String table_name_regexp = safeGet<const String &>(typeid_cast<ASTLiteral &>(*args[1]).value);
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/// В InterpreterSelectQuery будет создан ExpressionAnalzyer, который при обработке запроса наткнется на этот Identifier.
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/// Нам необходимо его пометить как имя базы данных, поскольку по умолчанию стоит значение column
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typeid_cast<ASTIdentifier &>(*args[0]).kind = ASTIdentifier::Database;
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return StorageMerge::create(getName(), chooseColumns(source_database, table_name_regexp, context),
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source_database, table_name_regexp, context);
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}
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private:
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NamesAndTypesListPtr chooseColumns(const String & source_database, const String & table_name_regexp_, const Context & context) const
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{
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OptimizedRegularExpression table_name_regexp(table_name_regexp_);
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StoragePtr any_table;
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{
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auto database = context.getDatabase(source_database);
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auto iterator = database->getIterator();
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while (iterator->isValid())
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{
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if (table_name_regexp.match(iterator->name()))
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{
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any_table = iterator->table();
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break;
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}
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iterator->next();
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}
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}
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if (!any_table)
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throw Exception("Error while executing table function merge. In database " + source_database + " no one matches regular expression: " + table_name_regexp_, ErrorCodes::UNKNOWN_TABLE);
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auto table_lock = any_table->lockStructure(false);
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return new NamesAndTypesList(any_table->getColumnsList());
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}
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};
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}
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