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72 lines
2.9 KiB
C
72 lines
2.9 KiB
C
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#pragma once
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#include <statdaemons/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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namespace DB
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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 { return "merge"; }
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StoragePtr execute(ASTPtr ast_function, Context & context)
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{
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ASTs & args_func = dynamic_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 = dynamic_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 table_name_regexp = safeGet<const String &>(dynamic_cast<ASTLiteral &>(*args[1]).value);
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String source_database = dynamic_cast<ASTIdentifier &>(*args[0]).name;
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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, посколку по умолчанию стоит значение column
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dynamic_cast<ASTIdentifier &>(*args[0]).kind = ASTIdentifier::Database;
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return StorageMerge::create(ChooseName(), ChooseColumns(source_database, table_name_regexp, context), 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_, Context & context)
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{
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OptimizedRegularExpression table_name_regexp(table_name_regexp_);
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/// Список таблиц могут менять в другом потоке.
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Poco::ScopedLock<Poco::Mutex> lock(context.getMutex());
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context.assertDatabaseExists(source_database);
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const Tables & tables = context.getDatabases().at(source_database);
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for (Tables::const_iterator it = tables.begin(); it != tables.end(); ++it)
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if (table_name_regexp.match(it->first))
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return new NamesAndTypesList((it->second)->getColumnsList());
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throw Exception("Error whyle creating table function merge. In database " + source_database + " no one matches regular expression: " + table_name_regexp_, ErrorCodes::UNKNOWN_TABLE);
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}
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};
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}
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