name : select_handler.h /* Copyright (c) 2018, 2019 MariaDB This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #ifndef SELECT_HANDLER_INCLUDED #define SELECT_HANDLER_INCLUDED #include "mariadb.h" #include "sql_priv.h" /** @class select_handler This interface class is to be used for execution of select queries by foreign engines */ class select_handler { public: THD *thd; handlerton *ht; SELECT_LEX *select; // Select to be excuted /* Temporary table where all results should be stored in record[0] The table has a field for every item from the select_lex::item_list. The table is actually never filled. Only its record buffer is used. */ TABLE *table; List<Item> result_columns; bool is_analyze; bool send_result_set_metadata(); bool send_data(); select_handler(THD *thd_arg, handlerton *ht_arg); virtual ~select_handler(); int execute(); virtual bool prepare(); static TABLE *create_tmp_table(THD *thd, SELECT_LEX *sel); protected: /* Functions to scan the select result set. All these returns 0 if ok, error code in case of error. */ /* Initialize the process of producing rows of result set */ virtual int init_scan() = 0; /* Put the next produced row of the result set in table->record[0] and return 0. Return HA_ERR_END_OF_FILE if there are no more rows, return other error number in case of fatal error. */ virtual int next_row() = 0; /* Finish scanning */ virtual int end_scan() = 0; /* Report errors */ virtual void print_error(int error, myf errflag); bool send_eof(); }; #endif /* SELECT_HANDLER_INCLUDED */