Current File : //usr/include/mysql/server/private/derived_handler.h
/*
Copyright (c) 2016, 2017 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 DERIVED_HANDLER_INCLUDED
#define DERIVED_HANDLER_INCLUDED
#include "mariadb.h"
#include "sql_priv.h"
class TMP_TABLE_PARAM;
typedef class st_select_lex_unit SELECT_LEX_UNIT;
/**
@class derived_handler
This interface class is to be used for execution of queries that specify
derived table by foreign engines
*/
class derived_handler
{
public:
THD *thd;
handlerton *ht;
TABLE_LIST *derived;
/*
Temporary table where all results should be stored in record[0]
The table has a field for every item from the select list of
the specification of derived.
*/
TABLE *table;
/* The parameters if the temporary table used at its creation */
TMP_TABLE_PARAM *tmp_table_param;
SELECT_LEX_UNIT *unit; // Specifies the derived table
SELECT_LEX *select; // The first select of the specification
derived_handler(THD *thd_arg, handlerton *ht_arg)
: thd(thd_arg), ht(ht_arg), derived(0),table(0), tmp_table_param(0),
unit(0), select(0) {}
virtual ~derived_handler() = default;
/*
Functions to scan data. All these returns 0 if ok, error code in case
of error
*/
/* Initialize the process of producing rows of the derived table */
virtual int init_scan()= 0;
/*
Put the next produced row of the derived 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;
/* End prodicing rows */
virtual int end_scan()=0;
/* Report errors */
virtual void print_error(int error, myf errflag);
void set_derived(TABLE_LIST *tbl);
};
#endif /* DERIVED_HANDLER_INCLUDED */
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