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/*
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 Street, Fifth Floor, Boston, MA 02111-1301 USA */
#include "mariadb.h"
#include "sql_priv.h"
#include "sql_select.h"
#include "derived_handler.h"
/**
The methods of the Pushdown_derived class.
The objects of this class are used for pushdown of the derived tables
into engines. The main method of the class is Pushdown_derived::execute()
that initiates execution of the query specifying a derived by a foreign
engine, receives the rows of the result set and put them in a temporary
table on the server side.
The method uses only the functions of the derived_handle interface to do
this. The constructor of the class gets this interface as a parameter.
Currently a derived tables pushed into an engine is always materialized.
It could be changed if the cases when the tables is used as driving table.
*/
Pushdown_derived::Pushdown_derived(TABLE_LIST *tbl, derived_handler *h)
: derived(tbl), handler(h)
{
}
int Pushdown_derived::execute()
{
int err;
THD *thd= handler->thd;
TABLE *table= handler->table;
TMP_TABLE_PARAM *tmp_table_param= handler->tmp_table_param;
DBUG_ENTER("Pushdown_derived::execute");
if ((err= handler->init_scan()))
goto error;
while (!(err= handler->next_row()))
{
if (unlikely(thd->check_killed()))
{
handler->end_scan();
DBUG_RETURN(-1);
}
if ((err= table->file->ha_write_tmp_row(table->record[0])))
{
bool is_duplicate;
if (likely(!table->file->is_fatal_error(err, HA_CHECK_DUP)))
continue; // Distinct elimination
if (create_internal_tmp_table_from_heap(thd, table,
tmp_table_param->start_recinfo,
&tmp_table_param->recinfo,
err, 1, &is_duplicate))
DBUG_RETURN(1);
if (is_duplicate)
continue;
}
}
if (err != 0 && err != HA_ERR_END_OF_FILE)
goto error;
if ((err= handler->end_scan()))
goto error_2;
DBUG_RETURN(0);
error:
handler->end_scan();
error_2:
handler->print_error(err, MYF(0));
DBUG_RETURN(-1); // Error not sent to client
}
void derived_handler::print_error(int error, myf errflag)
{
my_error(ER_GET_ERRNO, MYF(0), error, hton_name(ht)->str);
}
void derived_handler::set_derived(TABLE_LIST *tbl)
{
derived= tbl;
table= tbl->table;
unit= tbl->derived;
select= unit->first_select();
tmp_table_param= ((select_unit *)(unit->result))->get_tmp_table_param();
}
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