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27c3abde30
MDEV-17631 select_handler for a full query pushdown Added comments and file headers for files introduced in these tasks.
72 lines
2 KiB
Objective-C
72 lines
2 KiB
Objective-C
/*
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Copyright (c) 2018, 2019 MariaDB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#ifndef SELECT_HANDLER_INCLUDED
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#define SELECT_HANDLER_INCLUDED
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#include "mariadb.h"
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#include "sql_priv.h"
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/**
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@class select_handler
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This interface class is to be used for execution of select queries
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by foreign engines
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*/
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class select_handler
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{
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public:
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THD *thd;
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handlerton *ht;
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SELECT_LEX *select; // Select to be excuted
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/*
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Temporary table where all results should be stored in record[0]
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The table has a field for every item from the select_lex::item_list.
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The table is actually never filled. Only its record buffer is used.
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*/
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TABLE *table;
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select_handler(THD *thd_arg, handlerton *ht_arg)
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: thd(thd_arg), ht(ht_arg), table(0) {}
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virtual ~select_handler() {}
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/*
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Functions to scan the select result set.
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All these returns 0 if ok, error code in case of error.
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*/
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/* Initialize the process of producing rows of result set */
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virtual int init_scan() = 0;
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/*
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Put the next produced row of the result set in table->record[0]
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and return 0. Return HA_ERR_END_OF_FILE if there are no more rows,
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return other error number in case of fatal error.
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*/
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virtual int next_row() = 0;
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/* Finish scanning */
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virtual int end_scan() = 0;
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/* Report errors */
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virtual void print_error(int error, myf errflag);
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};
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#endif /* SELECT_HANDLER_INCLUDED */
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