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/* Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
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 02110-1335 USA */
#ifndef SQL_DELETE_INCLUDED
#define SQL_DELETE_INCLUDED
#include "my_base.h" /* ha_rows */
#include "sql_class.h" /* enum_duplicates */
#include "sql_cmd.h" // Sql_cmd_dml
#include "sql_base.h"
class THD;
struct TABLE_LIST;
class Item;
class select_result;
typedef class Item COND;
template <typename T> class SQL_I_List;
/**
@class Sql_cmd_delete - class used for any DELETE statements
This class is derived from Sql_cmd_dml and contains implementations
for abstract virtual function of the latter such as precheck() and
prepare_inner(). It also overrides the implementation of execute_inner()
providing a special handling for single-table delete statements that
are not converted to multi-table delete.
The class provides an object of the DML_prelocking_strategy class
for the virtual function get_dml_prelocking_strategy().
*/
class Sql_cmd_delete final : public Sql_cmd_dml
{
public:
Sql_cmd_delete(bool multitable_arg)
: orig_multitable(multitable_arg), multitable(multitable_arg),
save_protocol(NULL)
{}
enum_sql_command sql_command_code() const override
{
return orig_multitable ? SQLCOM_DELETE_MULTI : SQLCOM_DELETE;
}
DML_prelocking_strategy *get_dml_prelocking_strategy() override
{
return &dml_prelocking_strategy;
}
bool processing_as_multitable_delete_prohibited(THD *thd);
bool is_multitable() const { return multitable; }
void set_as_multitable() { multitable= true; }
void remove_order_by_without_limit(THD *thd);
protected:
/**
@brief Perform precheck of table privileges for delete statements
*/
bool precheck(THD *thd) override;
/**
@brief Perform context analysis for delete statements
*/
bool prepare_inner(THD *thd) override;
/**
@brief Perform optimization and execution actions needed for deletes
*/
bool execute_inner(THD *thd) override;
private:
/**
@biefSpecial handling of single-table deletes after prepare phase
*/
bool delete_from_single_table(THD *thd);
/* Original value of the 'multitable' flag set by constructor */
const bool orig_multitable;
/*
True if the statement is a multitable delete or converted to such.
For a single-table delete this flag is set to true if the statement
is supposed to be converted to multi-table delete.
*/
bool multitable;
/* The prelocking strategy used when opening the used tables */
DML_prelocking_strategy dml_prelocking_strategy;
List<Item> empty_list; /**< auxiliary empty list used by prepare_inner() */
Protocol *save_protocol; /**< needed for ANALYZE .. DELETE .. RETURNING */
};
#endif /* SQL_DELETE_INCLUDED */
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