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/* Copyright (c) 2005, 2011, 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_cursor_h_
#define _sql_cursor_h_
#include "sql_class.h" /* Query_arena */
class JOIN;
/**
@file
Declarations for implementation of server side cursors. Only
read-only non-scrollable cursors are currently implemented.
*/
/**
Server_side_cursor -- an interface for materialized
implementation of cursors. All cursors are self-contained
(created in their own memory root). For that reason they must
be deleted only using a pointer to Server_side_cursor, not to
its base class.
*/
class Server_side_cursor: protected Query_arena
{
protected:
/** Row destination used for fetch */
select_result *result;
public:
Server_side_cursor(MEM_ROOT *mem_root_arg, select_result *result_arg)
:Query_arena(mem_root_arg, STMT_INITIALIZED), result(result_arg)
{}
virtual bool is_open() const= 0;
virtual int open(JOIN *top_level_join)= 0;
virtual void fetch(ulong num_rows)= 0;
virtual void close()= 0;
virtual bool export_structure(THD *thd, Row_definition_list *defs)
{
DBUG_ASSERT(0);
return true;
}
virtual ~Server_side_cursor();
static void *operator new(size_t size, MEM_ROOT *mem_root)
{ return alloc_root(mem_root, size); }
static void operator delete(void *ptr, size_t size);
static void operator delete(void *, MEM_ROOT *){}
};
/**
Materialized_cursor -- an insensitive materialized server-side
cursor. The result set of this cursor is saved in a temporary
table at open. The cursor itself is simply an interface for the
handler of the temporary table.
*/
class Materialized_cursor: public Server_side_cursor
{
MEM_ROOT main_mem_root;
/* A fake unit to supply to select_send when fetching */
SELECT_LEX_UNIT fake_unit;
TABLE *table;
List<Item> item_list;
ulong fetch_limit;
ulong fetch_count;
bool is_rnd_inited;
public:
Materialized_cursor(select_result *result, TABLE *table);
int send_result_set_metadata(THD *thd, List<Item> &send_result_set_metadata);
bool is_open() const override { return table != 0; }
int open(JOIN *join __attribute__((unused))) override;
void fetch(ulong num_rows) override;
void close() override;
bool export_structure(THD *thd, Row_definition_list *defs) override
{
return table->export_structure(thd, defs);
}
~Materialized_cursor() override;
void on_table_fill_finished();
};
/**
Select_materialize -- a mediator between a cursor query and the
protocol. In case we were not able to open a non-materialzed
cursor, it creates an internal temporary HEAP table, and insert
all rows into it. When the table reaches max_heap_table_size,
it's converted to a MyISAM table. Later this table is used to
create a Materialized_cursor.
*/
class Select_materialize: public select_unit
{
select_result *result; /**< the result object of the caller (PS or SP) */
public:
Materialized_cursor *materialized_cursor;
Select_materialize(THD *thd_arg, select_result *result_arg):
select_unit(thd_arg), result(result_arg), materialized_cursor(0) {}
bool send_result_set_metadata(List<Item> &list, uint flags) override;
bool send_eof() override { return false; }
bool view_structure_only() const override
{
return result->view_structure_only();
}
};
int mysql_open_cursor(THD *thd, select_result *result,
Server_side_cursor **res);
#endif /* _sql_cusor_h_ */
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