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131 lines
4.0 KiB
C++
131 lines
4.0 KiB
C++
/* Copyright (c) 2005, 2011, Oracle and/or its affiliates. All rights reserved.
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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 02110-1335 USA */
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#ifndef _sql_cursor_h_
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#define _sql_cursor_h_
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#include "sql_class.h" /* Query_arena */
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class JOIN;
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/**
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@file
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Declarations for implementation of server side cursors. Only
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read-only non-scrollable cursors are currently implemented.
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*/
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/**
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Server_side_cursor -- an interface for materialized
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implementation of cursors. All cursors are self-contained
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(created in their own memory root). For that reason they must
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be deleted only using a pointer to Server_side_cursor, not to
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its base class.
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*/
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class Server_side_cursor: protected Query_arena
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{
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protected:
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/** Row destination used for fetch */
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select_result *result;
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public:
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Server_side_cursor(MEM_ROOT *mem_root_arg, select_result *result_arg)
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:Query_arena(mem_root_arg, STMT_INITIALIZED), result(result_arg)
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{}
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virtual bool is_open() const= 0;
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virtual int open(JOIN *top_level_join)= 0;
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virtual void fetch(ulong num_rows)= 0;
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virtual void close()= 0;
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virtual bool export_structure(THD *thd, Row_definition_list *defs)
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{
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DBUG_ASSERT(0);
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return true;
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}
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virtual ~Server_side_cursor();
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static void *operator new(size_t size, MEM_ROOT *mem_root)
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{ return alloc_root(mem_root, size); }
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static void operator delete(void *ptr, size_t size);
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static void operator delete(void *, MEM_ROOT *){}
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};
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/**
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Materialized_cursor -- an insensitive materialized server-side
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cursor. The result set of this cursor is saved in a temporary
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table at open. The cursor itself is simply an interface for the
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handler of the temporary table.
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*/
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class Materialized_cursor: public Server_side_cursor
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{
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MEM_ROOT main_mem_root;
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/* A fake unit to supply to select_send when fetching */
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SELECT_LEX_UNIT fake_unit;
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TABLE *table;
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List<Item> item_list;
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ulong fetch_limit;
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ulong fetch_count;
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bool is_rnd_inited;
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public:
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Materialized_cursor(select_result *result, TABLE *table);
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int send_result_set_metadata(THD *thd, List<Item> &send_result_set_metadata);
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bool is_open() const override { return table != 0; }
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int open(JOIN *join __attribute__((unused))) override;
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void fetch(ulong num_rows) override;
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void close() override;
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bool export_structure(THD *thd, Row_definition_list *defs) override
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{
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return table->export_structure(thd, defs);
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}
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~Materialized_cursor() override;
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void on_table_fill_finished();
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};
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/**
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Select_materialize -- a mediator between a cursor query and the
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protocol. In case we were not able to open a non-materialzed
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cursor, it creates an internal temporary HEAP table, and insert
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all rows into it. When the table reaches max_heap_table_size,
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it's converted to a MyISAM table. Later this table is used to
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create a Materialized_cursor.
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*/
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class Select_materialize: public select_unit
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{
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select_result *result; /**< the result object of the caller (PS or SP) */
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public:
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Materialized_cursor *materialized_cursor;
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Select_materialize(THD *thd_arg, select_result *result_arg):
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select_unit(thd_arg), result(result_arg), materialized_cursor(0) {}
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bool send_result_set_metadata(List<Item> &list, uint flags) override;
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bool send_eof() override { return false; }
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bool view_structure_only() const override
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{
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return result->view_structure_only();
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}
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};
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int mysql_open_cursor(THD *thd, select_result *result,
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Server_side_cursor **res);
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#endif /* _sql_cusor_h_ */
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