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MySQL 5.1: Materialized_cursor Class Reference

Materialized_cursor Class Reference

Inheritance diagram for Materialized_cursor:

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Public Member Functions
	Materialized_cursor (select_result result, TABLE table)
virtual bool	is_open () const
virtual int	open (JOIN *join __attribute__((unused)))
virtual void	fetch (ulong num_rows)
virtual void	close ()
virtual	~Materialized_cursor ()
Private Attributes
MEM_ROOT	main_mem_root
SELECT_LEX_UNIT	fake_unit
TABLE *	table
List< Item >	item_list
ulong	fetch_limit
ulong	fetch_count

Detailed Description

Definition at line 80 of file sql_cursor.cc.

Constructor & Destructor Documentation

Materialized_cursor::Materialized_cursor	(	select_result *	result,
		TABLE *	table
	)

Definition at line 536 of file sql_cursor.cc.

References fake_unit, st_table::in_use, and table.

00538   :Server_side_cursor(&table_arg->mem_root, result_arg),
00539   table(table_arg),
00540   fetch_limit(0),
00541   fetch_count(0)
00542 {
00543   fake_unit.init_query();
00544   fake_unit.thd= table->in_use;
00545 }

Materialized_cursor::~Materialized_cursor ( ) [virtual]

Definition at line 651 of file sql_cursor.cc.

References close(), and is_open().

00652 {
00653   if (is_open())
00654     close();
00655 }

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Member Function Documentation

void Materialized_cursor::close ( ) [virtual]

Implements Server_side_cursor.

Definition at line 634 of file sql_cursor.cc.

References clear_alloc_root, st_table::file, free_items(), free_tmp_table(), handler::ha_rnd_end(), st_table::in_use, main_mem_root, st_table::mem_root, and table.

Referenced by fetch(), and ~Materialized_cursor().

00635 {
00636   /* Free item_list items */
00637   free_items();
00638   (void) table->file->ha_rnd_end();
00639   /*
00640     We need to grab table->mem_root to prevent free_tmp_table from freeing:
00641     the cursor object was allocated in this memory.
00642   */
00643   main_mem_root= table->mem_root;
00644   mem_root= &main_mem_root;
00645   clear_alloc_root(&table->mem_root);
00646   free_tmp_table(table->in_use, table);
00647   table= 0;
00648 }

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void Materialized_cursor::fetch ( ulong num_rows ) [virtual]

Implements Server_side_cursor.

Definition at line 600 of file sql_cursor.cc.

References close(), fetch_count, fetch_limit, st_table::file, HA_ERR_END_OF_FILE, st_table::in_use, item_list, MYF, handler::print_error(), st_table::record, Server_side_cursor::result, handler::rnd_next(), SERVER_STATUS_CURSOR_EXISTS, SERVER_STATUS_LAST_ROW_SENT, and table.

00601 {
00602   THD *thd= table->in_use;
00603 
00604   int res= 0;
00605   result->begin_dataset();
00606   for (fetch_limit+= num_rows; fetch_count < fetch_limit; fetch_count++)
00607   {
00608     if ((res= table->file->rnd_next(table->record[0])))
00609       break;
00610     /* Send data only if the read was successful. */
00611     result->send_data(item_list);
00612   }
00613 
00614   switch (res) {
00615   case 0:
00616     thd->server_status|= SERVER_STATUS_CURSOR_EXISTS;
00617     result->send_eof();
00618     thd->server_status&= ~SERVER_STATUS_CURSOR_EXISTS;
00619     break;
00620   case HA_ERR_END_OF_FILE:
00621     thd->server_status|= SERVER_STATUS_LAST_ROW_SENT;
00622     result->send_eof();
00623     thd->server_status&= ~SERVER_STATUS_LAST_ROW_SENT;
00624     close();
00625     break;
00626   default:
00627     table->file->print_error(res, MYF(0));
00628     close();
00629     break;
00630   }
00631 }

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virtual bool Materialized_cursor::is_open ( ) const [inline, virtual]

Implements Server_side_cursor.

Definition at line 92 of file sql_cursor.cc.

References table.

Referenced by ~Materialized_cursor().

00092 { return table != 0; }

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int Materialized_cursor::open ( JOIN *join __attribute__((unused)) ) [virtual]

Definition at line 548 of file sql_cursor.cc.

References fake_unit, st_table::file, st_table::fill_item_list(), handler::ha_rnd_init(), item_list, Server_side_cursor::result, Protocol::SEND_NUM_ROWS, SERVER_STATUS_CURSOR_EXISTS, table, and TRUE.

Referenced by mysql_open_cursor().

00549 {
00550   THD *thd= fake_unit.thd;
00551   int rc;
00552   Query_arena backup_arena;
00553 
00554   thd->set_n_backup_active_arena(this, &backup_arena);
00555   /* Create a list of fields and start sequential scan */
00556   rc= (table->fill_item_list(&item_list) ||
00557        result->prepare(item_list, &fake_unit) ||
00558        table->file->ha_rnd_init(TRUE));
00559   thd->restore_active_arena(this, &backup_arena);
00560   if (rc == 0)
00561   {
00562     /*
00563       Now send the result set metadata to the client. We need to
00564       do it here, as in Select_materialize::send_fields the items
00565       for column types are not yet created (send_fields requires
00566       a list of items). The new types may differ from the original
00567       ones sent at prepare if some of them were altered by MySQL
00568       HEAP tables mechanism -- used when create_tmp_field_from_item
00569       may alter the original column type.
00570 
00571       We can't simply supply SEND_EOF flag to send_fields, because
00572       send_fields doesn't flush the network buffer.
00573     */
00574     rc= result->send_fields(item_list, Protocol::SEND_NUM_ROWS);
00575     thd->server_status|= SERVER_STATUS_CURSOR_EXISTS;
00576     result->send_eof();
00577     thd->server_status&= ~SERVER_STATUS_CURSOR_EXISTS;
00578   }
00579   return rc;
00580 }