sql_derived.cc 8.3 KB
Newer Older
1
/* Copyright (C) 2002-2003 MySQL AB
unknown's avatar
unknown committed
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

   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; either version 2 of the License, or
   (at your option) any later version.

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


/*
  Derived tables
20
  These were introduced by Sinisa <sinisa@mysql.com>
unknown's avatar
unknown committed
21 22 23 24 25 26
*/


#include "mysql_priv.h"
#include "sql_select.h"

unknown's avatar
unknown committed
27

28 29

/*
30
  Call given derived table processor (preparing or filling tables)
31 32 33 34

  SYNOPSIS
    mysql_handle_derived()
    lex                 LEX for this thread
unknown's avatar
unknown committed
35
    processor           procedure of derived table processing
36 37

  RETURN
38 39
    FALSE  OK
    TRUE   Error
40
*/
unknown's avatar
unknown committed
41

42 43
bool
mysql_handle_derived(LEX *lex, bool (*processor)(THD*, LEX*, TABLE_LIST*))
44
{
45
  bool res= FALSE;
46 47
  if (lex->derived_tables)
  {
48
    lex->thd->derived_tables_processing= TRUE;
49 50 51 52 53 54
    for (SELECT_LEX *sl= lex->all_selects_list;
	 sl;
	 sl= sl->next_select_in_list())
    {
      for (TABLE_LIST *cursor= sl->get_table_list();
	   cursor;
unknown's avatar
VIEW  
unknown committed
55
	   cursor= cursor->next_local)
56
      {
unknown's avatar
unknown committed
57
	if ((res= (*processor)(lex->thd, lex, cursor)))
58
	  goto out;
59
      }
60 61 62 63 64 65 66 67 68
      if (lex->describe)
      {
	/*
	  Force join->join_tmp creation, because we will use this JOIN
	  twice for EXPLAIN and we have to have unchanged join for EXPLAINing
	*/
	sl->uncacheable|= UNCACHEABLE_EXPLAIN;
	sl->master_unit()->uncacheable|= UNCACHEABLE_EXPLAIN;
      }
69 70
    }
  }
71 72 73
out:
  lex->thd->derived_tables_processing= FALSE;
  return res;
74 75 76
}


77
/*
unknown's avatar
unknown committed
78
  Create temporary table structure (but do not fill it)
79 80

  SYNOPSIS
unknown's avatar
unknown committed
81
    mysql_derived_prepare()
82 83
    thd			Thread handle
    lex                 LEX for this thread
unknown's avatar
unknown committed
84
    orig_table_list     TABLE_LIST for the upper SELECT
85 86

  IMPLEMENTATION
unknown's avatar
unknown committed
87
    Derived table is resolved with temporary table.
88 89

    After table creation, the above TABLE_LIST is updated with a new table.
90

91 92
    This function is called before any command containing derived table
    is executed.
93

94 95
    Derived tables is stored in thd->derived_tables and freed in
    close_thread_tables()
96

97
  RETURN
98 99
    FALSE  OK
    TRUE   Error
100
*/
unknown's avatar
unknown committed
101

102
bool mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
unknown's avatar
unknown committed
103
{
unknown's avatar
unknown committed
104
  SELECT_LEX_UNIT *unit= orig_table_list->derived;
105
  ulonglong create_options;
unknown's avatar
unknown committed
106
  DBUG_ENTER("mysql_derived_prepare");
107
  bool res= FALSE;
unknown's avatar
unknown committed
108
  if (unit)
unknown's avatar
unknown committed
109
  {
unknown's avatar
unknown committed
110 111 112 113 114 115
    SELECT_LEX *first_select= unit->first_select();
    TABLE *table= 0;
    select_union *derived_result;
    bool is_union= first_select->next_select() && 
      first_select->next_select()->linkage == UNION_TYPE;

116 117 118 119
    /* prevent name resolving out of derived table */
    for (SELECT_LEX *sl= first_select; sl; sl= sl->next_select())
      sl->context.outer_context= 0;

120
    if (!(derived_result= new select_union))
121
      DBUG_RETURN(TRUE); // out of memory
unknown's avatar
unknown committed
122 123

    // st_select_lex_unit::prepare correctly work for single select
124
    if ((res= unit->prepare(thd, derived_result, 0)))
unknown's avatar
unknown committed
125 126
      goto exit;

127
    if ((res= check_duplicate_names(unit->types, 0)))
128
      goto exit;
unknown's avatar
unknown committed
129

130 131
    create_options= (first_select->options | thd->options |
                     TMP_TABLE_ALL_COLUMNS);
unknown's avatar
unknown committed
132 133 134
    /*
      Temp table is created so that it hounours if UNION without ALL is to be 
      processed
unknown's avatar
unknown committed
135 136 137 138 139 140

      As 'distinct' parameter we always pass FALSE (0), because underlying
      query will control distinct condition by itself. Correct test of
      distinct underlying query will be is_union &&
      !unit->union_distinct->next_select() (i.e. it is union and last distinct
      SELECT is last SELECT of UNION).
unknown's avatar
unknown committed
141
    */
142 143 144
    if ((res= derived_result->create_result_table(thd, &unit->types, FALSE,
                                                 create_options,
                                                 orig_table_list->alias)))
unknown's avatar
unknown committed
145
      goto exit;
146 147

    table= derived_result->table;
unknown's avatar
unknown committed
148 149

exit:
150 151 152 153 154 155 156 157
    /* Hide "Unknown column" or "Unknown function" error */
    if (orig_table_list->view)
    {
      if (thd->net.last_errno == ER_BAD_FIELD_ERROR ||
          thd->net.last_errno == ER_SP_DOES_NOT_EXIST)
      {
        thd->clear_error();
        my_error(ER_VIEW_INVALID, MYF(0), orig_table_list->db,
158
                 orig_table_list->table_name);
159 160 161
      }
    }

unknown's avatar
unknown committed
162 163 164 165 166 167 168 169 170 171 172 173 174 175
    /*
      if it is preparation PS only or commands that need only VIEW structure
      then we do not need real data and we can skip execution (and parameters
      is not defined, too)
    */
    if (res)
    {
      if (table)
	free_tmp_table(thd, table);
      delete derived_result;
    }
    else
    {
      if (!thd->fill_derived_tables())
176
      {
unknown's avatar
unknown committed
177
	delete derived_result;
178 179
	derived_result= NULL;
      }
unknown's avatar
unknown committed
180 181
      orig_table_list->derived_result= derived_result;
      orig_table_list->table= table;
182
      orig_table_list->table_name= (char*) table->s->table_name;
183
      orig_table_list->table_name_length= strlen((char*)table->s->table_name);
unknown's avatar
unknown committed
184
      table->derived_select_number= first_select->select_number;
185
      table->s->tmp_table= TMP_TABLE;
unknown's avatar
unknown committed
186
#ifndef NO_EMBEDDED_ACCESS_CHECKS
187 188 189 190
      if (orig_table_list->referencing_view)
        table->grant= orig_table_list->grant;
      else
        table->grant.privilege= SELECT_ACL;
unknown's avatar
unknown committed
191 192
#endif
      orig_table_list->db= (char *)"";
193
      orig_table_list->db_length= 0;
unknown's avatar
unknown committed
194 195 196 197 198 199
      // Force read of table stats in the optimizer
      table->file->info(HA_STATUS_VARIABLE);
      /* Add new temporary table to list of open derived tables */
      table->next= thd->derived_tables;
      thd->derived_tables= table;
    }
200
  }
201 202
  else if (orig_table_list->merge_underlying_list)
    orig_table_list->set_underlying_merge();
unknown's avatar
unknown committed
203
  DBUG_RETURN(res);
unknown's avatar
unknown committed
204 205
}

206

unknown's avatar
unknown committed
207 208 209 210 211 212 213 214 215 216 217 218 219 220 221
/*
  fill derived table

  SYNOPSIS
    mysql_derived_filling()
    thd			Thread handle
    lex                 LEX for this thread
    unit                node that contains all SELECT's for derived tables
    orig_table_list     TABLE_LIST for the upper SELECT

  IMPLEMENTATION
    Derived table is resolved with temporary table. It is created based on the
    queries defined. After temporary table is filled, if this is not EXPLAIN,
    then the entire unit / node is deleted. unit is deleted if UNION is used
    for derived table and node is deleted is it is a  simple SELECT.
222 223
    If you use this function, make sure it's not called at prepare.
    Due to evaluation of LIMIT clause it can not be used at prepared stage.
unknown's avatar
unknown committed
224 225

  RETURN
226 227
    FALSE  OK
    TRUE   Error
228
*/
unknown's avatar
unknown committed
229

230
bool mysql_derived_filling(THD *thd, LEX *lex, TABLE_LIST *orig_table_list)
unknown's avatar
unknown committed
231 232 233
{
  TABLE *table= orig_table_list->table;
  SELECT_LEX_UNIT *unit= orig_table_list->derived;
234
  bool res= FALSE;
unknown's avatar
unknown committed
235 236 237

  /*check that table creation pass without problem and it is derived table */
  if (table && unit)
238
  {
unknown's avatar
unknown committed
239 240 241 242 243
    SELECT_LEX *first_select= unit->first_select();
    select_union *derived_result= orig_table_list->derived_result;
    SELECT_LEX *save_current_select= lex->current_select;
    bool is_union= first_select->next_select() &&
      first_select->next_select()->linkage == UNION_TYPE;
244 245 246
    if (is_union)
    {
      // execute union without clean up
unknown's avatar
unknown committed
247
      res= unit->exec();
248 249 250
    }
    else
    {
251
      unit->set_limit(first_select);
252 253 254 255
      if (unit->select_limit_cnt == HA_POS_ERROR)
	first_select->options&= ~OPTION_FOUND_ROWS;

      lex->current_select= first_select;
unknown's avatar
unknown committed
256
      res= mysql_select(thd, &first_select->ref_pointer_array,
257 258 259 260 261 262 263 264 265 266 267 268
			(TABLE_LIST*) first_select->table_list.first,
			first_select->with_wild,
			first_select->item_list, first_select->where,
			(first_select->order_list.elements+
			 first_select->group_list.elements),
			(ORDER *) first_select->order_list.first,
			(ORDER *) first_select->group_list.first,
			first_select->having, (ORDER*) NULL,
			(first_select->options | thd->options |
			 SELECT_NO_UNLOCK),
			derived_result, unit, first_select);
    }
unknown's avatar
unknown committed
269

unknown's avatar
unknown committed
270
    if (!res)
271
    {
unknown's avatar
unknown committed
272 273 274 275 276
      /*
        Here we entirely fix both TABLE_LIST and list of SELECT's as
        there were no derived tables
      */
      if (derived_result->flush())
277
        res= TRUE;
278

unknown's avatar
unknown committed
279 280 281
      if (!lex->describe)
        unit->cleanup();
    }
282
    else
unknown's avatar
unknown committed
283 284
      unit->cleanup();
    lex->current_select= save_current_select;
unknown's avatar
unknown committed
285
  }
unknown's avatar
unknown committed
286
  return res;
unknown's avatar
unknown committed
287
}