mysql-innodb_dict_size_limit.patch

   1 diff -ruN a/innobase/btr/btr0sea.c b/innobase/btr/btr0sea.c
   2 --- a/innobase/btr/btr0sea.c    2009-08-27 18:42:17.000000000 +0900
   3 +++ b/innobase/btr/btr0sea.c    2009-08-27 18:43:11.000000000 +0900
   4 @@ -1077,6 +1077,124 @@
   5  }
   6
   7  /************************************************************************
   8 +Drops a page hash index based on index */
   9 +
  10 +void
  11 +btr_search_drop_page_hash_index_on_index(
  12 +/*=====================================*/
  13 +       dict_index_t*   index)          /* in: record descriptor */
  14 +{
  15 +       page_t*         page;
  16 +       hash_table_t*   table;
  17 +       buf_block_t*    block;
  18 +       ulint           n_fields;
  19 +       ulint           n_bytes;
  20 +       rec_t*          rec;
  21 +       ulint           fold;
  22 +       ulint           prev_fold;
  23 +       dulint          tree_id;
  24 +       ulint           n_cached;
  25 +       ulint           n_recs;
  26 +       ulint*          folds;
  27 +       ulint           i;
  28 +       mem_heap_t*     heap    = NULL;
  29 +       ulint*          offsets;
  30 +
  31 +       rw_lock_x_lock(&btr_search_latch);
  32 +       mutex_enter(&buf_pool->mutex);
  33 +
  34 +       table = btr_search_sys->hash_index;
  35 +
  36 +       block = UT_LIST_GET_LAST(buf_pool->LRU);
  37 +
  38 +       while (block != NULL) {
  39 +               if (block->index == index && block->is_hashed) {
  40 +                       page = block->frame;
  41 +
  42 +                       /* from btr_search_drop_page_hash_index() */
  43 +                       n_fields = block->curr_n_fields;
  44 +                       n_bytes = block->curr_n_bytes;
  45 +
  46 +                       ut_a(n_fields + n_bytes > 0);
  47 +
  48 +                       n_recs = page_get_n_recs(page);
  49 +
  50 +                       /* Calculate and cache fold values into an array for fast deletion
  51 +                       from the hash index */
  52 +
  53 +                       folds = mem_alloc(n_recs * sizeof(ulint));
  54 +
  55 +                       n_cached = 0;
  56 +
  57 +                       rec = page_get_infimum_rec(page);
  58 +                       rec = page_rec_get_next(rec);
  59 +
  60 +                       tree_id = btr_page_get_index_id(page);
  61 +
  62 +                       ut_a(0 == ut_dulint_cmp(tree_id, index->id));
  63 +
  64 +                       prev_fold = 0;
  65 +
  66 +                       offsets = NULL;
  67 +
  68 +                       while (!page_rec_is_supremum(rec)) {
  69 +                               /* FIXME: in a mixed tree, not all records may have enough
  70 +                               ordering fields: */
  71 +                               offsets = rec_get_offsets(rec, index, offsets,
  72 +                                                       n_fields + (n_bytes > 0), &heap);
  73 +                               ut_a(rec_offs_n_fields(offsets) == n_fields + (n_bytes > 0));
  74 +                               fold = rec_fold(rec, offsets, n_fields, n_bytes, tree_id);
  75 +
  76 +                               if (fold == prev_fold && prev_fold != 0) {
  77 +
  78 +                                       goto next_rec;
  79 +                               }
  80 +
  81 +                               /* Remove all hash nodes pointing to this page from the
  82 +                               hash chain */
  83 +
  84 +                               folds[n_cached] = fold;
  85 +                               n_cached++;
  86 +next_rec:
  87 +                               rec = page_rec_get_next(rec);
  88 +                               prev_fold = fold;
  89 +                       }
  90 +
  91 +                       for (i = 0; i < n_cached; i++) {
  92 +
  93 +                               ha_remove_all_nodes_to_page(table, folds[i], page);
  94 +                       }
  95 +
  96 +                       ut_a(index->search_info->ref_count > 0);
  97 +                       index->search_info->ref_count--;
  98 +
  99 +                       block->is_hashed = FALSE;
 100 +                       block->index = NULL;
 101 +
 102 +                       if (UNIV_UNLIKELY(block->n_pointers)) {
 103 +                               /* Corruption */
 104 +                               ut_print_timestamp(stderr);
 105 +                               fprintf(stderr,
 106 +"  InnoDB: Corruption of adaptive hash index. After dropping\n"
 107 +"InnoDB: the hash index to a page of %s, still %lu hash nodes remain.\n",
 108 +                                       index->name, (ulong) block->n_pointers);
 109 +                       }
 110 +
 111 +                       mem_free(folds);
 112 +               }
 113 +
 114 +               block = UT_LIST_GET_PREV(LRU, block);
 115 +       }
 116 +
 117 +       mutex_exit(&buf_pool->mutex);
 118 +       rw_lock_x_unlock(&btr_search_latch);
 119 +
 120 +       if (UNIV_LIKELY_NULL(heap)) {
 121 +               mem_heap_free(heap);
 122 +       }
 123 +}
 124 +
 125 +/************************************************************************
 126  Drops a page hash index when a page is freed from a fseg to the file system.
 127  Drops possible hash index if the page happens to be in the buffer pool. */
 128
 129 diff -ruN a/innobase/dict/dict0boot.c b/innobase/dict/dict0boot.c
 130 --- a/innobase/dict/dict0boot.c 2009-07-07 21:53:58.000000000 +0900
 131 +++ b/innobase/dict/dict0boot.c 2009-08-27 18:42:59.000000000 +0900
 132 @@ -247,6 +247,7 @@
 133         system tables */
 134         /*-------------------------*/
 135         table = dict_mem_table_create("SYS_TABLES", DICT_HDR_SPACE, 8, FALSE);
 136 +       table->n_mysql_handles_opened = 1; /* for pin */
 137
 138         dict_mem_table_add_col(table, "NAME", DATA_BINARY, 0, 0, 0);
 139         dict_mem_table_add_col(table, "ID", DATA_BINARY, 0, 0, 0);
 140 @@ -283,6 +284,7 @@
 141         ut_a(success);
 142         /*-------------------------*/
 143         table = dict_mem_table_create("SYS_COLUMNS", DICT_HDR_SPACE, 7, FALSE);
 144 +       table->n_mysql_handles_opened = 1; /* for pin */
 145
 146         dict_mem_table_add_col(table, "TABLE_ID", DATA_BINARY,0,0,0);
 147         dict_mem_table_add_col(table, "POS", DATA_INT, 0, 4, 0);
 148 @@ -309,6 +311,7 @@
 149         ut_a(success);
 150         /*-------------------------*/
 151         table = dict_mem_table_create("SYS_INDEXES", DICT_HDR_SPACE, 7, FALSE);
 152 +       table->n_mysql_handles_opened = 1; /* for pin */
 153
 154         dict_mem_table_add_col(table, "TABLE_ID", DATA_BINARY, 0,0,0);
 155         dict_mem_table_add_col(table, "ID", DATA_BINARY, 0, 0, 0);
 156 @@ -345,6 +348,7 @@
 157         ut_a(success);
 158         /*-------------------------*/
 159         table = dict_mem_table_create("SYS_FIELDS", DICT_HDR_SPACE, 3, FALSE);
 160 +       table->n_mysql_handles_opened = 1; /* for pin */
 161
 162         dict_mem_table_add_col(table, "INDEX_ID", DATA_BINARY, 0,0,0);
 163         dict_mem_table_add_col(table, "POS", DATA_INT, 0, 4, 0);
 164 diff -ruN a/innobase/dict/dict0crea.c b/innobase/dict/dict0crea.c
 165 --- a/innobase/dict/dict0crea.c 2009-07-07 21:53:58.000000000 +0900
 166 +++ b/innobase/dict/dict0crea.c 2009-08-27 18:42:59.000000000 +0900
 167 @@ -1178,6 +1178,9 @@
 168                 /* Foreign constraint system tables have already been
 169                 created, and they are ok */
 170
 171 +               table1->n_mysql_handles_opened = 1; /* for pin */
 172 +               table2->n_mysql_handles_opened = 1; /* for pin */
 173 +
 174                 mutex_exit(&(dict_sys->mutex));
 175
 176                 return(DB_SUCCESS);
 177 @@ -1267,6 +1270,11 @@
 178
 179         trx->op_info = "";
 180
 181 +       table1 = dict_table_get_low("SYS_FOREIGN");
 182 +       table2 = dict_table_get_low("SYS_FOREIGN_COLS");
 183 +       table1->n_mysql_handles_opened = 1; /* for pin */
 184 +       table2->n_mysql_handles_opened = 1; /* for pin */
 185 +
 186         row_mysql_unlock_data_dictionary(trx);
 187
 188         trx_free_for_mysql(trx);
 189 diff -ruN a/innobase/dict/dict0dict.c b/innobase/dict/dict0dict.c
 190 --- a/innobase/dict/dict0dict.c 2009-07-07 21:53:58.000000000 +0900
 191 +++ b/innobase/dict/dict0dict.c 2009-08-27 18:43:11.000000000 +0900
 192 @@ -638,6 +638,8 @@
 193         mutex_enter(&(dict_sys->mutex));
 194
 195         table = dict_table_get_on_id_low(table_id, trx);
 196 +
 197 +       dict_table_LRU_trim(table);
 198
 199         mutex_exit(&(dict_sys->mutex));
 200
 201 @@ -752,6 +754,8 @@
 202
 203         table = dict_table_get_low(table_name);
 204
 205 +       dict_table_LRU_trim(table);
 206 +
 207         mutex_exit(&(dict_sys->mutex));
 208
 209         if (table != NULL) {
 210 @@ -787,6 +791,8 @@
 211                 table->n_mysql_handles_opened++;
 212         }
 213
 214 +       dict_table_LRU_trim(table);
 215 +
 216         mutex_exit(&(dict_sys->mutex));
 217
 218         if (table != NULL) {
 219 @@ -1267,20 +1273,64 @@
 220  too much space. Currently not used! */
 221
 222  void
 223 -dict_table_LRU_trim(void)
 224 -/*=====================*/
 225 +dict_table_LRU_trim(
 226 +/*================*/
 227 +       dict_table_t*   self)
 228  {
 229         dict_table_t*   table;
 230         dict_table_t*   prev_table;
 231 +       dict_foreign_t* foreign;
 232 +       ulint           n_removed;
 233 +       ulint           n_have_parent;
 234 +       ulint           cached_foreign_tables;
 235
 236 -       ut_error;
 237 +       //ut_error;
 238
 239  #ifdef UNIV_SYNC_DEBUG
 240         ut_ad(mutex_own(&(dict_sys->mutex)));
 241  #endif /* UNIV_SYNC_DEBUG */
 242
 243 +retry:
 244 +       n_removed = n_have_parent = 0;
 245         table = UT_LIST_GET_LAST(dict_sys->table_LRU);
 246
 247 +       while ( srv_dict_size_limit && table
 248 +               && ((dict_sys->table_hash->n_cells
 249 +                    + dict_sys->table_id_hash->n_cells
 250 +                    + dict_sys->col_hash->n_cells) * sizeof(hash_cell_t)
 251 +                   + dict_sys->size) > srv_dict_size_limit ) {
 252 +               prev_table = UT_LIST_GET_PREV(table_LRU, table);
 253 +
 254 +               if (table == self || table->n_mysql_handles_opened)
 255 +                       goto next_loop;
 256 +
 257 +               cached_foreign_tables = 0;
 258 +               foreign = UT_LIST_GET_FIRST(table->foreign_list);
 259 +               while (foreign != NULL) {
 260 +                       if (foreign->referenced_table)
 261 +                               cached_foreign_tables++;
 262 +                       foreign = UT_LIST_GET_NEXT(foreign_list, foreign);
 263 +               }
 264 +
 265 +               /* TODO: use table->mem_fix also, if it becomes exact. */
 266 +
 267 +               if (cached_foreign_tables == 0) {
 268 +                       dict_table_remove_from_cache(table);
 269 +                       n_removed++;
 270 +               } else {
 271 +                       n_have_parent++;
 272 +               }
 273 +next_loop:
 274 +               table = prev_table;
 275 +       }
 276 +
 277 +       if ( srv_dict_size_limit && n_have_parent && n_removed
 278 +               && ((dict_sys->table_hash->n_cells
 279 +                    + dict_sys->table_id_hash->n_cells
 280 +                    + dict_sys->col_hash->n_cells) * sizeof(hash_cell_t)
 281 +                   + dict_sys->size) > srv_dict_size_limit )
 282 +               goto retry;
 283 +/*
 284         while (table && (dict_sys->size >
 285                          buf_pool_get_max_size() / DICT_POOL_PER_VARYING)) {
 286
 287 @@ -1292,6 +1342,7 @@
 288
 289                 table = prev_table;
 290         }
 291 +*/
 292  }
 293
 294  /**************************************************************************
 295 @@ -1565,6 +1616,10 @@
 296  #ifdef UNIV_SYNC_DEBUG
 297         ut_ad(mutex_own(&(dict_sys->mutex)));
 298  #endif /* UNIV_SYNC_DEBUG */
 299 +       /* remove all entry of the index from adaptive hash index,
 300 +       because removing from adaptive hash index needs dict_index */
 301 +       if (srv_use_adaptive_hash_indexes && srv_dict_size_limit)
 302 +               btr_search_drop_page_hash_index_on_index(index);
 303
 304         /* We always create search info whether or not adaptive
 305         hash index is enabled or not. */
 306 diff -ruN a/innobase/ibuf/ibuf0ibuf.c b/innobase/ibuf/ibuf0ibuf.c
 307 --- a/innobase/ibuf/ibuf0ibuf.c 2009-08-27 18:42:17.000000000 +0900
 308 +++ b/innobase/ibuf/ibuf0ibuf.c 2009-08-27 18:42:59.000000000 +0900
 309 @@ -535,6 +535,7 @@
 310         sprintf(buf, "SYS_IBUF_TABLE_%lu", (ulong) space);
 311         /* use old-style record format for the insert buffer */
 312         table = dict_mem_table_create(buf, space, 2, FALSE);
 313 +       table->n_mysql_handles_opened = 1; /* for pin */
 314
 315         dict_mem_table_add_col(table, "PAGE_NO", DATA_BINARY, 0, 0, 0);
 316         dict_mem_table_add_col(table, "TYPES", DATA_BINARY, 0, 0, 0);
 317 diff -ruN a/innobase/include/btr0sea.h b/innobase/include/btr0sea.h
 318 --- a/innobase/include/btr0sea.h        2009-07-07 21:54:00.000000000 +0900
 319 +++ b/innobase/include/btr0sea.h        2009-08-27 18:43:11.000000000 +0900
 320 @@ -97,6 +97,13 @@
 321  /*============================*/
 322         page_t* page);  /* in: index page, s- or x-latched */
 323  /************************************************************************
 324 +Drops a page hash index based on index */
 325 +
 326 +void
 327 +btr_search_drop_page_hash_index_on_index(
 328 +/*=====================================*/
 329 +       dict_index_t*   index);         /* in: record descriptor */
 330 +/************************************************************************
 331  Drops a page hash index when a page is freed from a fseg to the file system.
 332  Drops possible hash index if the page happens to be in the buffer pool. */
 333
 334 diff -ruN a/innobase/include/dict0dict.h b/innobase/include/dict0dict.h
 335 --- a/innobase/include/dict0dict.h      2009-07-07 21:54:01.000000000 +0900
 336 +++ b/innobase/include/dict0dict.h      2009-08-27 18:42:59.000000000 +0900
 337 @@ -938,6 +938,11 @@
 338         const char*     ptr,    /* in: scan from */
 339         const char*     string);/* in: look for this */
 340
 341 +void
 342 +dict_table_LRU_trim(
 343 +/*================*/
 344 +       dict_table_t*   self);
 345 +
 346  /* Buffers for storing detailed information about the latest foreign key
 347  and unique key errors */
 348  extern FILE*   dict_foreign_err_file;
 349 diff -ruN a/innobase/include/dict0dict.ic b/innobase/include/dict0dict.ic
 350 --- a/innobase/include/dict0dict.ic     2009-07-07 21:54:01.000000000 +0900
 351 +++ b/innobase/include/dict0dict.ic     2009-08-27 18:42:59.000000000 +0900
 352 @@ -533,6 +533,13 @@
 353
 354         HASH_SEARCH(name_hash, dict_sys->table_hash, table_fold, table,
 355                                 ut_strcmp(table->name, table_name) == 0);
 356 +
 357 +       /* make young in table_LRU */
 358 +       if (table) {
 359 +               UT_LIST_REMOVE(table_LRU, dict_sys->table_LRU, table);
 360 +               UT_LIST_ADD_FIRST(table_LRU, dict_sys->table_LRU, table);
 361 +       }
 362 +
 363         return(table);
 364  }
 365
 366 @@ -592,6 +599,10 @@
 367         if (table != NULL) {
 368                 table->mem_fix++;
 369
 370 +               /* make young in table_LRU */
 371 +               UT_LIST_REMOVE(table_LRU, dict_sys->table_LRU, table);
 372 +               UT_LIST_ADD_FIRST(table_LRU, dict_sys->table_LRU, table);
 373 +
 374                 /* lock_push(trx, table, LOCK_DICT_MEM_FIX) */
 375         }
 376
 377 diff -ruN a/innobase/include/srv0srv.h b/innobase/include/srv0srv.h
 378 --- a/innobase/include/srv0srv.h        2009-08-27 18:42:17.000000000 +0900
 379 +++ b/innobase/include/srv0srv.h        2009-08-27 18:42:59.000000000 +0900
 380 @@ -147,6 +147,8 @@
 381  extern uint    srv_read_ahead;
 382  extern uint    srv_adaptive_checkpoint;
 383
 384 +extern ulint   srv_dict_size_limit;
 385 +
 386  extern volatile ibool srv_io_pattern;
 387  extern ulong   srv_io_pattern_trace;
 388  extern ulong   srv_io_pattern_trace_running;
 389 @@ -552,6 +554,7 @@
 390          ulint innodb_data_writes;
 391          ulint innodb_data_written;
 392          ulint innodb_data_reads;
 393 +        ulint innodb_dict_tables;
 394          ulint innodb_buffer_pool_pages_total;
 395          ulint innodb_buffer_pool_pages_data;
 396          ulint innodb_buffer_pool_pages_dirty;
 397 diff -ruN a/innobase/srv/srv0srv.c b/innobase/srv/srv0srv.c
 398 --- a/innobase/srv/srv0srv.c    2009-08-27 18:42:17.000000000 +0900
 399 +++ b/innobase/srv/srv0srv.c    2009-08-27 18:42:59.000000000 +0900
 400 @@ -353,6 +353,8 @@
 401  uint   srv_read_ahead = 3; /* 1: random  2: linear  3: Both */
 402  uint   srv_adaptive_checkpoint = 0; /* 0: none  1: reflex  2: estimate */
 403
 404 +ulint  srv_dict_size_limit = 0;
 405 +
 406  volatile ibool srv_io_pattern = FALSE;
 407  ulint   srv_io_pattern_trace = 0;
 408  ulint   srv_io_pattern_trace_running = 0;
 409 @@ -1953,6 +1955,7 @@
 410          export_vars.innodb_data_reads= os_n_file_reads;
 411          export_vars.innodb_data_writes= os_n_file_writes;
 412          export_vars.innodb_data_written= srv_data_written;
 413 +        export_vars.innodb_dict_tables= (dict_sys ? UT_LIST_GET_LEN(dict_sys->table_LRU) : 0);
 414          export_vars.innodb_buffer_pool_read_requests= buf_pool->n_page_gets;
 415          export_vars.innodb_buffer_pool_write_requests= srv_buf_pool_write_requests;
 416          export_vars.innodb_buffer_pool_wait_free= srv_buf_pool_wait_free;
 417 diff -ruN a/mysql-test/r/innodb_dict_size_limit.result b/mysql-test/r/innodb_dict_size_limit.result
 418 --- /dev/null   1970-01-01 09:00:00.000000000 +0900
 419 +++ b/mysql-test/r/innodb_dict_size_limit.result        2009-08-27 18:42:59.000000000 +0900
 420 @@ -0,0 +1,60 @@
 421 +DROP TABLE IF EXISTS `test_5`;
 422 +DROP TABLE IF EXISTS `test_4`;
 423 +DROP TABLE IF EXISTS `test_3`;
 424 +DROP TABLE IF EXISTS `test_2`;
 425 +DROP TABLE IF EXISTS `test_1`;
 426 +SET storage_engine=InnoDB;
 427 +SET GLOBAL innodb_dict_size_limit=1;
 428 +FLUSH TABLES;
 429 +CREATE TABLE `test_1` (`a` int, `b` int, PRIMARY KEY  (`a`));
 430 +CREATE TABLE `test_2` (`a` int, `b` int, PRIMARY KEY  (`a`));
 431 +CREATE TABLE `test_3` (`a` int, `b` int, PRIMARY KEY  (`a`));
 432 +CREATE TABLE `test_4` (`a` int, `b` int, PRIMARY KEY  (`a`));
 433 +CREATE TABLE `test_5` (`a` int, `b` int, PRIMARY KEY  (`a`));
 434 +ALTER TABLE `test_5` ADD CONSTRAINT FOREIGN KEY(`b`) REFERENCES `test_4`(`a`);
 435 +ALTER TABLE `test_4` ADD CONSTRAINT FOREIGN KEY(`b`) REFERENCES `test_3`(`a`);
 436 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 437 +Variable_name  Value
 438 +Innodb_dict_tables     9
 439 +FLUSH TABLES;
 440 +SELECT * FROM `test_1`;
 441 +a      b
 442 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 443 +Variable_name  Value
 444 +Innodb_dict_tables     8
 445 +SELECT * FROM `test_3`;
 446 +a      b
 447 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 448 +Variable_name  Value
 449 +Innodb_dict_tables     11
 450 +FLUSH TABLES;
 451 +SELECT * FROM `test_2`;
 452 +a      b
 453 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 454 +Variable_name  Value
 455 +Innodb_dict_tables     8
 456 +SELECT * FROM `test_1`;
 457 +a      b
 458 +FLUSH TABLES;
 459 +SELECT * FROM `test_4`;
 460 +a      b
 461 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 462 +Variable_name  Value
 463 +Innodb_dict_tables     9
 464 +SELECT * FROM `test_3`;
 465 +a      b
 466 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 467 +Variable_name  Value
 468 +Innodb_dict_tables     10
 469 +SET GLOBAL innodb_dict_size_limit=0;
 470 +FLUSH TABLES;
 471 +SELECT * FROM `test_2`;
 472 +a      b
 473 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 474 +Variable_name  Value
 475 +Innodb_dict_tables     11
 476 +DROP TABLE `test_5`;
 477 +DROP TABLE `test_4`;
 478 +DROP TABLE `test_3`;
 479 +DROP TABLE `test_2`;
 480 +DROP TABLE `test_1`;
 481 diff -ruN a/mysql-test/t/innodb_dict_size_limit.test b/mysql-test/t/innodb_dict_size_limit.test
 482 --- /dev/null   1970-01-01 09:00:00.000000000 +0900
 483 +++ b/mysql-test/t/innodb_dict_size_limit.test  2009-08-27 18:42:59.000000000 +0900
 484 @@ -0,0 +1,63 @@
 485 +#
 486 +# Test for new variable innodb_dict_size_limit;
 487 +#
 488 +-- source include/have_innodb.inc
 489 +
 490 +--disable_warnings
 491 +DROP TABLE IF EXISTS `test_5`;
 492 +DROP TABLE IF EXISTS `test_4`;
 493 +DROP TABLE IF EXISTS `test_3`;
 494 +DROP TABLE IF EXISTS `test_2`;
 495 +DROP TABLE IF EXISTS `test_1`;
 496 +--enable_warnings
 497 +
 498 +SET storage_engine=InnoDB;
 499 +SET GLOBAL innodb_dict_size_limit=1;
 500 +
 501 +FLUSH TABLES;
 502 +
 503 +CREATE TABLE `test_1` (`a` int, `b` int, PRIMARY KEY  (`a`));
 504 +CREATE TABLE `test_2` (`a` int, `b` int, PRIMARY KEY  (`a`));
 505 +CREATE TABLE `test_3` (`a` int, `b` int, PRIMARY KEY  (`a`));
 506 +CREATE TABLE `test_4` (`a` int, `b` int, PRIMARY KEY  (`a`));
 507 +CREATE TABLE `test_5` (`a` int, `b` int, PRIMARY KEY  (`a`));
 508 +
 509 +ALTER TABLE `test_5` ADD CONSTRAINT FOREIGN KEY(`b`) REFERENCES `test_4`(`a`);
 510 +ALTER TABLE `test_4` ADD CONSTRAINT FOREIGN KEY(`b`) REFERENCES `test_3`(`a`);
 511 +
 512 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 513 +
 514 +FLUSH TABLES;
 515 +SELECT * FROM `test_1`;
 516 +
 517 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 518 +
 519 +SELECT * FROM `test_3`;
 520 +
 521 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 522 +
 523 +FLUSH TABLES;
 524 +SELECT * FROM `test_2`;
 525 +
 526 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 527 +
 528 +SELECT * FROM `test_1`;
 529 +FLUSH TABLES;
 530 +SELECT * FROM `test_4`;
 531 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 532 +
 533 +SELECT * FROM `test_3`;
 534 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 535 +
 536 +SET GLOBAL innodb_dict_size_limit=0;
 537 +FLUSH TABLES;
 538 +SELECT * FROM `test_2`;
 539 +
 540 +SHOW GLOBAL STATUS LIKE 'Innodb_dict_tables';
 541 +
 542 +DROP TABLE `test_5`;
 543 +DROP TABLE `test_4`;
 544 +DROP TABLE `test_3`;
 545 +DROP TABLE `test_2`;
 546 +DROP TABLE `test_1`;
 547 +
 548 diff -ruN a/patch_info/innodb_dict_size_limit.info b/patch_info/innodb_dict_size_limit.info
 549 --- /dev/null   1970-01-01 09:00:00.000000000 +0900
 550 +++ b/patch_info/innodb_dict_size_limit.info    2009-08-27 18:42:59.000000000 +0900
 551 @@ -0,0 +1,9 @@
 552 +File=innodb_dict_size_limit.patch
 553 +Name=Limit dictionary cache size
 554 +Version=1.0
 555 +Author=Percona
 556 +License=GPL
 557 +Comment=Variable innodb_dict_size_limit in bytes
 558 +ChangeLog=
 559 +2009-01-26
 560 +YK: Initial release
 561 diff -ruN a/sql/ha_innodb.cc b/sql/ha_innodb.cc
 562 --- a/sql/ha_innodb.cc  2009-08-27 18:42:17.000000000 +0900
 563 +++ b/sql/ha_innodb.cc  2009-08-27 18:42:59.000000000 +0900
 564 @@ -288,6 +288,8 @@
 565    (char*) &export_vars.innodb_dblwr_pages_written,        SHOW_LONG},
 566    {"dblwr_writes",
 567    (char*) &export_vars.innodb_dblwr_writes,               SHOW_LONG},
 568 +  {"dict_tables",
 569 +  (char*) &export_vars.innodb_dict_tables,                SHOW_LONG},
 570    {"log_waits",
 571    (char*) &export_vars.innodb_log_waits,                  SHOW_LONG},
 572    {"log_write_requests",
 573 diff -ruN a/sql/ha_innodb.h b/sql/ha_innodb.h
 574 --- a/sql/ha_innodb.h   2009-08-27 18:42:17.000000000 +0900
 575 +++ b/sql/ha_innodb.h   2009-08-27 18:42:59.000000000 +0900
 576 @@ -243,6 +243,7 @@
 577  extern ulong srv_enable_unsafe_group_commit;
 578  extern uint srv_read_ahead;
 579  extern uint srv_adaptive_checkpoint;
 580 +extern ulong srv_dict_size_limit;
 581  extern ulong srv_show_locks_held;
 582  extern ulong srv_show_verbose_locks;
 583  extern ulong srv_io_pattern_trace;
 584 diff -ruN a/sql/mysqld.cc b/sql/mysqld.cc
 585 --- a/sql/mysqld.cc     2009-08-27 18:42:17.000000000 +0900
 586 +++ b/sql/mysqld.cc     2009-08-27 18:42:59.000000000 +0900
 587 @@ -5101,6 +5101,7 @@
 588    OPT_INNODB_ADAPTIVE_CHECKPOINT,
 589    OPT_INNODB_READ_IO_THREADS,
 590    OPT_INNODB_WRITE_IO_THREADS,
 591 +  OPT_INNODB_DICT_SIZE_LIMIT,
 592    OPT_INNODB_ADAPTIVE_HASH_INDEX,
 593    OPT_FEDERATED,
 594    OPT_INNODB_USE_LEGACY_CARDINALITY_ALGORITHM
 595 @@ -5464,6 +5465,10 @@
 596     "Number of background write I/O threads in InnoDB.",
 597     (gptr*) &innobase_write_io_threads, (gptr*) &innobase_write_io_threads,
 598     0, GET_LONG, REQUIRED_ARG, 8, 1, 64, 0, 0, 0},
 599 +  {"innodb_dict_size_limit", OPT_INNODB_DICT_SIZE_LIMIT,
 600 +   "Limit the allocated memory for dictionary cache. (0: unlimited)",
 601 +   (gptr*) &srv_dict_size_limit, (gptr*) &srv_dict_size_limit, 0,
 602 +   GET_ULONG, REQUIRED_ARG, 0, 0, ULONG_MAX, 0, 0 ,0},
 603    {"innodb_io_pattern_trace", OPT_INNODB_IO_PATTERN_TRACE,
 604     "Create/Drop the internal hash table for IO pattern tracing.",
 605     (gptr*) &srv_io_pattern_trace, (gptr*) &srv_io_pattern_trace,
 606 diff -ruN a/sql/set_var.cc b/sql/set_var.cc
 607 --- a/sql/set_var.cc    2009-08-27 18:42:17.000000000 +0900
 608 +++ b/sql/set_var.cc    2009-08-27 18:42:59.000000000 +0900
 609 @@ -540,6 +540,8 @@
 610  sys_var_enum   sys_innodb_adaptive_checkpoint("innodb_adaptive_checkpoint",
 611                             &srv_adaptive_checkpoint,
 612                             &innodb_adaptive_checkpoint_typelib, fix_innodb_adaptive_checkpoint);
 613 +sys_var_long_ptr       sys_innodb_dict_size_limit("innodb_dict_size_limit",
 614 +                                                   &srv_dict_size_limit);
 615  sys_var_long_ptr  sys_innodb_show_locks_held(
 616                                          "innodb_show_locks_held",
 617                                          &srv_show_locks_held);
 618 @@ -930,6 +932,7 @@
 619    &sys_innodb_read_ahead,
 620    &sys_innodb_enable_unsafe_group_commit,
 621    &sys_innodb_adaptive_checkpoint,
 622 +  &sys_innodb_dict_size_limit,
 623    &sys_innodb_show_locks_held,
 624    &sys_innodb_show_verbose_locks,
 625    &sys_innodb_io_pattern_trace,
 626 @@ -1084,6 +1087,7 @@
 627    {sys_innodb_adaptive_checkpoint.name, (char*) &sys_innodb_adaptive_checkpoint, SHOW_SYS},
 628    {"innodb_read_io_threads", (char*) &innobase_read_io_threads, SHOW_LONG},
 629    {"innodb_write_io_threads", (char*) &innobase_write_io_threads, SHOW_LONG},
 630 +  {sys_innodb_dict_size_limit.name, (char*) &sys_innodb_dict_size_limit, SHOW_SYS},
 631    {sys_innodb_io_pattern_trace.name, (char*) &sys_innodb_io_pattern_trace, SHOW_SYS},
 632    {sys_innodb_io_pattern_trace_running.name, (char*) &sys_innodb_io_pattern_trace_running, SHOW_SYS},
 633    {sys_innodb_io_pattern_size_limit.name, (char*) &sys_innodb_io_pattern_size_limit, SHOW_SYS},