storage/heap/ha_heap.cc

/*
   Copyright (c) 2000, 2011, Oracle and/or its affiliates

   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 */


#ifdef USE_PRAGMA_IMPLEMENTATION
#pragma implementation				// gcc: Class implementation
#endif

#define MYSQL_SERVER 1
#include "heapdef.h"
#include "sql_priv.h"
#include "sql_plugin.h"
#include "ha_heap.h"
#include "sql_base.h"

static handler *heap_create_handler(handlerton *, TABLE_SHARE *, MEM_ROOT *);
static int heap_prepare_hp_create_info(TABLE *, bool, HP_CREATE_INFO *);


static int heap_panic(handlerton *hton, ha_panic_function flag)
{
  return hp_panic(flag);
}


static int heap_drop_table(handlerton *hton, const char *path)
{
  int error= heap_delete_table(path);
  return error == ENOENT ? -1 : error;
}

int heap_init(void *p)
{
  handlerton *heap_hton;

  init_heap_psi_keys();

  heap_hton= (handlerton *)p;
  heap_hton->db_type=    DB_TYPE_HEAP;
  heap_hton->create=     heap_create_handler;
  heap_hton->panic=      heap_panic;
  heap_hton->drop_table= heap_drop_table;
  heap_hton->flags=      HTON_CAN_RECREATE;

  return 0;
}

static handler *heap_create_handler(handlerton *hton,
                                    TABLE_SHARE *table,
                                    MEM_ROOT *mem_root)
{
  return new (mem_root) ha_heap(hton, table);
}


/*****************************************************************************
** HEAP tables
*****************************************************************************/

ha_heap::ha_heap(handlerton *hton, TABLE_SHARE *table_arg)
  :handler(hton, table_arg), file(0), records_changed(0), key_stat_version(0),
  internal_table(0)
{}

/*
  Hash index statistics is updated (copied from HP_KEYDEF::hash_buckets to
  rec_per_key) after 1/HEAP_STATS_UPDATE_THRESHOLD fraction of table records
  have been inserted/updated/deleted. delete_all_rows() and table flush cause
  immediate update.

  NOTE
   hash index statistics must be updated when number of table records changes
   from 0 to non-zero value and vice versa. Otherwise records_in_range may
   erroneously return 0 and 'range' may miss records.
*/
#define HEAP_STATS_UPDATE_THRESHOLD 10

int ha_heap::open(const char *name, int mode, uint test_if_locked)
{
  internal_table= MY_TEST(test_if_locked & HA_OPEN_INTERNAL_TABLE);
  if (internal_table || (!(file= heap_open(name, mode)) && my_errno == ENOENT))
  {
    HP_CREATE_INFO create_info;
    my_bool created_new_share;
    int rc;
    file= 0;
    if (heap_prepare_hp_create_info(table, internal_table, &create_info))
      goto end;
    create_info.pin_share= TRUE;

    rc= heap_create(name, &create_info, &internal_share, &created_new_share);
    my_free(create_info.keydef);
    if (rc)
      goto end;

    implicit_emptied= MY_TEST(created_new_share);
    if (internal_table)
      file= heap_open_from_share(internal_share, mode);
    else
      file= heap_open_from_share_and_register(internal_share, mode);

    if (!file)
    {
      heap_release_share(internal_share, internal_table);
      goto end;
    }
  }

  ref_length= sizeof(HEAP_PTR);
  /* Initialize variables for the opened table */
  set_keys_for_scanning();
  /*
    We cannot run update_key_stats() here because we do not have a
    lock on the table. The 'records' count might just be changed
    temporarily at this moment and we might get wrong statistics (Bug
    #10178). Instead we request for update. This will be done in
    ha_heap::info(), which is always called before key statistics are
    used.
    */
  key_stat_version= file->s->key_stat_version-1;
end:
  return (file ? 0 : 1);
}

int ha_heap::close(void)
{
  return internal_table ? hp_close(file) : heap_close(file);
}


/*
  Create a copy of this table

  DESCRIPTION
    Do same as default implementation but use file->s->name instead of
    table->s->path. This is needed by Windows where the clone() call sees
    '/'-delimited path in table->s->path, while ha_heap::open() was called
    with '\'-delimited path.
*/

handler *ha_heap::clone(const char *name, MEM_ROOT *mem_root)
{
  handler *new_handler= get_new_handler(table->s, mem_root, ht);
  if (new_handler && !new_handler->ha_open(table, file->s->name, table->db_stat,
                                           HA_OPEN_IGNORE_IF_LOCKED))
    return new_handler;
  return NULL;  /* purecov: inspected */
}


/*
  Compute which keys to use for scanning

  SYNOPSIS
    set_keys_for_scanning()
    no parameter

  DESCRIPTION
    Set the bitmap btree_keys, which is used when the upper layers ask
    which keys to use for scanning. For each btree index the
    corresponding bit is set.

  RETURN
    void
*/

void ha_heap::set_keys_for_scanning(void)
{
  btree_keys.clear_all();
  for (uint i= 0 ; i < table->s->keys ; i++)
  {
    if (table->key_info[i].algorithm == HA_KEY_ALG_BTREE)
      btree_keys.set_bit(i);
  }
}


int ha_heap::can_continue_handler_scan()
{
  int error= 0;
  if ((file->key_version != file->s->key_version && inited == INDEX) ||
      (file->file_version != file->s->file_version && inited == RND))
  {
    /* Data changed, not safe to do index or rnd scan */
    error= HA_ERR_RECORD_CHANGED;
  }
  return error;
}


void ha_heap::update_key_stats()
{
  for (uint i= 0; i < table->s->keys; i++)
  {
    KEY *key=table->key_info+i;
    if (!key->rec_per_key)
      continue;
    if (key->algorithm != HA_KEY_ALG_BTREE)
    {
      if (key->flags & HA_NOSAME)
        key->rec_per_key[key->user_defined_key_parts-1]= 1;
      else
      {
        ha_rows hash_buckets= file->s->keydef[i].hash_buckets;
        ulong no_records= hash_buckets ? (ulong)(file->s->records/hash_buckets) : 2;
        if (no_records < 2)
          no_records= 2;
        key->rec_per_key[key->user_defined_key_parts-1]= no_records;
      }
    }
  }
  records_changed= 0;
  /* At the end of update_key_stats() we can proudly claim they are OK. */
  key_stat_version= file->s->key_stat_version;
}


int ha_heap::write_row(const uchar * buf)
{
  int res;
  if (table->next_number_field && buf == table->record[0])
  {
    if ((res= update_auto_increment()))
      return res;
  }
  res= heap_write(file,buf);
  if (!res && (++records_changed*HEAP_STATS_UPDATE_THRESHOLD >
               file->s->records))
  {
    /*
       We can perform this safely since only one writer at the time is
       allowed on the table.
    */
    records_changed= 0;
    file->s->key_stat_version++;
  }
  return res;
}

int ha_heap::update_row(const uchar * old_data, const uchar * new_data)
{
  int res;
  res= heap_update(file,old_data,new_data);
  if (!res && ++records_changed*HEAP_STATS_UPDATE_THRESHOLD >
              file->s->records)
  {
    /*
       We can perform this safely since only one writer at the time is
       allowed on the table.
    */
    records_changed= 0;
    file->s->key_stat_version++;
  }
  return res;
}

int ha_heap::delete_row(const uchar * buf)
{
  int res;
  res= heap_delete(file,buf);
  if (!res && table->s->tmp_table == NO_TMP_TABLE &&
      ++records_changed*HEAP_STATS_UPDATE_THRESHOLD > file->s->records)
  {
    /*
       We can perform this safely since only one writer at the time is
       allowed on the table.
    */
    records_changed= 0;
    file->s->key_stat_version++;
  }
  return res;
}

int ha_heap::index_read_map(uchar *buf, const uchar *key,
                            key_part_map keypart_map,
                            enum ha_rkey_function find_flag)
{
  DBUG_ASSERT(inited==INDEX);
  int error = heap_rkey(file,buf,active_index, key, keypart_map, find_flag);
  return error;
}

int ha_heap::index_read_last_map(uchar *buf, const uchar *key,
                                 key_part_map keypart_map)
{
  DBUG_ASSERT(inited==INDEX);
  int error= heap_rkey(file, buf, active_index, key, keypart_map,
		       HA_READ_PREFIX_LAST);
  return error;
}

int ha_heap::index_read_idx_map(uchar *buf, uint index, const uchar *key,
                                key_part_map keypart_map,
                                enum ha_rkey_function find_flag)
{
  int error = heap_rkey(file, buf, index, key, keypart_map, find_flag);
  return error;
}

int ha_heap::index_next(uchar * buf)
{
  DBUG_ASSERT(inited==INDEX);
  int error=heap_rnext(file,buf);
  return error;
}

int ha_heap::index_prev(uchar * buf)
{
  DBUG_ASSERT(inited==INDEX);
  int error=heap_rprev(file,buf);
  return error;
}

int ha_heap::index_first(uchar * buf)
{
  DBUG_ASSERT(inited==INDEX);
  int error=heap_rfirst(file, buf, active_index);
  return error;
}

int ha_heap::index_last(uchar * buf)
{
  DBUG_ASSERT(inited==INDEX);
  int error=heap_rlast(file, buf, active_index);
  return error;
}

int ha_heap::rnd_init(bool scan)
{
  return scan ? heap_scan_init(file) : 0;
}

int ha_heap::rnd_next(uchar *buf)
{
  int error=heap_scan(file, buf);
  return error;
}

int ha_heap::rnd_pos(uchar * buf, uchar *pos)
{
  int error;
  HEAP_PTR heap_position;
  memcpy(&heap_position, pos, sizeof(HEAP_PTR));
  error=heap_rrnd(file, buf, heap_position);
  return error;
}

void ha_heap::position(const uchar *record)
{
  *(HEAP_PTR*) ref= heap_position(file);	// Ref is aligned
}

int ha_heap::info(uint flag)
{
  HEAPINFO hp_info;

  (void) heap_info(file,&hp_info,flag);

  errkey=                     hp_info.errkey;
  stats.records=              hp_info.records;
  stats.deleted=              hp_info.deleted;
  stats.mean_rec_length=      hp_info.reclength;
  stats.data_file_length=     hp_info.data_length;
  stats.index_file_length=    hp_info.index_length;
  stats.max_data_file_length= hp_info.max_records * hp_info.reclength;
  stats.delete_length=        hp_info.deleted * hp_info.reclength;
  stats.create_time=          (ulong) hp_info.create_time;
  if (flag & HA_STATUS_AUTO)
    stats.auto_increment_value= hp_info.auto_increment;
  /*
    If info() is called for the first time after open(), we will still
    have to update the key statistics. Hoping that a table lock is now
    in place.
  */
  if (key_stat_version != file->s->key_stat_version)
    update_key_stats();
  return 0;
}


int ha_heap::extra(enum ha_extra_function operation)
{
  return heap_extra(file,operation);
}


int ha_heap::reset()
{
  return heap_reset(file);
}


int ha_heap::delete_all_rows()
{
  heap_clear(file);
  if (table->s->tmp_table == NO_TMP_TABLE)
  {
    /*
       We can perform this safely since only one writer at the time is
       allowed on the table.
    */
    file->s->key_stat_version++;
  }
  return 0;
}


int ha_heap::reset_auto_increment(ulonglong value)
{
  file->s->auto_increment= value;
  return 0;
}


int ha_heap::external_lock(THD *thd, int lock_type)
{
#if !defined(DBUG_OFF) && defined(EXTRA_DEBUG)
  if (lock_type == F_UNLCK && file->s->changed && heap_check_heap(file, 0))
    return HA_ERR_CRASHED;
#endif
  return 0;					// No external locking
}


/*
  Disable indexes.

  SYNOPSIS
    disable_indexes()
    mode        mode of operation:
                HA_KEY_SWITCH_NONUNIQ      disable all non-unique keys
                HA_KEY_SWITCH_ALL          disable all keys
                HA_KEY_SWITCH_NONUNIQ_SAVE dis. non-uni. and make persistent
                HA_KEY_SWITCH_ALL_SAVE     dis. all keys and make persistent

  DESCRIPTION
    Disable indexes and clear keys to use for scanning.

  IMPLEMENTATION
    HA_KEY_SWITCH_NONUNIQ       is not implemented.
    HA_KEY_SWITCH_NONUNIQ_SAVE  is not implemented with HEAP.
    HA_KEY_SWITCH_ALL_SAVE      is not implemented with HEAP.

  RETURN
    0  ok
    HA_ERR_WRONG_COMMAND  mode not implemented.
*/

int ha_heap::disable_indexes(uint mode)
{
  int error;

  if (mode == HA_KEY_SWITCH_ALL)
  {
    if (!(error= heap_disable_indexes(file)))
      set_keys_for_scanning();
  }
  else
  {
    /* mode not implemented */
    error= HA_ERR_WRONG_COMMAND;
  }
  return error;
}


/*
  Enable indexes.

  SYNOPSIS
    enable_indexes()
    mode        mode of operation:
                HA_KEY_SWITCH_NONUNIQ      enable all non-unique keys
                HA_KEY_SWITCH_ALL          enable all keys
                HA_KEY_SWITCH_NONUNIQ_SAVE en. non-uni. and make persistent
                HA_KEY_SWITCH_ALL_SAVE     en. all keys and make persistent

  DESCRIPTION
    Enable indexes and set keys to use for scanning.
    The indexes might have been disabled by disable_index() before.
    The function works only if both data and indexes are empty,
    since the heap storage engine cannot repair the indexes.
    To be sure, call handler::delete_all_rows() before.

  IMPLEMENTATION
    HA_KEY_SWITCH_NONUNIQ       is not implemented.
    HA_KEY_SWITCH_NONUNIQ_SAVE  is not implemented with HEAP.
    HA_KEY_SWITCH_ALL_SAVE      is not implemented with HEAP.

  RETURN
    0  ok
    HA_ERR_CRASHED  data or index is non-empty. Delete all rows and retry.
    HA_ERR_WRONG_COMMAND  mode not implemented.
*/

int ha_heap::enable_indexes(uint mode)
{
  int error;

  if (mode == HA_KEY_SWITCH_ALL)
  {
    if (!(error= heap_enable_indexes(file)))
      set_keys_for_scanning();
  }
  else
  {
    /* mode not implemented */
    error= HA_ERR_WRONG_COMMAND;
  }
  return error;
}


/*
  Test if indexes are disabled.

  SYNOPSIS
    indexes_are_disabled()
    no parameters

  RETURN
    0  indexes are not disabled
    1  all indexes are disabled
   [2  non-unique indexes are disabled - NOT YET IMPLEMENTED]
*/

int ha_heap::indexes_are_disabled(void)
{
  return heap_indexes_are_disabled(file);
}

THR_LOCK_DATA **ha_heap::store_lock(THD *thd,
				    THR_LOCK_DATA **to,
				    enum thr_lock_type lock_type)
{
  if (lock_type != TL_IGNORE && file->lock.type == TL_UNLOCK)
    file->lock.type=lock_type;
  *to++= &file->lock;
  return to;
}

/*
  We have to ignore ENOENT entries as the HEAP table is created on open and
  not when doing a CREATE on the table.
*/

int ha_heap::delete_table(const char *name)
{
  return heap_drop_table(0, name);
}


void ha_heap::drop_table(const char *name)
{
  file->s->delete_on_close= 1;
  ha_close();
}


int ha_heap::rename_table(const char * from, const char * to)
{
  return heap_rename(from,to);
}


ha_rows ha_heap::records_in_range(uint inx, const key_range *min_key,
                                  const key_range *max_key, page_range *pages)
{
  KEY *key=table->key_info+inx;
  if (key->algorithm == HA_KEY_ALG_BTREE)
    return hp_rb_records_in_range(file, inx, min_key, max_key);

  if (!min_key || !max_key ||
      min_key->length != max_key->length ||
      min_key->length != key->key_length ||
      min_key->flag != HA_READ_KEY_EXACT ||
      max_key->flag != HA_READ_AFTER_KEY)
    return HA_POS_ERROR;			// Can only use exact keys

  if (stats.records <= 1)
    return stats.records;

  /* Assert that info() did run. We need current statistics here. */
  DBUG_ASSERT(key_stat_version == file->s->key_stat_version);
  return key->rec_per_key[key->user_defined_key_parts-1];
}


static int heap_prepare_hp_create_info(TABLE *table_arg, bool internal_table,
                                       HP_CREATE_INFO *hp_create_info)
{
  TABLE_SHARE *share= table_arg->s;
  uint key, parts, mem_per_row= 0, keys= share->keys;
  uint auto_key= 0, auto_key_type= 0;
  ha_rows max_rows;
  HP_KEYDEF *keydef;
  HA_KEYSEG *seg;
  bool found_real_auto_increment= 0;

  bzero(hp_create_info, sizeof(*hp_create_info));

  for (key= parts= 0; key < keys; key++)
    parts+= table_arg->key_info[key].user_defined_key_parts;

  if (!my_multi_malloc(hp_key_memory_HP_KEYDEF,
                       MYF(MY_WME | MY_THREAD_SPECIFIC),
                       &keydef, keys * sizeof(HP_KEYDEF),
                       &seg, parts * sizeof(HA_KEYSEG),
                       NULL))
    return my_errno;
  for (key= 0; key < keys; key++)
  {
    KEY *pos= table_arg->key_info+key;
    KEY_PART_INFO *key_part=     pos->key_part;
    KEY_PART_INFO *key_part_end= key_part + pos->user_defined_key_parts;

    keydef[key].keysegs=   (uint) pos->user_defined_key_parts;
    keydef[key].flag=      (pos->flags & (HA_NOSAME | HA_NULL_ARE_EQUAL));
    keydef[key].seg=       seg;

    switch (pos->algorithm) {
    case HA_KEY_ALG_UNDEF:
    case HA_KEY_ALG_HASH:
      keydef[key].algorithm= HA_KEY_ALG_HASH;
      mem_per_row+= sizeof(char*) * 2; // = sizeof(HASH_INFO)
      break;
    case HA_KEY_ALG_BTREE:
      keydef[key].algorithm= HA_KEY_ALG_BTREE;
      mem_per_row+=sizeof(TREE_ELEMENT)+pos->key_length+sizeof(char*);
      break;
    default:
      DBUG_ASSERT(0); // cannot happen
    }

    for (; key_part != key_part_end; key_part++, seg++)
    {
      Field *field= key_part->field;

      if (pos->algorithm == HA_KEY_ALG_BTREE)
	seg->type= field->key_type();
      else
      {
        if ((seg->type = field->key_type()) != (int) HA_KEYTYPE_TEXT &&
            seg->type != HA_KEYTYPE_VARTEXT1 &&
            seg->type != HA_KEYTYPE_VARTEXT2 &&
            seg->type != HA_KEYTYPE_VARBINARY1 &&
            seg->type != HA_KEYTYPE_VARBINARY2 &&
            seg->type != HA_KEYTYPE_BIT)
          seg->type= HA_KEYTYPE_BINARY;
      }
      seg->start=   (uint) key_part->offset;
      seg->length=  (uint) key_part->length;
      seg->flag=    key_part->key_part_flag;

      if (field->flags & (ENUM_FLAG | SET_FLAG))
        seg->charset= &my_charset_bin;
      else
        seg->charset= field->charset_for_protocol();
      if (field->null_ptr)
      {
	seg->null_bit= field->null_bit;
	seg->null_pos= (uint) (field->null_ptr - (uchar*) table_arg->record[0]);
      }
      else
      {
	seg->null_bit= 0;
	seg->null_pos= 0;
      }
      if (field->flags & AUTO_INCREMENT_FLAG &&
          table_arg->found_next_number_field &&
          key == share->next_number_index)
      {
        /*
          Store key number and type for found auto_increment key
          We have to store type as seg->type can differ from it
        */
        auto_key= key+ 1;
	auto_key_type= field->key_type();
      }
      if (seg->type == HA_KEYTYPE_BIT)
      {
        seg->bit_length= ((Field_bit *) field)->bit_len;
        seg->bit_start= ((Field_bit *) field)->bit_ofs;
        seg->bit_pos= (uint) (((Field_bit *) field)->bit_ptr -
                                          (uchar*) table_arg->record[0]);
      }
      else
      {
        seg->bit_length= seg->bit_start= 0;
        seg->bit_pos= 0;
      }
    }
  }
  mem_per_row+= MY_ALIGN(MY_MAX(share->reclength, sizeof(char*)) + 1, sizeof(char*));
  if (table_arg->found_next_number_field)
  {
    keydef[share->next_number_index].flag|= HA_AUTO_KEY;
    found_real_auto_increment= share->next_number_key_offset == 0;
  }
  hp_create_info->auto_key= auto_key;
  hp_create_info->auto_key_type= auto_key_type;
  hp_create_info->max_table_size=current_thd->variables.max_heap_table_size;
  hp_create_info->with_auto_increment= found_real_auto_increment;
  hp_create_info->internal_table= internal_table;

  max_rows= (ha_rows) (hp_create_info->max_table_size / mem_per_row);
  if (share->max_rows && share->max_rows < max_rows)
    max_rows= share->max_rows;

  hp_create_info->max_records= (ulong) MY_MIN(max_rows, ULONG_MAX);
  hp_create_info->min_records= (ulong) MY_MIN(share->min_rows, ULONG_MAX);
  hp_create_info->keys= share->keys;
  hp_create_info->reclength= share->reclength;
  hp_create_info->keydef= keydef;
  return 0;
}


int ha_heap::create(const char *name, TABLE *table_arg,
		    HA_CREATE_INFO *create_info)
{
  int error;
  my_bool created;
  HP_CREATE_INFO hp_create_info;

  error= heap_prepare_hp_create_info(table_arg, internal_table,
                                     &hp_create_info);
  if (error)
    return error;
  hp_create_info.auto_increment= (create_info->auto_increment_value ?
				  create_info->auto_increment_value - 1 : 0);
  error= heap_create(name, &hp_create_info, &internal_share, &created);
  my_free(hp_create_info.keydef);
  DBUG_ASSERT(file == 0);
  return (error);
}


void ha_heap::update_create_info(HA_CREATE_INFO *create_info)
{
  table->file->info(HA_STATUS_AUTO);
  if (!(create_info->used_fields & HA_CREATE_USED_AUTO))
    create_info->auto_increment_value= stats.auto_increment_value;
}

void ha_heap::get_auto_increment(ulonglong offset, ulonglong increment,
                                 ulonglong nb_desired_values,
                                 ulonglong *first_value,
                                 ulonglong *nb_reserved_values)
{
  ha_heap::info(HA_STATUS_AUTO);
  *first_value= stats.auto_increment_value;
  /* such table has only table-level locking so reserves up to +inf */
  *nb_reserved_values= ULONGLONG_MAX;
}


bool ha_heap::check_if_incompatible_data(HA_CREATE_INFO *info,
					 uint table_changes)
{
  /* Check that auto_increment value was not changed */
  if ((info->used_fields & HA_CREATE_USED_AUTO &&
       info->auto_increment_value != 0) ||
      table_changes == IS_EQUAL_NO ||
      table_changes & IS_EQUAL_PACK_LENGTH) // Not implemented yet
    return COMPATIBLE_DATA_NO;
  return COMPATIBLE_DATA_YES;
}


/**
  Find record by unique index (used in temporary tables with the index)

  @param record          (IN|OUT) the record to find
  @param unique_idx      (IN) number of index (for this engine)

  @note It is like hp_search but uses function for raw where hp_search
        uses functions for index.

  @retval  0 OK
  @retval  1 Not found
  @retval -1 Error
*/

int ha_heap::find_unique_row(uchar *record, uint unique_idx)
{
  DBUG_ENTER("ha_heap::find_unique_row");
  HP_SHARE *share= file->s;
  DBUG_ASSERT(inited==NONE);
  HP_KEYDEF *keyinfo= share->keydef + unique_idx;
  DBUG_ASSERT(keyinfo->algorithm == HA_KEY_ALG_HASH);
  DBUG_ASSERT(keyinfo->flag & HA_NOSAME);
  if (!share->records)
    DBUG_RETURN(1); // not found
  HASH_INFO *pos= hp_find_hash(&keyinfo->block,
                               hp_mask(hp_rec_hashnr(keyinfo, record),
                                       share->blength, share->records));
  do
  {
    if (!hp_rec_key_cmp(keyinfo, pos->ptr_to_rec, record))
    {
      file->current_hash_ptr= pos;
      file->current_ptr= pos->ptr_to_rec;
      file->update = HA_STATE_AKTIV;
      /*
        We compare it only by record in the index, so better to read all
        records.
      */
      memcpy(record, file->current_ptr, (size_t) share->reclength);

      DBUG_RETURN(0); // found and position set
    }
  }
  while ((pos= pos->next_key));
  DBUG_RETURN(1); // not found
}

struct st_mysql_storage_engine heap_storage_engine=
{ MYSQL_HANDLERTON_INTERFACE_VERSION };

maria_declare_plugin(heap)
{
  MYSQL_STORAGE_ENGINE_PLUGIN,
  &heap_storage_engine,
  "MEMORY",
  "MySQL AB",
  "Hash based, stored in memory, useful for temporary tables",
  PLUGIN_LICENSE_GPL,
  heap_init,
  NULL,
  0x0100, /* 1.0 */
  NULL,                       /* status variables                */
  NULL,                       /* system variables                */
  "1.0",                      /* string version */
  MariaDB_PLUGIN_MATURITY_STABLE /* maturity */
}
maria_declare_plugin_end;