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mysql/src/5.1-dbg/sql/ha_heap.cc

Go to the documentation of this file.

/* Copyright (C) 2000,2004 MySQL AB & MySQL Finland AB & TCX DataKonsult AB

   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 */


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

#include "mysql_priv.h"
#include <myisampack.h>
#include "ha_heap.h"


static handler *heap_create_handler(TABLE_SHARE *table, MEM_ROOT *mem_root);

handlerton heap_hton;

int heap_init()
{
  heap_hton.state=      SHOW_OPTION_YES;
  heap_hton.db_type=    DB_TYPE_HEAP;
  heap_hton.create=     heap_create_handler;
  heap_hton.panic=      heap_panic;
  heap_hton.flags=      HTON_CAN_RECREATE;
  return 0;
}

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


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

ha_heap::ha_heap(TABLE_SHARE *table_arg)
  :handler(&heap_hton, table_arg), file(0), records_changed(0),
  key_stat_version(0)
{}


static const char *ha_heap_exts[] = {
  NullS
};

const char **ha_heap::bas_ext() const
{
  return ha_heap_exts;
}

/*
  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)
{
  if (!(file= heap_open(name, mode)) && my_errno == ENOENT)
  {
    HA_CREATE_INFO create_info;
    bzero(&create_info, sizeof(create_info));
    if (!create(name, table, &create_info))
    {
      file= heap_open(name, mode);
      implicit_emptied= 1;
    }
  }
  ref_length= sizeof(HEAP_PTR);
  if (file)
  {
    /* 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;
  }
  return (file ? 0 : 1);
}

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


/*
  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);
  }
}


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->key_parts-1]= 1;
      else
      {
        ha_rows hash_buckets= file->s->keydef[i].hash_buckets;
        uint no_records= hash_buckets ? file->s->records/hash_buckets : 2;
        if (no_records < 2)
          no_records= 2;
        key->rec_per_key[key->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(byte * buf)
{
  int res;
  statistic_increment(table->in_use->status_var.ha_write_count,&LOCK_status);
  if (table->timestamp_field_type & TIMESTAMP_AUTO_SET_ON_INSERT)
    table->timestamp_field->set_time();
  if (table->next_number_field && buf == table->record[0])
    update_auto_increment();
  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.
    */
    file->s->key_stat_version++;
  }
  return res;
}

int ha_heap::update_row(const byte * old_data, byte * new_data)
{
  int res;
  statistic_increment(table->in_use->status_var.ha_update_count,&LOCK_status);
  if (table->timestamp_field_type & TIMESTAMP_AUTO_SET_ON_UPDATE)
    table->timestamp_field->set_time();
  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.
    */
    file->s->key_stat_version++;
  }
  return res;
}

int ha_heap::delete_row(const byte * buf)
{
  int res;
  statistic_increment(table->in_use->status_var.ha_delete_count,&LOCK_status);
  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.
    */
    file->s->key_stat_version++;
  }
  return res;
}

int ha_heap::index_read(byte * buf, const byte * key, uint key_len,
                        enum ha_rkey_function find_flag)
{
  DBUG_ASSERT(inited==INDEX);
  statistic_increment(table->in_use->status_var.ha_read_key_count,
                      &LOCK_status);
  int error = heap_rkey(file,buf,active_index, key, key_len, find_flag);
  table->status = error ? STATUS_NOT_FOUND : 0;
  return error;
}

int ha_heap::index_read_last(byte *buf, const byte *key, uint key_len)
{
  DBUG_ASSERT(inited==INDEX);
  statistic_increment(table->in_use->status_var.ha_read_key_count,
                      &LOCK_status);
  int error= heap_rkey(file, buf, active_index, key, key_len,
                       HA_READ_PREFIX_LAST);
  table->status= error ? STATUS_NOT_FOUND : 0;
  return error;
}

int ha_heap::index_read_idx(byte * buf, uint index, const byte * key,
                            uint key_len, enum ha_rkey_function find_flag)
{
  statistic_increment(table->in_use->status_var.ha_read_key_count,
                      &LOCK_status);
  int error = heap_rkey(file, buf, index, key, key_len, find_flag);
  table->status = error ? STATUS_NOT_FOUND : 0;
  return error;
}

int ha_heap::index_next(byte * buf)
{
  DBUG_ASSERT(inited==INDEX);
  statistic_increment(table->in_use->status_var.ha_read_next_count,
                      &LOCK_status);
  int error=heap_rnext(file,buf);
  table->status=error ? STATUS_NOT_FOUND: 0;
  return error;
}

int ha_heap::index_prev(byte * buf)
{
  DBUG_ASSERT(inited==INDEX);
  statistic_increment(table->in_use->status_var.ha_read_prev_count,
                      &LOCK_status);
  int error=heap_rprev(file,buf);
  table->status=error ? STATUS_NOT_FOUND: 0;
  return error;
}

int ha_heap::index_first(byte * buf)
{
  DBUG_ASSERT(inited==INDEX);
  statistic_increment(table->in_use->status_var.ha_read_first_count,
                      &LOCK_status);
  int error=heap_rfirst(file, buf, active_index);
  table->status=error ? STATUS_NOT_FOUND: 0;
  return error;
}

int ha_heap::index_last(byte * buf)
{
  DBUG_ASSERT(inited==INDEX);
  statistic_increment(table->in_use->status_var.ha_read_last_count,
                      &LOCK_status);
  int error=heap_rlast(file, buf, active_index);
  table->status=error ? STATUS_NOT_FOUND: 0;
  return error;
}

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

int ha_heap::rnd_next(byte *buf)
{
  statistic_increment(table->in_use->status_var.ha_read_rnd_next_count,
                      &LOCK_status);
  int error=heap_scan(file, buf);
  table->status=error ? STATUS_NOT_FOUND: 0;
  return error;
}

int ha_heap::rnd_pos(byte * buf, byte *pos)
{
  int error;
  HEAP_PTR position;
  statistic_increment(table->in_use->status_var.ha_read_rnd_count,
                      &LOCK_status);
  memcpy_fixed((char*) &position,pos,sizeof(HEAP_PTR));
  error=heap_rrnd(file, buf, position);
  table->status=error ? STATUS_NOT_FOUND: 0;
  return error;
}

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

void ha_heap::info(uint flag)
{
  HEAPINFO info;
  (void) heap_info(file,&info,flag);

  errkey= info.errkey;
  stats.records = info.records;
  stats.deleted = info.deleted;
  stats.mean_rec_length=info.reclength;
  stats.data_file_length=info.data_length;
  stats.index_file_length=info.index_length;
  stats.max_data_file_length= info.max_records* info.reclength;
  stats.delete_length= info.deleted * info.reclength;
  if (flag & HA_STATUS_AUTO)
    stats.auto_increment_value= 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();
}


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::external_lock(THD *thd, int lock_type)
{
  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)
{
  int error= heap_delete_table(name);
  return error == ENOENT ? 0 : error;
}


void ha_heap::drop_table(const char *name)
{
  heap_drop_table(file);
  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, key_range *min_key,
                                  key_range *max_key)
{
  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->key_parts-1];
}


int ha_heap::create(const char *name, TABLE *table_arg,
                    HA_CREATE_INFO *create_info)
{
  uint key, parts, mem_per_row= 0, keys= table_arg->s->keys;
  uint auto_key= 0, auto_key_type= 0;
  ha_rows max_rows;
  HP_KEYDEF *keydef;
  HA_KEYSEG *seg;
  int error;
  TABLE_SHARE *share= table_arg->s;
  bool found_real_auto_increment= 0;

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

  if (!(keydef= (HP_KEYDEF*) my_malloc(keys * sizeof(HP_KEYDEF) +
                                       parts * sizeof(HA_KEYSEG),
                                       MYF(MY_WME))))
    return my_errno;
  seg= my_reinterpret_cast(HA_KEYSEG*) (keydef + keys);
  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->key_parts;

    keydef[key].keysegs=   (uint) pos->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_BINARY;
      }
      seg->start=   (uint) key_part->offset;
      seg->length=  (uint) key_part->length;
      seg->flag=    key_part->key_part_flag;

      seg->charset= field->charset();
      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();
      }
    }
  }
  mem_per_row+= MY_ALIGN(share->reclength + 1, sizeof(char*));
  max_rows = (ha_rows) (table_arg->in_use->variables.max_heap_table_size /
                        mem_per_row);
  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 hp_create_info;
  hp_create_info.auto_key= auto_key;
  hp_create_info.auto_key_type= auto_key_type;
  hp_create_info.auto_increment= (create_info->auto_increment_value ?
                                  create_info->auto_increment_value - 1 : 0);
  hp_create_info.max_table_size=current_thd->variables.max_heap_table_size;
  hp_create_info.with_auto_increment= found_real_auto_increment;
  max_rows = (ha_rows) (hp_create_info.max_table_size / mem_per_row);
  error= heap_create(name,
                     keys, keydef, share->reclength,
                     (ulong) ((share->max_rows < max_rows &&
                               share->max_rows) ? 
                              share->max_rows : max_rows),
                     (ulong) share->min_rows, &hp_create_info);
  my_free((gptr) keydef, MYF(0));
  if (file)
    info(HA_STATUS_NO_LOCK | HA_STATUS_CONST | HA_STATUS_VARIABLE);
  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 ((table_changes != IS_EQUAL_YES &&
       info->used_fields & HA_CREATE_USED_AUTO) &&
      info->auto_increment_value != 0)
    return COMPATIBLE_DATA_NO;
  return COMPATIBLE_DATA_YES;
}

struct st_mysql_storage_engine heap_storage_engine=
{ MYSQL_HANDLERTON_INTERFACE_VERSION, &heap_hton};

mysql_declare_plugin(heap)
{
  MYSQL_STORAGE_ENGINE_PLUGIN,
  &heap_storage_engine,
  "MEMORY",
  "MySQL AB",
  "Hash based, stored in memory, useful for temporary tables",
  heap_init,
  NULL,
  0x0100, /* 1.0 */
  0
}
mysql_declare_plugin_end;

---

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