Function create_internal_tmp_table

sql/sql_select.cc:23431–23612

bool create_internal_tmp_table(TABLE *table, KEY *org_keyinfo,
                               TMP_ENGINE_COLUMNDEF *start_recinfo,
                               TMP_ENGINE_COLUMNDEF **recinfo, 
                               ulonglong options)
{
  int error;
  MARIA_KEYDEF *keydefs= 0, *keydef;
  MARIA_UNIQUEDEF uniquedef;
  TABLE_SHARE *share= table->s;
  MARIA_CREATE_INFO create_info;
  bool use_unique= false;
  DBUG_ENTER("create_internal_tmp_table");

  if (share->keys)
  {						// Get keys for ni_create
    HA_KEYSEG *seg;
    DBUG_ASSERT(share->key_parts);

    if (!(multi_alloc_root(&table->mem_root,
                           &seg, sizeof(*seg) * share->key_parts,
                           &keydefs, sizeof(*keydefs) * share->keys,
                           NullS)))
      goto err;
    keydef= keydefs;

    bzero(seg, sizeof(*seg) * share->key_parts);

    /* Note that share->keys may change in the loop ! */
    for (KEY *keyinfo= org_keyinfo, *end_keyinfo= keyinfo + share->keys;
         keyinfo < end_keyinfo ;
         keyinfo++)
    {
      /*
        Note that a similar check is performed during
        subquery_types_allow_materialization. See MDEV-7122 for more details as
        to why. Whenever this changes, it must be updated there as well, for
        all tmp_table engines.
      */
      if (keyinfo->key_length > table->file->max_key_length() ||
          keyinfo->user_defined_key_parts > table->file->max_key_parts() ||
          (keyinfo->flags & HA_UNIQUE_HASH))
      {
        if (!(keyinfo->flags & (HA_NOSAME | HA_UNIQUE_HASH)))
        {
          my_error(ER_INTERNAL_ERROR, MYF(0),
                   "Using too big key for internal temp tables");
          DBUG_RETURN(1);
        }
        /* Can't create a key; Make a unique constraint instead of a key */
        share->total_keys= --share->keys;
        share->key_parts-=     keyinfo->user_defined_key_parts;
        share->ext_key_parts-= keyinfo->ext_key_parts;
        use_unique= true;
        bzero((char*) &uniquedef,sizeof(uniquedef));
        uniquedef.keysegs= keyinfo->user_defined_key_parts;
        uniquedef.seg=seg;
        uniquedef.null_are_equal=1;
        keyinfo->flags|= HA_UNIQUE_HASH;