sql_analyse.cc

/* Copyright (C) 2000 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 */


/* Analyse database */

/* TODO: - Check if any character fields can be of any date type
**	   (date, datetime, year, time, timestamp, newdate)
**	 - Check if any number field should be a timestamp
**	 - type set is out of optimization yet
*/

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

#include "mysql_priv.h"
#include "procedure.h"
#include "sql_analyse.h"
#include <m_ctype.h>

#define MAX_TREEMEM	  8192
#define MAX_TREE_ELEMENTS 256

int sortcmp2(void* cmp_arg __attribute__((unused)),
	     const String *a,const String *b)
{
  return sortcmp(a,b);
}

int stringcmp2(void* cmp_arg __attribute__((unused)),
	     const String *a,const String *b)
{
  return stringcmp(a,b);
}

int compare_double2(void* cmp_arg __attribute__((unused)),
		    const double *s, const double *t)
{
  return compare_double(s,t);
}

int compare_longlong2(void* cmp_arg __attribute__((unused)),
		      const longlong *s, const longlong *t)
{
  return compare_longlong(s,t);
}

int compare_ulonglong2(void* cmp_arg __attribute__((unused)),
		       const ulonglong *s, const ulonglong *t)
{
  return compare_ulonglong(s,t);
}


Procedure *
proc_analyse_init(THD *thd, ORDER *param, select_result *result,
		  List<Item> &field_list)
{
  char *proc_name = (*param->item)->name;
  analyse *pc = new analyse(result);
  field_info **f_info;
  DBUG_ENTER("proc_analyse_init");

  if (!(param = param->next))
  {
    pc->max_tree_elements = MAX_TREE_ELEMENTS;
    pc->max_treemem = MAX_TREEMEM;
  }
  else if (param->next)
  {
    // first parameter
    if ((*param->item)->type() != Item::INT_ITEM ||
	(*param->item)->val() < 0)
    {
      delete pc;
      net_printf(&thd->net, ER_WRONG_PARAMETERS_TO_PROCEDURE, proc_name);
      DBUG_RETURN(0);
    }
    pc->max_tree_elements = (uint) (*param->item)->val_int();
    param = param->next;
    if (param->next)  // no third parameter possible
    {
      delete pc;
      net_printf(&thd->net, ER_WRONG_PARAMCOUNT_TO_PROCEDURE, proc_name);
      DBUG_RETURN(0);
    }
    // second parameter
    if ((*param->item)->type() != Item::INT_ITEM ||
	(*param->item)->val() < 0)
    {
      delete pc;
      net_printf(&thd->net, ER_WRONG_PARAMETERS_TO_PROCEDURE, proc_name);
      DBUG_RETURN(0);
    }
    pc->max_treemem = (uint) (*param->item)->val_int();
  }
  else if ((*param->item)->type() != Item::INT_ITEM ||
	   (*param->item)->val() < 0)
  {
    delete pc;
    net_printf(&thd->net, ER_WRONG_PARAMETERS_TO_PROCEDURE, proc_name);
    DBUG_RETURN(0);
  }
  // if only one parameter was given, it will be the value of max_tree_elements
  else
  {
    pc->max_tree_elements = (uint) (*param->item)->val_int();
    pc->max_treemem = MAX_TREEMEM;
  }

  if (!pc || !(pc->f_info = (field_info**)
	       sql_alloc(sizeof(field_info*)*field_list.elements)))
    DBUG_RETURN(0);
  pc->f_end = pc->f_info + field_list.elements;
  pc->fields = field_list;

  List_iterator_fast<Item> it(pc->fields);
  f_info = pc->f_info;

  Item *item;
  while ((item = it++))
  {
    if (item->result_type() == INT_RESULT)
    {
      // Check if fieldtype is ulonglong
      if (item->type() == Item::FIELD_ITEM &&
	  ((Item_field*) item)->field->type() == FIELD_TYPE_LONGLONG &&
	  ((Field_longlong*) ((Item_field*) item)->field)->unsigned_flag)
	*f_info++ = new field_ulonglong(item, pc);
      else
	*f_info++ = new field_longlong(item, pc);
    }
    if (item->result_type() == REAL_RESULT)
      *f_info++ = new field_real(item, pc);
    if (item->result_type() == STRING_RESULT)
      *f_info++ = new field_str(item, pc);
  }
  DBUG_RETURN(pc);
}


/*
  Return 1 if number, else return 0
  store info about found number in info
  NOTE:It is expected, that elements of 'info' are all zero!
*/

bool test_if_number(NUM_INFO *info, const char *str, uint str_len)
{
  const char *begin, *end = str + str_len;

  DBUG_ENTER("test_if_number");

  /*
    MySQL removes any endspaces of a string, so we must take care only of
    spaces in front of a string
  */
  for (; str != end && isspace(*str); str++) ;
  if (str == end)
    return 0;

  if (*str == '-')
  {
    info->negative = 1;
    if (++str == end || *str == '0') // converting -0 to a number
      return 0;			     // might lose information
  }
  else
    info->negative = 0;
  begin = str;
  for (; str != end && isdigit(*str); str++)
  {
    if (!info->integers && *str == '0' && (str + 1) != end &&
	isdigit(*(str + 1)))
      info->zerofill = 1;	     // could be a postnumber for example
    info->integers++;
  }
  if (str == end && info->integers)
  {
    info->ullval = (ulonglong) strtoull(begin ,NULL, 10);
    if (info->integers == 1)
      return 0;			     // a single number can't be zerofill
    info->maybe_zerofill = 1;
    return 1;			     // a zerofill number, or an integer
  }
  if (*str == '.' || *str == 'e' || *str == 'E')
  {
    if (info->zerofill)		     // can't be zerofill anymore
      return 0;
    if ((str + 1) == end)	     // number was something like '123[.eE]'
    {
      info->ullval = (ulonglong) strtoull(begin, NULL, 10);
      return 1;
    }
    if (*str == 'e' || *str == 'E')  // number may be something like '1e+50'
    {
      str++;
      if (*str != '-' && *str != '+')
	return	0;
      for (str++; str != end && isdigit(*str); str++) ;
      if (str == end)
      {
	info->is_float = 1;	     // we can't use variable decimals here
	return 1;
      }
      return 0;
    }
    for (str++; *(end - 1) == '0'; end--);  // jump over zeros at the end
    if (str == end)		     // number was something like '123.000'
    {
      info->ullval = (ulonglong) strtoull(begin, NULL, 10);
      return 1;
    }
    for (; str != end && isdigit(*str); str++)
      info->decimals++;
    if (str == end)
    {
      info->dval = atod(begin);
      return 1;
    }
  }
  return 0;
}


/*
  Stores the biggest and the smallest value from current 'info'
  to ev_num_info
  If info contains an ulonglong number, which is bigger than
  biggest positive number able to be stored in a longlong variable
  and is marked as negative, function will return 0, else 1.
*/

bool get_ev_num_info(EV_NUM_INFO *ev_info, NUM_INFO *info, const char *num)
{
  if (info->negative)
  {
    if (((longlong) info->ullval) < 0)
      return 0; // Impossible to store as a negative number
    ev_info->llval =  -(longlong) max((ulonglong) -ev_info->llval, 
				      info->ullval);
    ev_info->min_dval = (double) -max(-ev_info->min_dval, info->dval);
  }
  else		// ulonglong is as big as bigint in MySQL
  {
    if ((check_ulonglong(num, info->integers) == REAL_NUM))
      return 0;
    ev_info->ullval = (ulonglong) max(ev_info->ullval, info->ullval);
    ev_info->max_dval =  (double) max(ev_info->max_dval, info->dval);
  }
  return 1;
} // get_ev_num_info


void free_string(String *s)
{
  s->free();
}


void field_str::add()
{
  char buff[MAX_FIELD_WIDTH], *ptr;
  String s(buff, sizeof(buff)), *res;
  ulong length;

  if (!(res = item->val_str(&s)))
  {
    nulls++;
    return;
  }

  if (!(length = res->length()))
    empty++;
  else
  {
    ptr = (char*) res->ptr();
    if (*(ptr + (length - 1)) == ' ')
      must_be_blob = 1;
  }

  if (can_be_still_num)
  {
    bzero((char*) &num_info, sizeof(num_info));
    if (!test_if_number(&num_info, res->ptr(), (uint) length))
      can_be_still_num = 0;
    if (!found)
    {
      bzero((char*) &ev_num_info, sizeof(ev_num_info));
      was_zero_fill = num_info.zerofill;
    }
    else if (num_info.zerofill != was_zero_fill && !was_maybe_zerofill)
      can_be_still_num = 0;  // one more check needed, when length is counted
    if (can_be_still_num)
      can_be_still_num = get_ev_num_info(&ev_num_info, &num_info, res->ptr());
    was_maybe_zerofill = num_info.maybe_zerofill;
  }

  if (!found)
  {
    found = 1;
    min_arg.copy(*res);
    max_arg.copy(*res);
    min_length = max_length = length; sum=length;
  }
  else if (length)
  {
    sum += length;
    if (length < min_length)
      min_length = length;
    if (length > max_length)
      max_length = length;

    if (item->binary)
    {
      if (stringcmp(res, &min_arg) < 0)
	min_arg.copy(*res);
      if (stringcmp(res, &max_arg) > 0)
	max_arg.copy(*res);
    }
    else
    {
      if (sortcmp(res, &min_arg) < 0)
	min_arg.copy(*res);
      if (sortcmp(res, &max_arg) > 0)
	max_arg.copy(*res);
    }
  }

  if (room_in_tree)
  {
    if (res != &s)
      s.copy(*res);
    if (!tree_search(&tree, (void*) &s)) // If not in tree
    {
      s.copy();        // slow, when SAFE_MALLOC is in use
      if (!tree_insert(&tree, (void*) &s, 0))
      {
	room_in_tree = 0;      // Remove tree, out of RAM ?
	delete_tree(&tree);
      }
      else
      {
	bzero((char*) &s, sizeof(s));  // Let tree handle free of this
	if ((treemem += length) > pc->max_treemem)
	{
	  room_in_tree = 0;	 // Remove tree, too big tree
	  delete_tree(&tree);
	}
      }
    }
  }

  if ((num_info.zerofill && (max_length != min_length)) ||
      (was_zero_fill && (max_length != min_length)))
    can_be_still_num = 0; // zerofilled numbers must be of same length
} // field_str::add


void field_real::add()
{
  char buff[MAX_FIELD_WIDTH], *ptr, *end;
  double num = item->val();
  uint length, zero_count, decs;
  TREE_ELEMENT *element;

  if (item->null_value)
  {
    nulls++;
    return;
  }
  if (num == 0.0)
    empty++;

  if ((decs = decimals()) == NOT_FIXED_DEC)
  {
    sprintf(buff, "%g", num);
    length = (uint) strlen(buff);
    if (rint(num) != num)
      max_notzero_dec_len = 1;
  }
  else
  {
#ifdef HAVE_SNPRINTF
    buff[sizeof(buff)-1]=0;			// Safety
    snprintf(buff, sizeof(buff)-1, "%-.*f", (int) decs, num);
#else
    sprintf(buff, "%-.*f", (int) decs, num);
#endif

    length = (uint) strlen(buff);

    // We never need to check further than this
    end = buff + length - 1 - decs + max_notzero_dec_len;

    zero_count = 0;
    for (ptr = buff + length - 1; ptr > end && *ptr == '0'; ptr--)
      zero_count++;

    if ((decs - zero_count > max_notzero_dec_len))
      max_notzero_dec_len = decs - zero_count;
  }

  if (room_in_tree)
  {
    if (!(element = tree_insert(&tree, (void*) &num, 0)))
    {
      room_in_tree = 0;    // Remove tree, out of RAM ?
      delete_tree(&tree);
    }
    /*
      if element->count == 1, this element can be found only once from tree
      if element->count == 2, or more, this element is already in tree
    */
    else if (element->count == 1 && (tree_elements++) >= pc->max_tree_elements)
    {
      room_in_tree = 0;  // Remove tree, too many elements
      delete_tree(&tree);
    }
  }

  if (!found)
  {
    found = 1;
    min_arg = max_arg = sum = num;
    sum_sqr = num * num;
    min_length = max_length = length;
  }
  else if (num != 0.0)
  {
    sum += num;
    sum_sqr += num * num;
    if (length < min_length)
      min_length = length;
    if (length > max_length)
      max_length = length;
    if (compare_double(&num, &min_arg) < 0)
      min_arg = num;
    if (compare_double(&num, &max_arg) > 0)
      max_arg = num;
  }
} // field_real::add


void field_longlong::add()
{
  char buff[MAX_FIELD_WIDTH];
  longlong num = item->val_int();
  uint length = (uint) (longlong10_to_str(num, buff, -10) - buff);
  TREE_ELEMENT *element;

  if (item->null_value)
  {
    nulls++;
    return;
  }
  if (num == 0)
    empty++;

  if (room_in_tree)
  {
    if (!(element = tree_insert(&tree, (void*) &num, 0)))
    {
      room_in_tree = 0;    // Remove tree, out of RAM ?
      delete_tree(&tree);
    }
    /*
      if element->count == 1, this element can be found only once from tree
      if element->count == 2, or more, this element is already in tree
    */
    else if (element->count == 1 && (tree_elements++) >= pc->max_tree_elements)
    {
      room_in_tree = 0;  // Remove tree, too many elements
      delete_tree(&tree);
    }
  }

  if (!found)
  {
    found = 1;
    min_arg = max_arg = sum = num;
    sum_sqr = num * num;
    min_length = max_length = length;
  }
  else if (num != 0)
  {
    sum += num;
    sum_sqr += num * num;
    if (length < min_length)
      min_length = length;
    if (length > max_length)
      max_length = length;
    if (compare_longlong(&num, &min_arg) < 0)
      min_arg = num;
    if (compare_longlong(&num, &max_arg) > 0)
      max_arg = num;
  }
} // field_longlong::add


void field_ulonglong::add()
{
  char buff[MAX_FIELD_WIDTH];
  longlong num = item->val_int();
  uint length = (uint) (longlong10_to_str(num, buff, 10) - buff);
  TREE_ELEMENT *element;

  if (item->null_value)
  {
    nulls++;
    return;
  }
  if (num == 0)
    empty++;

  if (room_in_tree)
  {
    if (!(element = tree_insert(&tree, (void*) &num, 0)))
    {
      room_in_tree = 0;    // Remove tree, out of RAM ?
      delete_tree(&tree);
    }
    /*
      if element->count == 1, this element can be found only once from tree
      if element->count == 2, or more, this element is already in tree
    */
    else if (element->count == 1 && (tree_elements++) >= pc->max_tree_elements)
    {
      room_in_tree = 0;  // Remove tree, too many elements
      delete_tree(&tree);
    }
  }

  if (!found)
  {
    found = 1;
    min_arg = max_arg = sum = num;
    sum_sqr = num * num;
    min_length = max_length = length;
  }
  else if (num != 0)
  {
    sum += num;
    sum_sqr += num * num;
    if (length < min_length)
      min_length = length;
    if (length > max_length)
      max_length = length;
    if (compare_ulonglong((ulonglong*) &num, &min_arg) < 0)
      min_arg = num;
    if (compare_ulonglong((ulonglong*) &num, &max_arg) > 0)
      max_arg = num;
  }
} // field_ulonglong::add


int analyse::send_row(List<Item> &field_list __attribute__((unused)))
{
  field_info **f = f_info;

  rows++;

  for (;f != f_end; f++)
  {
    (*f)->add();
  }
  return 0;
} // analyse::send_row


bool analyse::end_of_records()
{
  field_info **f = f_info;
  char buff[MAX_FIELD_WIDTH];
  String *res, s_min(buff, sizeof(buff)), s_max(buff, sizeof(buff)),
	 ans(buff, sizeof(buff));

  for (; f != f_end; f++)
  {
    func_items[0]->set((*f)->item->full_name());
    if (!(*f)->found)
    {
      func_items[1]->null_value = 1;
      func_items[2]->null_value = 1;
    }
    else
    {
      func_items[1]->null_value = 0;
      res = (*f)->get_min_arg(&s_min);
      func_items[1]->set(res->ptr(), res->length());
      func_items[2]->null_value = 0;
      res = (*f)->get_max_arg(&s_max);
      func_items[2]->set(res->ptr(), res->length());
    }
    func_items[3]->set((longlong) (*f)->min_length);
    func_items[4]->set((longlong) (*f)->max_length);
    func_items[5]->set((longlong) (*f)->empty);
    func_items[6]->set((longlong) (*f)->nulls);
    res = (*f)->avg(&s_max, rows);
    func_items[7]->set(res->ptr(), res->length());
    func_items[8]->null_value = 0;
    res = (*f)->std(&s_max, rows);
    if (!res)
      func_items[8]->null_value = 1;
    else
      func_items[8]->set(res->ptr(), res->length());
    /*
      count the dots, quotas, etc. in (ENUM("a","b","c"...))
      If tree has been removed, don't suggest ENUM.
      treemem is used to measure the size of tree for strings,
      tree_elements is used to count the elements
      max_treemem tells how long the string starting from ENUM("... and
      ending to ..") shall at maximum be. If case is about numbers,
      max_tree_elements will tell the length of the above, now
      every number is considered as length 1
    */
    if (((*f)->treemem || (*f)->tree_elements) &&
	(*f)->tree.elements_in_tree &&
	(((*f)->treemem ? max_treemem : max_tree_elements) >
	 (((*f)->treemem ? (*f)->treemem : (*f)->tree_elements) +
	   ((*f)->tree.elements_in_tree * 3 - 1 + 6))))
    {
      char tmp[331]; //331, because one double prec. num. can be this long
      String tmp_str(tmp, sizeof(tmp));
      TREE_INFO tree_info;

      tree_info.str = &tmp_str;
      tree_info.found = 0;
      tree_info.item = (*f)->item;

      tmp_str.set("ENUM(", 5);
      tree_walk(&(*f)->tree, (*f)->collect_enum(), (char*) &tree_info,
		left_root_right);
      tmp_str.append(')');

      if (!(*f)->nulls)
	tmp_str.append(" NOT NULL");
      output_str_length = tmp_str.length();
      func_items[9]->set(tmp_str.ptr(), tmp_str.length());
      if (result->send_data(result_fields))
	return -1;
      continue;
    }

    ans.length(0);
    if (!(*f)->treemem && !(*f)->tree_elements)
      ans.append("CHAR(0)", 7);
    else if ((*f)->item->type() == Item::FIELD_ITEM)
    {
      switch (((Item_field*) (*f)->item)->field->real_type())
      {
      case FIELD_TYPE_TIMESTAMP:
	ans.append("TIMESTAMP", 9);
	break;
      case FIELD_TYPE_DATETIME:
	ans.append("DATETIME", 8);
	break;
      case FIELD_TYPE_DATE:
      case FIELD_TYPE_NEWDATE:
	ans.append("DATE", 4);
	break;
      case FIELD_TYPE_SET:
	ans.append("SET", 3);
	break;
      case FIELD_TYPE_YEAR:
	ans.append("YEAR", 4);
	break;
      case FIELD_TYPE_TIME:
	ans.append("TIME", 4);
	break;
      case FIELD_TYPE_DECIMAL:
	ans.append("DECIMAL", 7);
	// if item is FIELD_ITEM, it _must_be_ Field_num in this case
	if (((Field_num*) ((Item_field*) (*f)->item)->field)->zerofill)
	  ans.append(" ZEROFILL");
	break;
      default:
	(*f)->get_opt_type(&ans, rows);
	break;
      }
    }
    if (!(*f)->nulls)
      ans.append(" NOT NULL");
    func_items[9]->set(ans.ptr(), ans.length());
    if (result->send_data(result_fields))
      return -1;
  }
  return 0;
} // analyse::end_of_records


void field_str::get_opt_type(String *answer, ha_rows total_rows)
{
  char buff[MAX_FIELD_WIDTH];

  if (can_be_still_num)
  {
    if (num_info.is_float)
      sprintf(buff, "DOUBLE");	  // number was like 1e+50... TODO:
    else if (num_info.decimals) // DOUBLE(%d,%d) sometime
    {
      if (num_info.dval > -FLT_MAX && num_info.dval < FLT_MAX)
	sprintf(buff, "FLOAT(%d,%d)", num_info.integers, num_info.decimals);
      else
	sprintf(buff, "DOUBLE(%d,%d)", num_info.integers, num_info.decimals);
    }
    else if (ev_num_info.llval >= -128 &&
	     ev_num_info.ullval <=
	     (ulonglong) (ev_num_info.llval >= 0 ? 255 : 127))
      sprintf(buff, "TINYINT(%d)", num_info.integers);
    else if (ev_num_info.llval >= INT_MIN16 &&
	     ev_num_info.ullval <= (ulonglong) (ev_num_info.llval >= 0 ?
						UINT_MAX16 : INT_MAX16))
      sprintf(buff, "SMALLINT(%d)", num_info.integers);
    else if (ev_num_info.llval >= INT_MIN24 &&
	     ev_num_info.ullval <= (ulonglong) (ev_num_info.llval >= 0 ?
						UINT_MAX24 : INT_MAX24))
      sprintf(buff, "MEDIUMINT(%d)", num_info.integers);
    else if (ev_num_info.llval >= INT_MIN32 &&
	     ev_num_info.ullval <= (ulonglong) (ev_num_info.llval >= 0 ?
						UINT_MAX32 : INT_MAX32))
      sprintf(buff, "INT(%d)", num_info.integers);
    else
      sprintf(buff, "BIGINT(%d)", num_info.integers);
    answer->append(buff, (uint) strlen(buff));
    if (ev_num_info.llval >= 0 && ev_num_info.min_dval >= 0)
      answer->append(" UNSIGNED");
    if (num_info.zerofill)
      answer->append(" ZEROFILL");
  }
  else if (max_length < 256)
  {
    if (must_be_blob)
    {
      if (item->binary)
	answer->append("TINYBLOB", 8);
      else
	answer->append("TINYTEXT", 8);
    }
    else if ((max_length * (total_rows - nulls)) < (sum + total_rows))
    {
      sprintf(buff, "CHAR(%d)", (int) max_length);
      answer->append(buff, (uint) strlen(buff));
    }
    else
    {
      sprintf(buff, "VARCHAR(%d)", (int) max_length);
      answer->append(buff, (uint) strlen(buff));
    }
  }
  else if (max_length < (1L << 16))
  {
    if (item->binary)
      answer->append("BLOB", 4);
    else
      answer->append("TEXT", 4);
  }
  else if (max_length < (1L << 24))
  {
    if (item->binary)
      answer->append("MEDIUMBLOB", 10);
    else
      answer->append("MEDIUMTEXT", 10);
  }
  else
  {
    if (item->binary)
      answer->append("LONGBLOB", 8);
    else
      answer->append("LONGTEXT", 8);
  }
} // field_str::get_opt_type


void field_real::get_opt_type(String *answer,
			      ha_rows total_rows __attribute__((unused)))
{
  char buff[MAX_FIELD_WIDTH];

  if (!max_notzero_dec_len)
  {
    if (min_arg >= -128 && max_arg <= (min_arg >= 0 ? 255 : 127))
      sprintf(buff, "TINYINT(%d)", (int) max_length - (item->decimals + 1));
    else if (min_arg >= INT_MIN16 && max_arg <= (min_arg >= 0 ?
						 UINT_MAX16 : INT_MAX16))
      sprintf(buff, "SMALLINT(%d)", (int) max_length - (item->decimals + 1));
    else if (min_arg >= INT_MIN24 && max_arg <= (min_arg >= 0 ?
						 UINT_MAX24 : INT_MAX24))
      sprintf(buff, "MEDIUMINT(%d)", (int) max_length - (item->decimals + 1));
    else if (min_arg >= INT_MIN32 && max_arg <= (min_arg >= 0 ?
						 UINT_MAX32 : INT_MAX32))
      sprintf(buff, "INT(%d)", (int) max_length - (item->decimals + 1));
    else
      sprintf(buff, "BIGINT(%d)", (int) max_length - (item->decimals + 1));
    answer->append(buff, (uint) strlen(buff));
    if (min_arg >= 0)
      answer->append(" UNSIGNED");
  }
  else if (item->decimals == NOT_FIXED_DEC)
  {
    if (min_arg >= -FLT_MAX && max_arg <= FLT_MAX)
      answer->append("FLOAT", 5);      
    else
      answer->append("DOUBLE", 6);
  }
  else
  {
    if (min_arg >= -FLT_MAX && max_arg <= FLT_MAX)
      sprintf(buff, "FLOAT(%d,%d)", (int) max_length - (item->decimals + 1),
	      max_notzero_dec_len);
    else
      sprintf(buff, "DOUBLE(%d,%d)", (int) max_length - (item->decimals + 1),
	      max_notzero_dec_len);
    answer->append(buff, (uint) strlen(buff));
  }
  // if item is FIELD_ITEM, it _must_be_ Field_num in this class
  if (item->type() == Item::FIELD_ITEM &&
      // a single number shouldn't be zerofill
      (max_length - (item->decimals + 1)) != 1 &&
      ((Field_num*) ((Item_field*) item)->field)->zerofill)
    answer->append(" ZEROFILL");
} // field_real::get_opt_type


void field_longlong::get_opt_type(String *answer,
				  ha_rows total_rows __attribute__((unused)))
{
  char buff[MAX_FIELD_WIDTH];

  if (min_arg >= -128 && max_arg <= (min_arg >= 0 ? 255 : 127))
    sprintf(buff, "TINYINT(%d)", (int) max_length);
  else if (min_arg >= INT_MIN16 && max_arg <= (min_arg >= 0 ?
					       UINT_MAX16 : INT_MAX16))
    sprintf(buff, "SMALLINT(%d)", (int) max_length);
  else if (min_arg >= INT_MIN24 && max_arg <= (min_arg >= 0 ?
					       UINT_MAX24 : INT_MAX24))
    sprintf(buff, "MEDIUMINT(%d)", (int) max_length);
  else if (min_arg >= INT_MIN32 && max_arg <= (min_arg >= 0 ?
					       UINT_MAX32 : INT_MAX32))
    sprintf(buff, "INT(%d)", (int) max_length);
  else
    sprintf(buff, "BIGINT(%d)", (int) max_length);
  answer->append(buff, (uint) strlen(buff));
  if (min_arg >= 0)
    answer->append(" UNSIGNED");

  // if item is FIELD_ITEM, it _must_be_ Field_num in this class
  if ((item->type() == Item::FIELD_ITEM) &&
      // a single number shouldn't be zerofill
      max_length != 1 &&
      ((Field_num*) ((Item_field*) item)->field)->zerofill)
    answer->append(" ZEROFILL");
} // field_longlong::get_opt_type


void field_ulonglong::get_opt_type(String *answer,
				   ha_rows total_rows __attribute__((unused)))
{
  char buff[MAX_FIELD_WIDTH];

  if (max_arg < 256)
    sprintf(buff, "TINYINT(%d) UNSIGNED", (int) max_length);
   else if (max_arg <= ((2 * INT_MAX16) + 1))
     sprintf(buff, "SMALLINT(%d) UNSIGNED", (int) max_length);
  else if (max_arg <= ((2 * INT_MAX24) + 1))
    sprintf(buff, "MEDIUMINT(%d) UNSIGNED", (int) max_length);
  else if (max_arg < (((ulonglong) 1) << 32))
    sprintf(buff, "INT(%d) UNSIGNED", (int) max_length);
  else
    sprintf(buff, "BIGINT(%d) UNSIGNED", (int) max_length);
  // if item is FIELD_ITEM, it _must_be_ Field_num in this class
  answer->append(buff, (uint) strlen(buff));
  if (item->type() == Item::FIELD_ITEM &&
      // a single number shouldn't be zerofill
      max_length != 1 &&
      ((Field_num*) ((Item_field*) item)->field)->zerofill)
    answer->append(" ZEROFILL");
} //field_ulonglong::get_opt_type


int collect_string(String *element,
		   element_count count __attribute__((unused)),
		   TREE_INFO *info)
{
  if (info->found)
    info->str->append(',');
  else
    info->found = 1;
  info->str->append('\'');
  info->str->append(*element);
  info->str->append('\'');
  return 0;
} // collect_string


int collect_real(double *element, element_count count __attribute__((unused)),
		 TREE_INFO *info)
{
  char buff[MAX_FIELD_WIDTH];
  String s(buff, sizeof(buff));

  if (info->found)
    info->str->append(',');
  else
    info->found = 1;
  info->str->append('\'');
  s.set(*element, info->item->decimals);
  info->str->append(s);
  info->str->append('\'');
  return 0;
} // collect_real


int collect_longlong(longlong *element,
		     element_count count __attribute__((unused)),
		     TREE_INFO *info)
{
  char buff[MAX_FIELD_WIDTH];
  String s(buff, sizeof(buff));

  if (info->found)
    info->str->append(',');
  else
    info->found = 1;
  info->str->append('\'');
  s.set(*element);
  info->str->append(s);
  info->str->append('\'');
  return 0;
} // collect_longlong


int collect_ulonglong(ulonglong *element,
		      element_count count __attribute__((unused)),
		      TREE_INFO *info)
{
  char buff[MAX_FIELD_WIDTH];
  String s(buff, sizeof(buff));

  if (info->found)
    info->str->append(',');
  else
    info->found = 1;
  info->str->append('\'');
  s.set(*element);
  info->str->append(s);
  info->str->append('\'');
  return 0;
} // collect_ulonglong


bool analyse::change_columns(List<Item> &field_list)
{
  field_list.empty();

  func_items[0] = new Item_proc_string("Field_name", 255);
  func_items[1] = new Item_proc_string("Min_value", 255);
  func_items[1]->maybe_null = 1;
  func_items[2] = new Item_proc_string("Max_value", 255);
  func_items[2]->maybe_null = 1;
  func_items[3] = new Item_proc_int("Min_length");
  func_items[4] = new Item_proc_int("Max_length");
  func_items[5] = new Item_proc_int("Empties_or_zeros");
  func_items[6] = new Item_proc_int("Nulls");
  func_items[7] = new Item_proc_string("Avg_value_or_avg_length", 255);
  func_items[8] = new Item_proc_string("Std", 255);
  func_items[8]->maybe_null = 1;
  func_items[9] = new Item_proc_string("Optimal_fieldtype",
				       max(64, output_str_length));

  for (uint i = 0; i < array_elements(func_items); i++)
    field_list.push_back(func_items[i]);
  result_fields = field_list;
  return 0;
} // analyse::change_columns

int compare_double(const double *s, const double *t)
{
  return ((*s < *t) ? -1 : *s > *t ? 1 : 0);
} /* compare_double */

int compare_longlong(const longlong *s, const longlong *t)
{
  return ((*s < *t) ? -1 : *s > *t ? 1 : 0);
} /* compare_longlong */

 int compare_ulonglong(const ulonglong *s, const ulonglong *t)
{
  return ((*s < *t) ? -1 : *s > *t ? 1 : 0);
} /* compare_ulonglong */


uint check_ulonglong(const char *str, uint length)
{
  const char *long_str = "2147483647", *ulonglong_str = "18446744073709551615";
  const uint long_len = 10, ulonglong_len = 20;

  while (*str == '0' && length)
  {
    str++; length--;
  }
  if (length < long_len)
    return NUM;

  uint smaller, bigger;
  const char *cmp;

  if (length == long_len)
  {
    cmp = long_str;
    smaller = NUM;
    bigger = LONG_NUM;
  }
  else if (length > ulonglong_len)
    return REAL_NUM;
  else
  {
    cmp = ulonglong_str;
    smaller = LONG_NUM;
    bigger = REAL_NUM;
  }
  while (*cmp && *cmp++ == *str++) ;
  return ((uchar) str[-1] <= (uchar) cmp[-1]) ? smaller : bigger;
} /* check_ulonlong */