mariadb/sql/item_sum.cc

/* Copyright (C) 2000-2003 MySQL 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 */


/* Sum functions (COUNT, MIN...) */

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

#include "mysql_priv.h"

Item_sum::Item_sum(List<Item> &list)
  :args_copy(0), arg_count(list.elements)
{
  if ((args=(Item**) sql_alloc(sizeof(Item*)*arg_count)))
  {
    uint i=0;
    List_iterator_fast<Item> li(list);
    Item *item;

    while ((item=li++))
    {
      args[i++]= item;
    }
  }
  mark_as_sum_func();
  list.empty();					// Fields are used
}


/*
  Constructor used in processing select with temporary tebles
*/

Item_sum::Item_sum(THD *thd, Item_sum *item):
  Item_result_field(thd, item), arg_count(item->arg_count),
  quick_group(item->quick_group)
{
  if (arg_count <= 2)
    args=tmp_args;
  else
    if (!(args= (Item**) thd->alloc(sizeof(Item*)*arg_count)))
      return;
  memcpy(args, item->args, sizeof(Item*)*arg_count);
  if (item->args_copy != 0)
    save_args(thd);
  else
    args_copy= 0;
}


/*
  Save copy of arguments if we are preparing a prepared statement
  (arguments can be rewritten in get_tmp_table_item())

  SYNOPSIS
    Item_sum::save_args_for_prepared_statement()
    thd		- thread handler

  RETURN
    0 - OK
    1 - Error
*/
bool Item_sum::save_args_for_prepared_statement(THD *thd)
{
  if (thd->current_arena->is_stmt_prepare() && args_copy == 0)
    return save_args(thd->current_arena);
  return 0;
}


bool Item_sum::save_args(Item_arena* arena)
{
  if (!(args_copy= (Item**) arena->alloc(sizeof(Item*)*arg_count)))
    return 1;
  memcpy(args_copy, args, sizeof(Item*)*arg_count);
  return 0;
}


void Item_sum::mark_as_sum_func()
{
  current_thd->lex->current_select->with_sum_func= 1;
  with_sum_func= 1;
}


void Item_sum::cleanup()
{
  DBUG_ENTER("Item_sum::cleanup");
  Item_result_field::cleanup();
  if (args_copy != 0)
    memcpy(args, args_copy, sizeof(Item*)*arg_count);
  result_field=0;
  DBUG_VOID_RETURN;
}


void Item_sum::make_field(Send_field *tmp_field)
{
  if (args[0]->type() == Item::FIELD_ITEM && keep_field_type())
  {
    ((Item_field*) args[0])->field->make_field(tmp_field);
    tmp_field->db_name=(char*)"";
    tmp_field->org_table_name=tmp_field->table_name=(char*)"";
    tmp_field->org_col_name=tmp_field->col_name=name;
    if (maybe_null)
      tmp_field->flags&= ~NOT_NULL_FLAG;
  }
  else
    init_make_field(tmp_field, field_type());
}


void Item_sum::print(String *str)
{
  str->append(func_name());
  str->append('(');
  for (uint i=0 ; i < arg_count ; i++)
  {
    if (i)
      str->append(',');
    args[i]->print(str);
  }
  str->append(')');
}

void Item_sum::fix_num_length_and_dec()
{
  decimals=0;
  for (uint i=0 ; i < arg_count ; i++)
    set_if_bigger(decimals,args[i]->decimals);
  max_length=float_length(decimals);
}

Item *Item_sum::get_tmp_table_item(THD *thd)
{
  Item_sum* sum_item= (Item_sum *) copy_or_same(thd);
  if (sum_item && sum_item->result_field)	   // If not a const sum func
  {
    Field *result_field_tmp= sum_item->result_field;
    for (uint i=0 ; i < sum_item->arg_count ; i++)
    {
      Item *arg= sum_item->args[i];
      if (!arg->const_item())
      {
	if (arg->type() == Item::FIELD_ITEM)
	  ((Item_field*) arg)->field= result_field_tmp++;
	else
	  sum_item->args[i]= new Item_field(result_field_tmp++);
      }
    }
  }
  return sum_item;
}

bool Item_sum::walk (Item_processor processor, byte *argument)
{
  if (arg_count)
  {
    Item **arg,**arg_end;
    for (arg= args, arg_end= args+arg_count; arg != arg_end; arg++)
    {
      if ((*arg)->walk(processor, argument))
	return 1;
    }
  }
  return (this->*processor)(argument);
}

String *
Item_sum_num::val_str(String *str)
{
  DBUG_ASSERT(fixed == 1);
  double nr=val();
  if (null_value)
    return 0;
  str->set(nr,decimals, &my_charset_bin);
  return str;
}


String *
Item_sum_int::val_str(String *str)
{
  DBUG_ASSERT(fixed == 1);
  longlong nr= val_int();
  if (null_value)
    return 0;
  if (unsigned_flag)
    str->set((ulonglong) nr, &my_charset_bin);
  else
    str->set(nr, &my_charset_bin);
  return str;
}


bool
Item_sum_num::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
{
  DBUG_ASSERT(fixed == 0);

  if (save_args_for_prepared_statement(thd))
    return 1;
  
  if (!thd->allow_sum_func)
  {
    my_error(ER_INVALID_GROUP_FUNC_USE,MYF(0));
    return 1;
  }
  thd->allow_sum_func=0;			// No included group funcs
  decimals=0;
  maybe_null=0;
  for (uint i=0 ; i < arg_count ; i++)
  {
    if (args[i]->fix_fields(thd, tables, args + i) || args[i]->check_cols(1))
      return 1;
    if (decimals < args[i]->decimals)
      decimals=args[i]->decimals;
    maybe_null |= args[i]->maybe_null;
  }
  result_field=0;
  max_length=float_length(decimals);
  null_value=1;
  fix_length_and_dec();
  thd->allow_sum_func=1;			// Allow group functions
  fixed= 1;
  return 0;
}


bool
Item_sum_hybrid::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
{
  DBUG_ASSERT(fixed == 0);

  if (save_args_for_prepared_statement(thd))
    return 1;

  Item *item= args[0];
  if (!thd->allow_sum_func)
  {
    my_error(ER_INVALID_GROUP_FUNC_USE,MYF(0));
    return 1;
  }
  thd->allow_sum_func=0;			// No included group funcs

  // 'item' can be changed during fix_fields
  if (!item->fixed &&
      item->fix_fields(thd, tables, args) ||
      (item= args[0])->check_cols(1))
    return 1;

  hybrid_type= item->result_type();
  if (hybrid_type == INT_RESULT)
  {
    cmp_charset= &my_charset_bin;
    max_length=20;
  }
  else if (hybrid_type == REAL_RESULT)
  {
    cmp_charset= &my_charset_bin;
    max_length=float_length(decimals);
  }else
  {
    cmp_charset= item->collation.collation;
    max_length=item->max_length;
  }
  decimals=item->decimals;
  /* MIN/MAX can return NULL for empty set indepedent of the used column */
  maybe_null= 1;
  unsigned_flag=item->unsigned_flag;
  collation.set(item->collation);
  result_field=0;
  null_value=1;
  fix_length_and_dec();
  thd->allow_sum_func=1;			// Allow group functions
  if (item->type() == Item::FIELD_ITEM)
    hybrid_field_type= ((Item_field*) item)->field->type();
  else
    hybrid_field_type= Item::field_type();
  fixed= 1;
  return 0;
}


/***********************************************************************
** reset and add of sum_func
***********************************************************************/

Item *Item_sum_sum::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_sum(thd, this);
}


void Item_sum_sum::clear()
{
  null_value=1; sum=0.0;
}


bool Item_sum_sum::add()
{
  sum+=args[0]->val();
  if (!args[0]->null_value)
    null_value= 0;
  return 0;
}


double Item_sum_sum::val()
{
  DBUG_ASSERT(fixed == 1);
  return sum;
}


/* Item_sum_sum_distinct */

Item_sum_sum_distinct::Item_sum_sum_distinct(Item *item)
  :Item_sum_num(item), sum(0.0), tree(0)
{
  /*
    quick_group is an optimizer hint, which means that GROUP BY can be
    handled with help of index on grouped columns.
    By setting quick_group to zero we force creation of temporary table
    to perform GROUP BY.
  */
  quick_group= 0;
}


Item_sum_sum_distinct::Item_sum_sum_distinct(THD *thd,
                                             Item_sum_sum_distinct *original)
  :Item_sum_num(thd, original), sum(0.0), tree(0)
{
  quick_group= 0;
}


Item_sum_sum_distinct::~Item_sum_sum_distinct()
{
  delete tree;
}
  

Item *
Item_sum_sum_distinct::copy_or_same(THD *thd)
{
  return new (&thd->mem_root) Item_sum_sum_distinct(thd, this);
}

C_MODE_START

static int simple_raw_key_cmp(void* arg, const void* key1, const void* key2)
{
  return memcmp(key1, key2, *(uint *) arg);
}

C_MODE_END

bool Item_sum_sum_distinct::setup(THD *thd)
{
  SELECT_LEX *select_lex= thd->lex->current_select;
  /* what does it mean??? */
  if (select_lex->linkage == GLOBAL_OPTIONS_TYPE)
    return 1;

  DBUG_ASSERT(tree == 0);                 /* setup can not be called twice */

  /*
    Uniques handles all unique elements in a tree until they can't fit in.
    Then thee tree is dumped to the temporary file.
    See class Unique for details.
  */
  null_value= maybe_null= 1;
  /*
    TODO: if underlying item result fits in 4 bytes we can take advantage
    of it and have tree of long/ulong. It gives 10% performance boost
  */
  static uint key_length= sizeof(double);
  tree= new Unique(simple_raw_key_cmp, &key_length, key_length,
                   thd->variables.max_heap_table_size);
  return tree == 0;
}

void Item_sum_sum_distinct::clear()
{
  DBUG_ASSERT(tree);                            /* we always have a tree */
  null_value= 1; 
  tree->reset();
}

bool Item_sum_sum_distinct::add()
{
  /* args[0]->val() may reset args[0]->null_value */
  double val= args[0]->val();
  if (!args[0]->null_value)
  {
    DBUG_ASSERT(tree);
    null_value= 0;
    if (val)
      return tree->unique_add(&val);
  }
  return 0;
}

C_MODE_START

static int sum_sum_distinct(void *element, element_count num_of_dups,
                     void *item_sum_sum_distinct)
{ 
  ((Item_sum_sum_distinct *)
   (item_sum_sum_distinct))->add(* (double *) element);
  return 0;
}

C_MODE_END

double Item_sum_sum_distinct::val()
{
  /*
    We don't have a tree only if 'setup()' hasn't been called;
    this is the case of sql_select.cc:return_zero_rows.
  */
  sum= 0.0;
  if (tree) 
    tree->walk(sum_sum_distinct, (void *) this);
  return sum;
}

/* end of Item_sum_sum_distinct */

Item *Item_sum_count::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_count(thd, this);
}


void Item_sum_count::clear()
{
  count= 0;
}


bool Item_sum_count::add()
{
  if (!args[0]->maybe_null)
    count++;
  else
  {
    (void) args[0]->val_int();
    if (!args[0]->null_value)
      count++;
  }
  return 0;
}

longlong Item_sum_count::val_int()
{
  DBUG_ASSERT(fixed == 1);
  return (longlong) count;
}


void Item_sum_count::cleanup()
{
  DBUG_ENTER("Item_sum_count::cleanup");
  Item_sum_int::cleanup();
  used_table_cache= ~(table_map) 0;
  DBUG_VOID_RETURN;
}


/*
  Avgerage
*/

Item *Item_sum_avg::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_avg(thd, this);
}


void Item_sum_avg::clear()
{
  sum=0.0; count=0;
}


bool Item_sum_avg::add()
{
  double nr=args[0]->val();
  if (!args[0]->null_value)
  {
    sum+=nr;
    count++;
  }
  return 0;
}

double Item_sum_avg::val()
{
  DBUG_ASSERT(fixed == 1);
  if (!count)
  {
    null_value=1;
    return 0.0;
  }
  null_value=0;
  return sum/ulonglong2double(count);
}


/*
  Standard deviation
*/

double Item_sum_std::val()
{
  DBUG_ASSERT(fixed == 1);
  double tmp= Item_sum_variance::val();
  return tmp <= 0.0 ? 0.0 : sqrt(tmp);
}

Item *Item_sum_std::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_std(thd, this);
}


/*
  Variance
*/

Item *Item_sum_variance::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_variance(thd, this);
}


void Item_sum_variance::clear()
{
  sum=sum_sqr=0.0; 
  count=0; 
}

bool Item_sum_variance::add()
{
  double nr=args[0]->val();
  if (!args[0]->null_value)
  {
    sum+=nr;
    sum_sqr+=nr*nr;
    count++;
  }
  return 0;
}

double Item_sum_variance::val()
{
  DBUG_ASSERT(fixed == 1);
  if (!count)
  {
    null_value=1;
    return 0.0;
  }
  null_value=0;
  /* Avoid problems when the precision isn't good enough */
  double tmp=ulonglong2double(count);
  double tmp2=(sum_sqr - sum*sum/tmp)/tmp;
  return tmp2 <= 0.0 ? 0.0 : tmp2;
}

void Item_sum_variance::reset_field()
{
  double nr=args[0]->val();
  char *res=result_field->ptr;

  if (args[0]->null_value)
    bzero(res,sizeof(double)*2+sizeof(longlong));
  else
  {
    float8store(res,nr);
    nr*=nr;
    float8store(res+sizeof(double),nr);
    longlong tmp=1;
    int8store(res+sizeof(double)*2,tmp);
  }
}

void Item_sum_variance::update_field()
{
  double nr,old_nr,old_sqr;
  longlong field_count;
  char *res=result_field->ptr;

  float8get(old_nr, res);
  float8get(old_sqr, res+sizeof(double));
  field_count=sint8korr(res+sizeof(double)*2);

  nr=args[0]->val();
  if (!args[0]->null_value)
  {
    old_nr+=nr;
    old_sqr+=nr*nr;
    field_count++;
  }
  float8store(res,old_nr);
  float8store(res+sizeof(double),old_sqr);
  int8store(res+sizeof(double)*2,field_count);
}

/* min & max */

void Item_sum_hybrid::clear()
{
  sum= 0.0;
  sum_int= 0;
  value.length(0);
  null_value= 1;
}

double Item_sum_hybrid::val()
{
  DBUG_ASSERT(fixed == 1);
  int err;
  if (null_value)
    return 0.0;
  switch (hybrid_type) {
  case STRING_RESULT:
    String *res;  res=val_str(&str_value);
    return (res ? my_strntod(res->charset(), (char*) res->ptr(),res->length(),
			     (char**) 0, &err) : 0.0);
  case INT_RESULT:
    if (unsigned_flag)
      return ulonglong2double(sum_int);
    return (double) sum_int;
  case REAL_RESULT:
    return sum;
  case ROW_RESULT:
  default:
    // This case should never be choosen
    DBUG_ASSERT(0);
    return 0;
  }
  return 0;					// Keep compiler happy
}

longlong Item_sum_hybrid::val_int()
{
  DBUG_ASSERT(fixed == 1);
  if (null_value)
    return 0;
  if (hybrid_type == INT_RESULT)
    return sum_int;
  return (longlong) Item_sum_hybrid::val();
}


String *
Item_sum_hybrid::val_str(String *str)
{
  DBUG_ASSERT(fixed == 1);
  if (null_value)
    return 0;
  switch (hybrid_type) {
  case STRING_RESULT:
    return &value;
  case REAL_RESULT:
    str->set(sum,decimals, &my_charset_bin);
    break;
  case INT_RESULT:
    if (unsigned_flag)
      str->set((ulonglong) sum_int, &my_charset_bin);
    else
      str->set((longlong) sum_int, &my_charset_bin);
    break;
  case ROW_RESULT:
  default:
    // This case should never be choosen
    DBUG_ASSERT(0);
    break;
  }
  return str;					// Keep compiler happy
}


void Item_sum_hybrid::cleanup()
{
  DBUG_ENTER("Item_sum_hybrid::cleanup");
  Item_sum::cleanup();
  used_table_cache= ~(table_map) 0;
  DBUG_VOID_RETURN;
}


Item *Item_sum_min::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_min(thd, this);
}


bool Item_sum_min::add()
{
  switch (hybrid_type) {
  case STRING_RESULT:
  {
    String *result=args[0]->val_str(&tmp_value);
    if (!args[0]->null_value &&
	(null_value || sortcmp(&value,result,cmp_charset) > 0))
    {
      value.copy(*result);
      null_value=0;
    }
  }
  break;
  case INT_RESULT:
  {
    longlong nr=args[0]->val_int();
    if (!args[0]->null_value && (null_value ||
				 (unsigned_flag && 
				  (ulonglong) nr < (ulonglong) sum_int) ||
				 (!unsigned_flag && nr < sum_int)))
    {
      sum_int=nr;
      null_value=0;
    }
  }
  break;
  case REAL_RESULT:
  {
    double nr=args[0]->val();
    if (!args[0]->null_value && (null_value || nr < sum))
    {
      sum=nr;
      null_value=0;
    }
  }
  break;
  case ROW_RESULT:
  default:
    // This case should never be choosen
    DBUG_ASSERT(0);
    break;
  }
  return 0;
}


Item *Item_sum_max::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_max(thd, this);
}


bool Item_sum_max::add()
{
  switch (hybrid_type) {
  case STRING_RESULT:
  {
    String *result=args[0]->val_str(&tmp_value);
    if (!args[0]->null_value &&
	(null_value || sortcmp(&value,result,cmp_charset) < 0))
    {
      value.copy(*result);
      null_value=0;
    }
  }
  break;
  case INT_RESULT:
  {
    longlong nr=args[0]->val_int();
    if (!args[0]->null_value && (null_value ||
				 (unsigned_flag && 
				  (ulonglong) nr > (ulonglong) sum_int) ||
				 (!unsigned_flag && nr > sum_int)))
    {
      sum_int=nr;
      null_value=0;
    }
  }
  break;
  case REAL_RESULT:
  {
    double nr=args[0]->val();
    if (!args[0]->null_value && (null_value || nr > sum))
    {
      sum=nr;
      null_value=0;
    }
  }
  break;
  case ROW_RESULT:
  default:
    // This case should never be choosen
    DBUG_ASSERT(0);
    break;
  }
  return 0;
}


/* bit_or and bit_and */

longlong Item_sum_bit::val_int()
{
  DBUG_ASSERT(fixed == 1);
  return (longlong) bits;
}


void Item_sum_bit::clear()
{
  bits= reset_bits;
}

Item *Item_sum_or::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_or(thd, this);
}


bool Item_sum_or::add()
{
  ulonglong value= (ulonglong) args[0]->val_int();
  if (!args[0]->null_value)
    bits|=value;
  return 0;
}

Item *Item_sum_xor::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_xor(thd, this);
}


bool Item_sum_xor::add()
{
  ulonglong value= (ulonglong) args[0]->val_int();
  if (!args[0]->null_value)
    bits^=value;
  return 0;
}

Item *Item_sum_and::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_and(thd, this);
}


bool Item_sum_and::add()
{
  ulonglong value= (ulonglong) args[0]->val_int();
  if (!args[0]->null_value)
    bits&=value;
  return 0;
}

/************************************************************************
** reset result of a Item_sum with is saved in a tmp_table
*************************************************************************/

void Item_sum_num::reset_field()
{
  double nr=args[0]->val();
  char *res=result_field->ptr;

  if (maybe_null)
  {
    if (args[0]->null_value)
    {
      nr=0.0;
      result_field->set_null();
    }
    else
      result_field->set_notnull();
  }
  float8store(res,nr);
}


void Item_sum_hybrid::reset_field()
{
  if (hybrid_type == STRING_RESULT)
  {
    char buff[MAX_FIELD_WIDTH];
    String tmp(buff,sizeof(buff),result_field->charset()),*res;

    res=args[0]->val_str(&tmp);
    if (args[0]->null_value)
    {
      result_field->set_null();
      result_field->reset();
    }
    else
    {
      result_field->set_notnull();
      result_field->store(res->ptr(),res->length(),tmp.charset());
    }
  }
  else if (hybrid_type == INT_RESULT)
  {
    longlong nr=args[0]->val_int();

    if (maybe_null)
    {
      if (args[0]->null_value)
      {
	nr=0;
	result_field->set_null();
      }
      else
	result_field->set_notnull();
    }
    result_field->store(nr);
  }
  else						// REAL_RESULT
  {
    double nr=args[0]->val();

    if (maybe_null)
    {
      if (args[0]->null_value)
      {
	nr=0.0;
	result_field->set_null();
      }
      else
	result_field->set_notnull();
    }
    result_field->store(nr);
  }
}


void Item_sum_sum::reset_field()
{
  double nr=args[0]->val();			// Nulls also return 0
  float8store(result_field->ptr,nr);
  if (args[0]->null_value)
    result_field->set_null();
  else
    result_field->set_notnull();
}


void Item_sum_count::reset_field()
{
  char *res=result_field->ptr;
  longlong nr=0;

  if (!args[0]->maybe_null)
    nr=1;
  else
  {
    (void) args[0]->val_int();
    if (!args[0]->null_value)
      nr=1;
  }
  int8store(res,nr);
}


void Item_sum_avg::reset_field()
{
  double nr=args[0]->val();
  char *res=result_field->ptr;

  if (args[0]->null_value)
    bzero(res,sizeof(double)+sizeof(longlong));
  else
  {
    float8store(res,nr);
    res+=sizeof(double);
    longlong tmp=1;
    int8store(res,tmp);
  }
}

void Item_sum_bit::reset_field()
{
  reset();
  int8store(result_field->ptr, bits);
}

void Item_sum_bit::update_field()
{
  char *res=result_field->ptr;
  bits= uint8korr(res);
  add();
  int8store(res, bits);
}

/*
** calc next value and merge it with field_value
*/

void Item_sum_sum::update_field()
{
  double old_nr,nr;
  char *res=result_field->ptr;

  float8get(old_nr,res);
  nr=args[0]->val();
  if (!args[0]->null_value)
  {
    old_nr+=nr;
    result_field->set_notnull();
  }
  float8store(res,old_nr);
}


void Item_sum_count::update_field()
{
  longlong nr;
  char *res=result_field->ptr;

  nr=sint8korr(res);
  if (!args[0]->maybe_null)
    nr++;
  else
  {
    (void) args[0]->val_int();
    if (!args[0]->null_value)
      nr++;
  }
  int8store(res,nr);
}


void Item_sum_avg::update_field()
{
  double nr,old_nr;
  longlong field_count;
  char *res=result_field->ptr;

  float8get(old_nr,res);
  field_count=sint8korr(res+sizeof(double));

  nr=args[0]->val();
  if (!args[0]->null_value)
  {
    old_nr+=nr;
    field_count++;
  }
  float8store(res,old_nr);
  res+=sizeof(double);
  int8store(res,field_count);
}

void Item_sum_hybrid::update_field()
{
  if (hybrid_type == STRING_RESULT)
    min_max_update_str_field();
  else if (hybrid_type == INT_RESULT)
    min_max_update_int_field();
  else
    min_max_update_real_field();
}


void
Item_sum_hybrid::min_max_update_str_field()
{
  String *res_str=args[0]->val_str(&value);

  if (!args[0]->null_value)
  {
    res_str->strip_sp();
    result_field->val_str(&tmp_value);

    if (result_field->is_null() ||
	(cmp_sign * sortcmp(res_str,&tmp_value,cmp_charset)) < 0)
      result_field->store(res_str->ptr(),res_str->length(),res_str->charset());
    result_field->set_notnull();
  }
}


void
Item_sum_hybrid::min_max_update_real_field()
{
  double nr,old_nr;

  old_nr=result_field->val_real();
  nr=args[0]->val();
  if (!args[0]->null_value)
  {
    if (result_field->is_null(0) ||
	(cmp_sign > 0 ? old_nr > nr : old_nr < nr))
      old_nr=nr;
    result_field->set_notnull();
  }
  else if (result_field->is_null(0))
    result_field->set_null();
  result_field->store(old_nr);
}


void
Item_sum_hybrid::min_max_update_int_field()
{
  longlong nr,old_nr;

  old_nr=result_field->val_int();
  nr=args[0]->val_int();
  if (!args[0]->null_value)
  {
    if (result_field->is_null(0))
      old_nr=nr;
    else
    {
      bool res=(unsigned_flag ?
		(ulonglong) old_nr > (ulonglong) nr :
		old_nr > nr);
      /* (cmp_sign > 0 && res) || (!(cmp_sign > 0) && !res) */
      if ((cmp_sign > 0) ^ (!res))
	old_nr=nr;
    }
    result_field->set_notnull();
  }
  else if (result_field->is_null(0))
    result_field->set_null();
  result_field->store(old_nr);
}


Item_avg_field::Item_avg_field(Item_sum_avg *item)
{
  name=item->name;
  decimals=item->decimals;
  max_length=item->max_length;
  field=item->result_field;
  maybe_null=1;
}


double Item_avg_field::val()
{
  // fix_fields() never calls for this Item
  double nr;
  longlong count;
  float8get(nr,field->ptr);
  char *res=(field->ptr+sizeof(double));
  count=sint8korr(res);

  if (!count)
  {
    null_value=1;
    return 0.0;
  }
  null_value=0;
  return nr/(double) count;
}

String *Item_avg_field::val_str(String *str)
{
  // fix_fields() never calls for this Item
  double nr=Item_avg_field::val();
  if (null_value)
    return 0;
  str->set(nr,decimals, &my_charset_bin);
  return str;
}

Item_std_field::Item_std_field(Item_sum_std *item)
  : Item_variance_field(item)
{
}

double Item_std_field::val()
{
  // fix_fields() never calls for this Item
  double tmp= Item_variance_field::val();
  return tmp <= 0.0 ? 0.0 : sqrt(tmp);
}

Item_variance_field::Item_variance_field(Item_sum_variance *item)
{
  name=item->name;
  decimals=item->decimals;
  max_length=item->max_length;
  field=item->result_field;
  maybe_null=1;
}

double Item_variance_field::val()
{
  // fix_fields() never calls for this Item
  double sum,sum_sqr;
  longlong count;
  float8get(sum,field->ptr);
  float8get(sum_sqr,(field->ptr+sizeof(double)));
  count=sint8korr(field->ptr+sizeof(double)*2);

  if (!count)
  {
    null_value=1;
    return 0.0;
  }
  null_value=0;
  double tmp= (double) count;
  double tmp2=(sum_sqr - sum*sum/tmp)/tmp;
  return tmp2 <= 0.0 ? 0.0 : tmp2;
}

String *Item_variance_field::val_str(String *str)
{
  // fix_fields() never calls for this Item
  double nr=val();
  if (null_value)
    return 0;
  str->set(nr,decimals, &my_charset_bin);
  return str;
}

/****************************************************************************
** COUNT(DISTINCT ...)
****************************************************************************/

#include "sql_select.h"

int simple_str_key_cmp(void* arg, byte* key1, byte* key2)
{
  Item_sum_count_distinct* item = (Item_sum_count_distinct*)arg;
  CHARSET_INFO *cs=item->key_charset;
  uint len=item->key_length;
  return cs->coll->strnncollsp(cs, 
			       (const uchar*) key1, len, 
			       (const uchar*) key2, len);
}

/*
  Did not make this one static - at least gcc gets confused when
  I try to declare a static function as a friend. If you can figure
  out the syntax to make a static function a friend, make this one
  static
*/

int composite_key_cmp(void* arg, byte* key1, byte* key2)
{
  Item_sum_count_distinct* item = (Item_sum_count_distinct*)arg;
  Field **field    = item->table->field;
  Field **field_end= field + item->table->fields;
  uint32 *lengths=item->field_lengths;
  for (; field < field_end; ++field)
  {
    Field* f = *field;
    int len = *lengths++;
    int res = f->key_cmp(key1, key2);
    if (res)
      return res;
    key1 += len;
    key2 += len;
  }
  return 0;
}

/*
  helper function for walking the tree when we dump it to MyISAM -
  tree_walk will call it for each leaf
*/

int dump_leaf(byte* key, uint32 count __attribute__((unused)),
		     Item_sum_count_distinct* item)
{
  byte* buf = item->table->record[0];
  int error;
  /*
    The first item->rec_offset bytes are taken care of with
    restore_record(table,default_values) in setup()
  */
  memcpy(buf + item->rec_offset, key, item->tree->size_of_element);
  if ((error = item->table->file->write_row(buf)))
  {
    if (error != HA_ERR_FOUND_DUPP_KEY &&
	error != HA_ERR_FOUND_DUPP_UNIQUE)
      return 1;
  }
  return 0;
}


void Item_sum_count_distinct::cleanup()
{
  DBUG_ENTER("Item_sum_count_distinct::cleanup");
  Item_sum_int::cleanup();
  /*
    Free table and tree if they belong to this item (if item have not pointer
    to original item from which was made copy => it own its objects )
  */
  if (!original)
  {
    if (table)
    {
      free_tmp_table(current_thd, table);
      table= 0;
    }
    delete tmp_table_param;
    tmp_table_param= 0;
    if (use_tree)
    {
      delete_tree(tree);
      use_tree= 0;
    }
  }
  DBUG_VOID_RETURN;
}


/* This is used by rollup to create a separate usable copy of the function */

void Item_sum_count_distinct::make_unique()
{
  table=0;
  original= 0;
  use_tree= 0; // to prevent delete_tree call on uninitialized tree
  tree= &tree_base;
}


bool Item_sum_count_distinct::setup(THD *thd)
{
  List<Item> list;
  SELECT_LEX *select_lex= thd->lex->current_select;
  if (select_lex->linkage == GLOBAL_OPTIONS_TYPE)
    return 1;
    
  if (!(tmp_table_param= new TMP_TABLE_PARAM))
    return 1;

  /* Create a table with an unique key over all parameters */
  for (uint i=0; i < arg_count ; i++)
  {
    Item *item=args[i];
    if (list.push_back(item))
      return 1;					// End of memory
    if (item->const_item())
    {
      (void) item->val_int();
      if (item->null_value)
	always_null=1;
    }
  }
  if (always_null)
    return 0;
  count_field_types(tmp_table_param,list,0);
  if (table)
  {
    free_tmp_table(thd, table);
    tmp_table_param->cleanup();
  }
  if (!(table= create_tmp_table(thd, tmp_table_param, list, (ORDER*) 0, 1,
				0,
				select_lex->options | thd->options,
				HA_POS_ERROR, (char*)"")))
    return 1;
  table->file->extra(HA_EXTRA_NO_ROWS);		// Don't update rows
  table->no_rows=1;


  // no blobs, otherwise it would be MyISAM
  if (table->db_type == DB_TYPE_HEAP)
  {
    qsort_cmp2 compare_key;
    void* cmp_arg;

    // to make things easier for dump_leaf if we ever have to dump to MyISAM
    restore_record(table,default_values);

    if (table->fields == 1)
    {
      /*
	If we have only one field, which is the most common use of
	count(distinct), it is much faster to use a simpler key
	compare method that can take advantage of not having to worry
	about other fields
      */
      Field* field = table->field[0];
      switch(field->type())
      {
      case FIELD_TYPE_STRING:
      case FIELD_TYPE_VAR_STRING:
	if (field->binary())
	{
	  compare_key = (qsort_cmp2)simple_raw_key_cmp;
	  cmp_arg = (void*) &key_length;
	}
	else
	{
	  /*
	    If we have a string, we must take care of charsets and case
	    sensitivity
	  */
	  compare_key = (qsort_cmp2)simple_str_key_cmp;
	  cmp_arg = (void*) this;
	}
	break;
      default:
	/*
	  Since at this point we cannot have blobs anything else can
	  be compared with memcmp
	*/
	compare_key = (qsort_cmp2)simple_raw_key_cmp;
	cmp_arg = (void*) &key_length;
	break;
      }
      key_charset = field->charset();
      key_length  = field->pack_length();
      rec_offset  = 1;
    }
    else // too bad, cannot cheat - there is more than one field
    {
      bool all_binary = 1;
      Field** field, **field_end;
      field_end = (field = table->field) + table->fields;
      uint32 *lengths;
      if (!(field_lengths= 
	    (uint32*) thd->alloc(sizeof(uint32) * table->fields)))
	return 1;

      for (key_length = 0, lengths=field_lengths; field < field_end; ++field)
      {
	uint32 length= (*field)->pack_length();
	key_length += length;
	*lengths++ = length;
	if (!(*field)->binary())
	  all_binary = 0;			// Can't break loop here
      }
      rec_offset = table->reclength - key_length;
      if (all_binary)
      {
	compare_key = (qsort_cmp2)simple_raw_key_cmp;
	cmp_arg = (void*) &key_length;
      }
      else
      {
	compare_key = (qsort_cmp2) composite_key_cmp ;
	cmp_arg = (void*) this;
      }
    }

    if (use_tree)
      delete_tree(tree);
    init_tree(tree, min(thd->variables.max_heap_table_size,
			thd->variables.sortbuff_size/16), 0,
	      key_length, compare_key, 0, NULL, cmp_arg);
    use_tree = 1;

    /*
      The only time key_length could be 0 is if someone does
      count(distinct) on a char(0) field - stupid thing to do,
      but this has to be handled - otherwise someone can crash
      the server with a DoS attack
    */
    max_elements_in_tree = ((key_length) ? 
			    thd->variables.max_heap_table_size/key_length : 1);

  }
  if (original)
  {
    original->table= table;
    original->use_tree= use_tree;
  }
  return 0;
}


int Item_sum_count_distinct::tree_to_myisam()
{
  if (create_myisam_from_heap(current_thd, table, tmp_table_param,
			      HA_ERR_RECORD_FILE_FULL, 1) ||
      tree_walk(tree, (tree_walk_action)&dump_leaf, (void*)this,
		left_root_right))
    return 1;
  delete_tree(tree);
  use_tree = 0;
  return 0;
}


Item *Item_sum_count_distinct::copy_or_same(THD* thd) 
{
  return new (&thd->mem_root) Item_sum_count_distinct(thd, this);
}


void Item_sum_count_distinct::clear()
{
  if (use_tree)
    reset_tree(tree);
  else if (table)
  {
    table->file->extra(HA_EXTRA_NO_CACHE);
    table->file->delete_all_rows();
    table->file->extra(HA_EXTRA_WRITE_CACHE);
  }
}

bool Item_sum_count_distinct::add()
{
  int error;
  if (always_null)
    return 0;
  copy_fields(tmp_table_param);
  copy_funcs(tmp_table_param->items_to_copy);

  for (Field **field=table->field ; *field ; field++)
    if ((*field)->is_real_null(0))
      return 0;					// Don't count NULL

  if (use_tree)
  {
    /*
      If the tree got too big, convert to MyISAM, otherwise insert into the
      tree.
    */
    if (tree->elements_in_tree > max_elements_in_tree)
    {
      if (tree_to_myisam())
	return 1;
    }
    else if (!tree_insert(tree, table->record[0] + rec_offset, 0,
			  tree->custom_arg))
      return 1;
  }
  else if ((error=table->file->write_row(table->record[0])))
  {
    if (error != HA_ERR_FOUND_DUPP_KEY &&
	error != HA_ERR_FOUND_DUPP_UNIQUE)
    {
      if (create_myisam_from_heap(current_thd, table, tmp_table_param, error,
				  1))
	return 1;				// Not a table_is_full error
    }
  }
  return 0;
}


longlong Item_sum_count_distinct::val_int()
{
  DBUG_ASSERT(fixed == 1);
  if (!table)					// Empty query
    return LL(0);
  if (use_tree)
    return tree->elements_in_tree;
  table->file->info(HA_STATUS_VARIABLE | HA_STATUS_NO_LOCK);
  return table->file->records;
}


void Item_sum_count_distinct::print(String *str)
{
  str->append("count(distinct ", 15);
  args[0]->print(str);
  str->append(')');
}

/****************************************************************************
** Functions to handle dynamic loadable aggregates
** Original source by: Alexis Mikhailov <root@medinf.chuvashia.su>
** Adapted for UDAs by: Andreas F. Bobak <bobak@relog.ch>.
** Rewritten by: Monty.
****************************************************************************/

#ifdef HAVE_DLOPEN

void Item_udf_sum::clear()
{
  DBUG_ENTER("Item_udf_sum::clear");
  udf.clear();
  DBUG_VOID_RETURN;
}

bool Item_udf_sum::add()
{
  DBUG_ENTER("Item_udf_sum::add");
  udf.add(&null_value);
  DBUG_RETURN(0);
}

Item *Item_sum_udf_float::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_udf_float(thd, this);
}

double Item_sum_udf_float::val()
{
  DBUG_ASSERT(fixed == 1);
  DBUG_ENTER("Item_sum_udf_float::val");
  DBUG_PRINT("info",("result_type: %d  arg_count: %d",
		     args[0]->result_type(), arg_count));
  DBUG_RETURN(udf.val(&null_value));
}

String *Item_sum_udf_float::val_str(String *str)
{
  DBUG_ASSERT(fixed == 1);
  double nr=val();
  if (null_value)
    return 0;					/* purecov: inspected */
  str->set(nr,decimals, &my_charset_bin);
  return str;
}


Item *Item_sum_udf_int::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_udf_int(thd, this);
}


longlong Item_sum_udf_int::val_int()
{
  DBUG_ASSERT(fixed == 1);
  DBUG_ENTER("Item_sum_udf_int::val_int");
  DBUG_PRINT("info",("result_type: %d  arg_count: %d",
		     args[0]->result_type(), arg_count));
  DBUG_RETURN(udf.val_int(&null_value));
}


String *Item_sum_udf_int::val_str(String *str)
{
  DBUG_ASSERT(fixed == 1);
  longlong nr=val_int();
  if (null_value)
    return 0;
  str->set(nr, &my_charset_bin);
  return str;
}

/* Default max_length is max argument length */

void Item_sum_udf_str::fix_length_and_dec()
{
  DBUG_ENTER("Item_sum_udf_str::fix_length_and_dec");
  max_length=0;
  for (uint i = 0; i < arg_count; i++)
    set_if_bigger(max_length,args[i]->max_length);
  DBUG_VOID_RETURN;
}


Item *Item_sum_udf_str::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_sum_udf_str(thd, this);
}


String *Item_sum_udf_str::val_str(String *str)
{
  DBUG_ASSERT(fixed == 1);
  DBUG_ENTER("Item_sum_udf_str::str");
  String *res=udf.val_str(str,&str_value);
  null_value = !res;
  DBUG_RETURN(res);
}

#endif /* HAVE_DLOPEN */


/*****************************************************************************
 GROUP_CONCAT function

 SQL SYNTAX:
  GROUP_CONCAT([DISTINCT] expr,... [ORDER BY col [ASC|DESC],...] 
    [SEPARATOR str_const])

 concat of values from "group by" operation

 BUGS
   DISTINCT and ORDER BY only works if ORDER BY uses all fields and only fields
   in expression list
   Blobs doesn't work with DISTINCT or ORDER BY
*****************************************************************************/

/*
  function of sort for syntax:
  GROUP_CONCAT(DISTINCT expr,...)
*/

int group_concat_key_cmp_with_distinct(void* arg, byte* key1,
				       byte* key2)
{
  Item_func_group_concat* grp_item= (Item_func_group_concat*)arg;
  Item **field_item, **end;
  char *record= (char*) grp_item->table->record[0];

  for (field_item= grp_item->args, end= field_item + grp_item->arg_count_field;
       field_item < end;
       field_item++)
  {
    /*
      We have to use get_tmp_table_field() instead of
      real_item()->get_tmp_table_field() because we want the field in
      the temporary table, not the original field
    */
    Field *field= (*field_item)->get_tmp_table_field();
    if (field)
    {
      int res;
      uint offset= (uint) (field->ptr - record);
      if ((res= field->key_cmp(key1 + offset, key2 + offset)))
	return res;
    }
  }
  return 0;
}


/*
  function of sort for syntax:
  GROUP_CONCAT(expr,... ORDER BY col,... )
*/

int group_concat_key_cmp_with_order(void* arg, byte* key1, byte* key2)
{
  Item_func_group_concat* grp_item= (Item_func_group_concat*) arg;
  ORDER **order_item, **end;
  char *record= (char*) grp_item->table->record[0];

  for (order_item= grp_item->order, end=order_item+ grp_item->arg_count_order;
       order_item < end;
       order_item++)
  {
    Item *item= *(*order_item)->item;
    /*
      We have to use get_tmp_table_field() instead of
      real_item()->get_tmp_table_field() because we want the field in
      the temporary table, not the original field
    */
    Field *field= item->get_tmp_table_field();
    if (field)
    {
      int res;
      uint offset= (uint) (field->ptr - record);
      if ((res= field->key_cmp(key1 + offset, key2 + offset)))
        return (*order_item)->asc ? res : -res;
    }
  }
  /*
    We can't return 0 because in that case the tree class would remove this
    item as double value. This would cause problems for case-changes and
    if the the returned values are not the same we do the sort on.
  */
  return 1;
}


/*
  function of sort for syntax:
  GROUP_CONCAT(DISTINCT expr,... ORDER BY col,... )

  BUG:
    This doesn't work in the case when the order by contains data that
    is not part of the field list because tree-insert will not notice
    the duplicated values when inserting things sorted by ORDER BY
*/

int group_concat_key_cmp_with_distinct_and_order(void* arg,byte* key1,
						 byte* key2)
{
  if (!group_concat_key_cmp_with_distinct(arg,key1,key2))
    return 0;
  return(group_concat_key_cmp_with_order(arg,key1,key2));
}


/*
  Append data from current leaf to item->result
*/

int dump_leaf_key(byte* key, uint32 count __attribute__((unused)),
                  Item_func_group_concat *item)
{
  char buff[MAX_FIELD_WIDTH];
  String tmp((char *)&buff,sizeof(buff),default_charset_info), tmp2;
  char *record= (char*) item->table->record[0];

  if (item->result.length())
    item->result.append(*item->separator);

  tmp.length(0);
  
  for (uint i= 0; i < item->arg_count_field; i++)
  {
    Item *show_item= item->args[i];
    if (!show_item->const_item())
    {
      /*
	We have to use get_tmp_table_field() instead of
	real_item()->get_tmp_table_field() because we want the field in
	the temporary table, not the original field
      */
      Field *field= show_item->get_tmp_table_field();
      String *res;
      char *save_ptr= field->ptr;
      uint offset= (uint) (save_ptr - record);
      DBUG_ASSERT(offset < item->table->reclength);
      field->ptr= (char *) key + offset;
      res= field->val_str(&tmp,&tmp2);
      item->result.append(*res);
      field->ptr= save_ptr;
    }
    else 
    {
      String *res= show_item->val_str(&tmp);
      if (res)
        item->result.append(*res);
    }
  }

  /* stop if length of result more than group_concat_max_len */  
  if (item->result.length() > item->group_concat_max_len)
  {
    item->count_cut_values++;
    item->result.length(item->group_concat_max_len);
    item->warning_for_row= TRUE;
    return 1;
  }
  return 0;
}


/*
  Constructor of Item_func_group_concat
  is_distinct - distinct
  is_select - list of expression for show values
  is_order - list of sort columns 
  is_separator - string value of separator
*/

Item_func_group_concat::Item_func_group_concat(bool is_distinct,
					       List<Item> *is_select,
					       SQL_LIST *is_order,
					       String *is_separator)
  :Item_sum(), tmp_table_param(0), max_elements_in_tree(0), warning(0),
   warning_available(0), key_length(0),
   tree_mode(0), distinct(is_distinct), warning_for_row(0),
   separator(is_separator), tree(&tree_base), table(0),
   order(0), tables_list(0),
   arg_count_order(0), arg_count_field(0),
   count_cut_values(0)
{
  Item *item_select;
  Item **arg_ptr;

  original= 0;
  quick_group= 0;
  mark_as_sum_func();
  order= 0;
  group_concat_max_len= current_thd->variables.group_concat_max_len;
    
  arg_count_field= is_select->elements;
  arg_count_order= is_order ? is_order->elements : 0;
  arg_count= arg_count_field + arg_count_order;
  
  /*
    We need to allocate:
    args - arg_count_field+arg_count_order
           (for possible order items in temporare tables)
    order - arg_count_order
  */
  if (!(args= (Item**) sql_alloc(sizeof(Item*) * arg_count +
				 sizeof(ORDER*)*arg_count_order)))
    return;

  order= (ORDER**)(args + arg_count);

  /* fill args items of show and sort */
  List_iterator_fast<Item> li(*is_select);

  for (arg_ptr=args ; (item_select= li++) ; arg_ptr++)
    *arg_ptr= item_select;

  if (arg_count_order) 
  {
    ORDER **order_ptr= order;
    for (ORDER *order_item= (ORDER*) is_order->first;
	 order_item != NULL;
	 order_item= order_item->next)
    {
      (*order_ptr++)= order_item;
      *arg_ptr= *order_item->item;
      order_item->item= arg_ptr++;
    }
  }
}
  

Item_func_group_concat::Item_func_group_concat(THD *thd,
					       Item_func_group_concat *item)
  :Item_sum(thd, item),item_thd(thd),
  tmp_table_param(item->tmp_table_param),
  max_elements_in_tree(item->max_elements_in_tree),
  warning(item->warning),
  warning_available(item->warning_available),
  key_length(item->key_length), 
  tree_mode(item->tree_mode),
  distinct(item->distinct),
  warning_for_row(item->warning_for_row),
  separator(item->separator),
  tree(item->tree),
  table(item->table),
  order(item->order),
  tables_list(item->tables_list),
  group_concat_max_len(item->group_concat_max_len),
  arg_count_order(item->arg_count_order),
  arg_count_field(item->arg_count_field),
  field_list_offset(item->field_list_offset),
  count_cut_values(item->count_cut_values),
  original(item)
{
  quick_group= item->quick_group;
}



void Item_func_group_concat::cleanup()
{
  DBUG_ENTER("Item_func_group_concat::cleanup");
  Item_sum::cleanup();

  /* fix order list */
  for (uint i= 0; i < arg_count_order ; i++)
    order[i]->item= &order[i]->item_ptr;

  /*
    Free table and tree if they belong to this item (if item have not pointer
    to original item from which was made copy => it own its objects )
  */
  if (!original)
  {
    THD *thd= current_thd;
    if (table)
    {
      free_tmp_table(thd, table);
      table= 0;
    }
    delete tmp_table_param;
    tmp_table_param= 0;
    if (tree_mode)
    {
      tree_mode= 0;
      delete_tree(tree); 
    }
  }
  DBUG_VOID_RETURN;
}


Item_func_group_concat::~Item_func_group_concat()
{
  /*
    Free table and tree if they belong to this item (if item have not pointer
    to original item from which was made copy => it own its objects )
  */
  if (!original)
  {
    if (warning_available)
    {
      char warn_buff[MYSQL_ERRMSG_SIZE];
      sprintf(warn_buff, ER(ER_CUT_VALUE_GROUP_CONCAT), count_cut_values);
      warning->set_msg(current_thd, warn_buff);
    }
  }
}


Item *Item_func_group_concat::copy_or_same(THD* thd)
{
  return new (&thd->mem_root) Item_func_group_concat(thd, this);
}


void Item_func_group_concat::clear()
{
  result.length(0);
  result.copy();
  null_value= TRUE;
  warning_for_row= FALSE;
  if (table)
  {
    table->file->extra(HA_EXTRA_NO_CACHE);
    table->file->delete_all_rows();
    table->file->extra(HA_EXTRA_WRITE_CACHE);
  }
  if (tree_mode)
    reset_tree(tree);
}


bool Item_func_group_concat::add()
{
  if (always_null)
    return 0;
  copy_fields(tmp_table_param);
  copy_funcs(tmp_table_param->items_to_copy);

  for (uint i= 0; i < arg_count_field; i++)
  {
    Item *show_item= args[i];
    if (!show_item->const_item())
    {
      /*
	Here we use real_item as we want the original field data that should
	be written to table->record[0]
      */
      Field *f= show_item->real_item()->get_tmp_table_field();
      if (f->is_null())
	return 0;				// Skip row if it contains null
    }
  }

  null_value= FALSE;
  if (tree_mode)
  {
    if (!tree_insert(tree, table->record[0], 0, tree->custom_arg))
      return 1;
  }
  else
  {
    if (result.length() <= group_concat_max_len && !warning_for_row)
      dump_leaf_key(table->record[0], 1, this);
  }
  return 0;
}


void Item_func_group_concat::reset_field()
{
  if (tree_mode)
    reset_tree(tree);
}


bool
Item_func_group_concat::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
{
  uint i;			/* for loop variable */ 
  DBUG_ASSERT(fixed == 0);

  if (save_args_for_prepared_statement(thd))
    return 1;

  if (!thd->allow_sum_func)
  {
    my_error(ER_INVALID_GROUP_FUNC_USE,MYF(0));
    return 1;
  }
  
  thd->allow_sum_func= 0;
  maybe_null= 0;
  item_thd= thd;

  /*
    Fix fields for select list and ORDER clause
  */

  for (i=0 ; i < arg_count ; i++)  
  {
    if (args[i]->fix_fields(thd, tables, args + i) || args[i]->check_cols(1))
      return 1;
    if (i < arg_count_field)
      maybe_null|= args[i]->maybe_null;
  }

  result_field= 0;
  null_value= 1;
  max_length= group_concat_max_len;
  thd->allow_sum_func= 1;
  if (!(tmp_table_param= new TMP_TABLE_PARAM))
    return 1;
  tables_list= tables;
  fixed= 1;
  return 0;
}


bool Item_func_group_concat::setup(THD *thd)
{
  List<Item> list;
  SELECT_LEX *select_lex= thd->lex->current_select;
  uint const_fields;
  qsort_cmp2 compare_key;
  DBUG_ENTER("Item_func_group_concat::setup");

  if (select_lex->linkage == GLOBAL_OPTIONS_TYPE)
    DBUG_RETURN(1);

  /*
    push all not constant fields to list and create temp table
  */
  const_fields= 0;
  always_null= 0;
  for (uint i= 0; i < arg_count_field; i++)
  {
    Item *item= args[i];
    if (list.push_back(item))
      DBUG_RETURN(1);
    if (item->const_item())
    {
      const_fields++;
      (void) item->val_int();
      if (item->null_value)
	always_null= 1;
    }
  }
  if (always_null)
    DBUG_RETURN(0);

  List<Item> all_fields(list);
  if (arg_count_order)
  {
    bool hidden_group_fields;
    setup_group(thd, args, tables_list, list, all_fields, *order,
                &hidden_group_fields);
  }

  count_field_types(tmp_table_param,all_fields,0);
  if (table)
  {
    /*
      We come here when we are getting the result from a temporary table,
      not the original tables used in the query
    */
    free_tmp_table(thd, table);
    tmp_table_param->cleanup();
  }
  /*
    We have to create a temporary table to get descriptions of fields 
    (types, sizes and so on).

    Note that in the table, we first have the ORDER BY fields, then the
    field list.

    We need to set set_sum_field in true for storing value of blob in buffer 
    of a record instead of a pointer of one. 
  */
  if (!(table=create_tmp_table(thd, tmp_table_param, all_fields, 
			       (ORDER*) 0, 0, TRUE,
                               select_lex->options | thd->options,
			       HA_POS_ERROR,(char *) "")))
    DBUG_RETURN(1);
  table->file->extra(HA_EXTRA_NO_ROWS);
  table->no_rows= 1;

  key_length= table->reclength;

  /* Offset to first result field in table */
  field_list_offset= table->fields - (list.elements - const_fields);

  if (tree_mode)
    delete_tree(tree);

  /* choose function of sort */  
  tree_mode= distinct || arg_count_order; 
  if (tree_mode)
  {
    if (arg_count_order)
    {
      if (distinct)
        compare_key= (qsort_cmp2) group_concat_key_cmp_with_distinct_and_order;
      else
        compare_key= (qsort_cmp2) group_concat_key_cmp_with_order;
    }
    else
    {
       compare_key= NULL;
      if (distinct)
        compare_key= (qsort_cmp2) group_concat_key_cmp_with_distinct;
    }
    /*
      Create a tree of sort. Tree is used for a sort and a remove double 
      values (according with syntax of the function). If function doesn't
      contain DISTINCT and ORDER BY clauses, we don't create this tree.
    */
    init_tree(tree, min(thd->variables.max_heap_table_size,
			thd->variables.sortbuff_size/16), 0,
              key_length, compare_key, 0, NULL, (void*) this);
    max_elements_in_tree= (key_length ? 
			   thd->variables.max_heap_table_size/key_length : 1);
  };

  /*
    Copy table and tree_mode if they belong to this item (if item have not 
    pointer to original item from which was made copy => it own its objects)
  */
  if (original)
  {
    original->table= table;
    original->tree_mode= tree_mode;
  }
  DBUG_RETURN(0);
}


/* This is used by rollup to create a separate usable copy of the function */

void Item_func_group_concat::make_unique()
{
  table=0;
  original= 0;
  tree_mode= 0; // to prevent delete_tree call on uninitialized tree
  tree= &tree_base;
}


String* Item_func_group_concat::val_str(String* str)
{
  DBUG_ASSERT(fixed == 1);
  if (null_value)
    return 0;
  if (tree_mode)
  {
    tree_walk(tree, (tree_walk_action)&dump_leaf_key, (void*)this,
              left_root_right);
  }
  if (count_cut_values && !warning_available)
  {
    warning_available= TRUE;
    warning= push_warning(item_thd, MYSQL_ERROR::WARN_LEVEL_WARN,
                           ER_CUT_VALUE_GROUP_CONCAT, NULL);
  }
  return &result;
}


void Item_func_group_concat::print(String *str)
{
  str->append("group_concat(", 13);
  if (distinct)
    str->append("distinct ", 9);
  for (uint i= 0; i < arg_count_field; i++)
  {
    if (i)
      str->append(',');
    args[i]->print(str);
  }
  if (arg_count_order)
  {
    str->append(" order by ", 10);
    for (uint i= 0 ; i < arg_count_order ; i++)
    {
      if (i)
	str->append(',');
      (*order[i]->item)->print(str);
    }
  }
  str->append(" separator \'", 12);
  str->append(*separator);
  str->append("\')", 2);
}