item_sum.h

#ifndef ITEM_SUM_INCLUDED
#define ITEM_SUM_INCLUDED

/* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights
   reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */


/* classes for sum functions */

#include <my_tree.h>
#include "sql_udf.h"                            /* udf_handler */

class Item_sum;
class Aggregator_distinct;
class Aggregator_simple;

class Aggregator : public Sql_alloc
{
  friend class Item_sum;
  friend class Item_sum_sum;
  friend class Item_sum_count;
  friend class Item_sum_avg;

  /* 
    All members are protected as this class is not usable outside of an 
    Item_sum descendant.
  */
protected:
  /* the aggregate function class to act on */
  Item_sum *item_sum;

  bool use_distinct_values;

public:
  Aggregator (Item_sum *arg): item_sum(arg), use_distinct_values(FALSE) {}
  virtual ~Aggregator () {}                   /* Keep gcc happy */

  enum Aggregator_type { SIMPLE_AGGREGATOR, DISTINCT_AGGREGATOR }; 
  virtual Aggregator_type Aggrtype() = 0;

  virtual bool setup(THD *) = 0;

  virtual void clear() = 0;

  virtual bool add() = 0;

  virtual void endup() = 0;

  virtual my_decimal *arg_val_decimal(my_decimal * value) = 0;
  virtual double arg_val_real() = 0;
  virtual bool arg_is_null() = 0;
};


class st_select_lex;

class Item_sum :public Item_result_field
{
  friend class Aggregator_distinct;
  friend class Aggregator_simple;

protected:
  Aggregator *aggr;

private:
  bool force_copy_fields;

  bool with_distinct;

public:

  bool has_force_copy_fields() const { return force_copy_fields; }
  bool has_with_distinct()     const { return with_distinct; }

  enum Sumfunctype
  { COUNT_FUNC, COUNT_DISTINCT_FUNC, SUM_FUNC, SUM_DISTINCT_FUNC, AVG_FUNC,
    AVG_DISTINCT_FUNC, MIN_FUNC, MAX_FUNC, STD_FUNC,
    VARIANCE_FUNC, SUM_BIT_FUNC, UDF_SUM_FUNC, GROUP_CONCAT_FUNC
  };

  Item **ref_by; /* pointer to a ref to the object used to register it */
  Item_sum *next; /* next in the circular chain of registered objects  */
  Item_sum *in_sum_func;  /* embedding set function if any */ 
  st_select_lex * aggr_sel; /* select where the function is aggregated       */ 
  int8 nest_level;        /* number of the nesting level of the set function */
  int8 aggr_level;        /* nesting level of the aggregating subquery       */
  int8 max_arg_level;     /* max level of unbound column references          */
  int8 max_sum_func_level;/* max level of aggregation for embedded functions */
  bool quick_group;                     /* If incremental update of fields */
  /*
    This list is used by the check for mixing non aggregated fields and
    sum functions in the ONLY_FULL_GROUP_BY_MODE. We save all outer fields
    directly or indirectly used under this function it as it's unclear
    at the moment of fixing outer field whether it's aggregated or not.
  */
  List<Item_field> outer_fields;

protected:  
  uint arg_count;
  Item **args, *tmp_args[2];
  /* 
    Copy of the arguments list to hold the original set of arguments.
    Used in EXPLAIN EXTENDED instead of the current argument list because 
    the current argument list can be altered by usage of temporary tables.
  */
  Item **orig_args, *tmp_orig_args[2];
  table_map used_tables_cache;
  bool forced_const;
  static ulonglong ram_limitation(THD *thd);

public:  

  void mark_as_sum_func();
  Item_sum() :next(NULL), quick_group(1), arg_count(0), forced_const(FALSE)
  {
    mark_as_sum_func();
    init_aggregator();
  }
  Item_sum(Item *a) :next(NULL), quick_group(1), arg_count(1), args(tmp_args),
    orig_args(tmp_orig_args), forced_const(FALSE)
  {
    args[0]=a;
    mark_as_sum_func();
    init_aggregator();
  }
  Item_sum( Item *a, Item *b ) :next(NULL), quick_group(1), arg_count(2), args(tmp_args),
    orig_args(tmp_orig_args), forced_const(FALSE)
  {
    args[0]=a; args[1]=b;
    mark_as_sum_func();
    init_aggregator();
  }
  Item_sum(List<Item> &list);
  //Copy constructor, need to perform subselects with temporary tables
  Item_sum(THD *thd, Item_sum *item);
  enum Type type() const { return SUM_FUNC_ITEM; }
  virtual enum Sumfunctype sum_func () const=0;
  inline bool reset_and_add() 
  { 
    aggregator_clear(); 
    return aggregator_add(); 
  };

  /*
    Called when new group is started and results are being saved in
    a temporary table. Similarly to reset_and_add() it resets the 
    value to its default and aggregates the value of its 
    attribute(s), but must also store it in result_field. 
    This set of methods (result_item(), reset_field, update_field()) of
    Item_sum is used only if quick_group is not null. Otherwise
    copy_or_same() is used to obtain a copy of this item.
  */
  virtual void reset_field()=0;
  /*
    Called for each new value in the group, when temporary table is in use.
    Similar to add(), but uses temporary table field to obtain current value,
    Updated value is then saved in the field.
  */
  virtual void update_field()=0;
  virtual bool keep_field_type(void) const { return 0; }
  virtual void fix_length_and_dec() { maybe_null=1; null_value=1; }
  virtual Item *result_item(Field *field)
    { return new Item_field(field); }
  table_map used_tables() const { return used_tables_cache; }
  void update_used_tables ();
  bool is_null() { return null_value; }
  void make_const () 
  { 
    used_tables_cache= 0; 
    forced_const= TRUE; 
  }
  virtual bool const_item() const { return forced_const; }
  virtual bool const_during_execution() const { return false; }
  virtual void print(String *str, enum_query_type query_type);
  void fix_num_length_and_dec();

  virtual void no_rows_in_result()
  {
    set_aggregator(with_distinct ?
                   Aggregator::DISTINCT_AGGREGATOR :
                   Aggregator::SIMPLE_AGGREGATOR);
    aggregator_clear();
  }
  virtual void make_unique() { force_copy_fields= TRUE; }
  Item *get_tmp_table_item(THD *thd);
  virtual Field *create_tmp_field(bool group, TABLE *table);
  bool walk(Item_processor processor, bool walk_subquery, uchar *argument);
  virtual bool clean_up_after_removal(uchar *arg);
  bool init_sum_func_check(THD *thd);
  bool check_sum_func(THD *thd, Item **ref);
  bool register_sum_func(THD *thd, Item **ref);
  st_select_lex *depended_from() 
    { return (nest_level == aggr_level ? 0 : aggr_sel); }

  Item *get_arg(uint i) { return args[i]; }
  Item *set_arg(uint i, THD *thd, Item *new_val);
  uint get_arg_count() { return arg_count; }

  /* Initialization of distinct related members */
  void init_aggregator()
  {
    aggr= NULL;
    with_distinct= FALSE;
    force_copy_fields= FALSE;
  }

  inline bool aggregator_setup(THD *thd) { return aggr->setup(thd); };

  inline void aggregator_clear() { aggr->clear(); }

  inline bool aggregator_add() { return aggr->add(); };

  /* stores the declared DISTINCT flag (from the parser) */
  void set_distinct(bool distinct)
  {
    with_distinct= distinct;
    quick_group= with_distinct ? 0 : 1;
  }

  /*
    Set the type of aggregation : DISTINCT or not.

    May be called multiple times.
  */

  int set_aggregator(Aggregator::Aggregator_type aggregator);

  virtual void clear()= 0;
  virtual bool add()= 0;
  virtual bool setup(THD *thd) { return false; }

  virtual void cleanup();
};


class Unique;


class Aggregator_distinct : public Aggregator
{
  friend class Item_sum_sum;

  /* 
    flag to prevent consecutive runs of endup(). Normally in endup there are 
    expensive calculations (like walking the distinct tree for example) 
    which we must do only once if there are no data changes.
    We can re-use the data for the second and subsequent val_xxx() calls.
    endup_done set to TRUE also means that the calculated values for
    the aggregate functions are correct and don't need recalculation.
  */
  bool endup_done;

  /*
    Used depending on the type of the aggregate function and the presence of
    blob columns in it:
    - For COUNT(DISTINCT) and no blob fields this points to a real temporary
      table. It's used as a hash table.
    - For AVG/SUM(DISTINCT) or COUNT(DISTINCT) with blob fields only the
      in-memory data structure of a temporary table is constructed.
      It's used by the Field classes to transform data into row format.
  */
  TABLE *table;
  
  /*
    An array of field lengths on row allocated and used only for 
    COUNT(DISTINCT) with multiple columns and no blobs. Used in 
    Aggregator_distinct::composite_key_cmp (called from Unique to compare 
    nodes
  */
  uint32 *field_lengths;

  /*
    Used in conjunction with 'table' to support the access to Field classes 
    for COUNT(DISTINCT). Needed by copy_fields()/copy_funcs().
  */
  TMP_TABLE_PARAM *tmp_table_param;
  
  /*
    If there are no blobs in the COUNT(DISTINCT) arguments, we can use a tree,
    which is faster than heap table. In that case, we still use the table
    to help get things set up, but we insert nothing in it. 
    For AVG/SUM(DISTINCT) we always use this tree (as it takes a single 
    argument) to get the distinct rows.
  */
  Unique *tree;

  /* 
    The length of the temp table row. Must be a member of the class as it
    gets passed down to simple_raw_key_cmp () as a compare function argument
    to Unique. simple_raw_key_cmp () is used as a fast comparison function 
    when the entire row can be binary compared.
  */  
  uint tree_key_length;

  /* 
    Set to true if the result is known to be always NULL.
    If set deactivates creation and usage of the temporary table (in the 
    'table' member) and the Unique instance (in the 'tree' member) as well as 
    the calculation of the final value on the first call to 
    Item_[sum|avg|count]::val_xxx(). 
  */
  bool always_null;

public:
  Aggregator_distinct (Item_sum *sum) :
    Aggregator(sum), table(NULL), tmp_table_param(NULL), tree(NULL),
    always_null(FALSE) {}
  virtual ~Aggregator_distinct ();
  Aggregator_type Aggrtype() { return DISTINCT_AGGREGATOR; }

  bool setup(THD *);
  void clear(); 
  bool add();
  void endup();
  virtual my_decimal *arg_val_decimal(my_decimal * value);
  virtual double arg_val_real();
  virtual bool arg_is_null();

  bool unique_walk_function(void *element);
  static int composite_key_cmp(void* arg, uchar* key1, uchar* key2);
};


class Aggregator_simple : public Aggregator
{
public:

  Aggregator_simple (Item_sum *sum) :
    Aggregator(sum) {}
  Aggregator_type Aggrtype() { return Aggregator::SIMPLE_AGGREGATOR; }

  bool setup(THD * thd) { return item_sum->setup(thd); }
  void clear() { item_sum->clear(); }
  bool add() { return item_sum->add(); }
  void endup() {};
  virtual my_decimal *arg_val_decimal(my_decimal * value);
  virtual double arg_val_real();
  virtual bool arg_is_null();
};


class Item_sum_num :public Item_sum
{
protected:
  /*
   val_xxx() functions may be called several times during the execution of a 
   query. Derived classes that require extensive calculation in val_xxx()
   maintain cache of aggregate value. This variable governs the validity of 
   that cache.
  */
  bool is_evaluated;
public:
  Item_sum_num() :Item_sum(),is_evaluated(FALSE) {}
  Item_sum_num(Item *item_par) 
    :Item_sum(item_par), is_evaluated(FALSE) {}
  Item_sum_num(Item *a, Item* b) :Item_sum(a,b),is_evaluated(FALSE) {}
  Item_sum_num(List<Item> &list) 
    :Item_sum(list), is_evaluated(FALSE) {}
  Item_sum_num(THD *thd, Item_sum_num *item) 
    :Item_sum(thd, item),is_evaluated(item->is_evaluated) {}
  bool fix_fields(THD *, Item **);
  longlong val_int()
  {
    DBUG_ASSERT(fixed == 1);
    return (longlong) rint(val_real());             /* Real as default */
  }
  String *val_str(String*str);
  my_decimal *val_decimal(my_decimal *);
  bool get_date(MYSQL_TIME *ltime, uint fuzzydate)
  {
    return get_date_from_numeric(ltime, fuzzydate); /* Decimal or real */
  }
  bool get_time(MYSQL_TIME *ltime)
  {
    return get_time_from_numeric(ltime); /* Decimal or real */
  }
  void reset_field();
};


class Item_sum_int :public Item_sum_num
{
public:
  Item_sum_int(Item *item_par) :Item_sum_num(item_par) {}
  Item_sum_int(List<Item> &list) :Item_sum_num(list) {}
  Item_sum_int(THD *thd, Item_sum_int *item) :Item_sum_num(thd, item) {}
  double val_real() { DBUG_ASSERT(fixed == 1); return (double) val_int(); }
  String *val_str(String*str);
  my_decimal *val_decimal(my_decimal *);
  bool get_date(MYSQL_TIME *ltime, uint fuzzydate)
  {
    return get_date_from_int(ltime, fuzzydate);
  }
  bool get_time(MYSQL_TIME *ltime)
  {
    return get_time_from_int(ltime);
  }
  enum Item_result result_type () const { return INT_RESULT; }
  void fix_length_and_dec()
  { decimals=0; max_length=21; maybe_null=null_value=0; }
};


class Item_sum_sum :public Item_sum_num
{
protected:
  Item_result hybrid_type;
  double sum;
  my_decimal dec_buffs[2];
  uint curr_dec_buff;
  void fix_length_and_dec();

public:
  Item_sum_sum(Item *item_par, bool distinct) :Item_sum_num(item_par) 
  {
    set_distinct(distinct);
  }
  Item_sum_sum(THD *thd, Item_sum_sum *item);
  enum Sumfunctype sum_func () const 
  { 
    return has_with_distinct() ? SUM_DISTINCT_FUNC : SUM_FUNC; 
  }
  void clear();
  bool add();
  double val_real();
  longlong val_int();
  String *val_str(String*str);
  my_decimal *val_decimal(my_decimal *);
  enum Item_result result_type () const { return hybrid_type; }
  void reset_field();
  void update_field();
  void no_rows_in_result() {}
  const char *func_name() const 
  { 
    return has_with_distinct() ? "sum(distinct " : "sum("; 
  }
  Item *copy_or_same(THD* thd);
};


class Item_sum_count :public Item_sum_int
{
  longlong count;

  friend class Aggregator_distinct;

  void clear();
  bool add();
  void cleanup();

  public:
  Item_sum_count(Item *item_par)
    :Item_sum_int(item_par),count(0)
  {}

  Item_sum_count(List<Item> &list)
    :Item_sum_int(list),count(0)
  {
    set_distinct(TRUE);
  }
  Item_sum_count(THD *thd, Item_sum_count *item)
    :Item_sum_int(thd, item), count(item->count)
  {}
  enum Sumfunctype sum_func () const 
  { 
    return has_with_distinct() ? COUNT_DISTINCT_FUNC : COUNT_FUNC; 
  }
  void no_rows_in_result() { count=0; }
  void make_const(longlong count_arg) 
  { 
    count=count_arg;
    Item_sum::make_const();
  }
  longlong val_int();
  void reset_field();
  void update_field();
  const char *func_name() const 
  { 
    return has_with_distinct() ? "count(distinct " : "count(";
  }
  Item *copy_or_same(THD* thd);
};


/* Item to get the value of a stored sum function */

class Item_sum_avg;

class Item_sum_num_field: public Item_result_field
{
protected:
  Field *field;
  Item_result hybrid_type;
public:
  longlong val_int()
  {
    /* can't be fix_fields()ed */
    return (longlong) rint(val_real());
  }
  bool get_date(MYSQL_TIME *ltime, uint fuzzydate)
  {
    return get_date_from_numeric(ltime, fuzzydate); /* Decimal or real */
  }
  bool get_time(MYSQL_TIME *ltime)
  {
    return get_time_from_numeric(ltime); /* Decimal or real */
  }
  enum_field_types field_type() const
  {
    return hybrid_type == DECIMAL_RESULT ?
      MYSQL_TYPE_NEWDECIMAL : MYSQL_TYPE_DOUBLE;
  }
  enum Item_result result_type () const { return hybrid_type; }
  bool is_null() { update_null_value(); return null_value; }
};


class Item_avg_field :public Item_sum_num_field
{
public:
  uint f_precision, f_scale, dec_bin_size;
  uint prec_increment;
  Item_avg_field(Item_result res_type, Item_sum_avg *item);
  enum Type type() const { return FIELD_AVG_ITEM; }
  double val_real();
  my_decimal *val_decimal(my_decimal *);
  String *val_str(String*);
  void fix_length_and_dec() {}
  const char *func_name() const { DBUG_ASSERT(0); return "avg_field"; }
};


class Item_sum_avg :public Item_sum_sum
{
public:
  ulonglong count;
  uint prec_increment;
  uint f_precision, f_scale, dec_bin_size;
  Item_sum_avg(Item *item_par, bool distinct) 
    :Item_sum_sum(item_par, distinct), count(0) 
  {}
  Item_sum_avg(THD *thd, Item_sum_avg *item)
    :Item_sum_sum(thd, item), count(item->count),
    prec_increment(item->prec_increment) {}

  void fix_length_and_dec();
  enum Sumfunctype sum_func () const 
  {
    return has_with_distinct() ? AVG_DISTINCT_FUNC : AVG_FUNC;
  }
  void clear();
  bool add();
  double val_real();
  // In SPs we might force the "wrong" type with select into a declare variable
  longlong val_int() { return (longlong) rint(val_real()); }
  my_decimal *val_decimal(my_decimal *);
  String *val_str(String *str);
  void reset_field();
  void update_field();
  Item *result_item(Field *field)
  { return new Item_avg_field(hybrid_type, this); }
  void no_rows_in_result() {}
  const char *func_name() const 
  { 
    return has_with_distinct() ? "avg(distinct " : "avg("; 
  }
  Item *copy_or_same(THD* thd);
  Field *create_tmp_field(bool group, TABLE *table);
  void cleanup()
  {
    count= 0;
    Item_sum_sum::cleanup();
  }
};

class Item_sum_variance;

class Item_variance_field :public Item_sum_num_field
{
protected:
  uint f_precision0, f_scale0;
  uint f_precision1, f_scale1;
  uint dec_bin_size0, dec_bin_size1;
  uint sample;
  uint prec_increment;
public:
  Item_variance_field(Item_sum_variance *item);
  enum Type type() const {return FIELD_VARIANCE_ITEM; }
  double val_real();
  String *val_str(String *str)
  { return val_string_from_real(str); }
  my_decimal *val_decimal(my_decimal *dec_buf)
  { return val_decimal_from_real(dec_buf); }
  void fix_length_and_dec() {}
  const char *func_name() const { DBUG_ASSERT(0); return "variance_field"; }
};


/*
  variance(a) =

  =  sum (ai - avg(a))^2 / count(a) )
  =  sum (ai^2 - 2*ai*avg(a) + avg(a)^2) / count(a)
  =  (sum(ai^2) - sum(2*ai*avg(a)) + sum(avg(a)^2))/count(a) = 
  =  (sum(ai^2) - 2*avg(a)*sum(a) + count(a)*avg(a)^2)/count(a) = 
  =  (sum(ai^2) - 2*sum(a)*sum(a)/count(a) + count(a)*sum(a)^2/count(a)^2 )/count(a) = 
  =  (sum(ai^2) - 2*sum(a)^2/count(a) + sum(a)^2/count(a) )/count(a) = 
  =  (sum(ai^2) - sum(a)^2/count(a))/count(a)

But, this falls prey to catastrophic cancellation.  Instead, use the recurrence formulas

  M_{1} = x_{1}, ~ M_{k} = M_{k-1} + (x_{k} - M_{k-1}) / k newline 
  S_{1} = 0, ~ S_{k} = S_{k-1} + (x_{k} - M_{k-1}) times (x_{k} - M_{k}) newline
  for 2 <= k <= n newline
  ital variance = S_{n} / (n-1)

*/

class Item_sum_variance : public Item_sum_num
{
  void fix_length_and_dec();

public:
  Item_result hybrid_type;
  int cur_dec;
  double recurrence_m, recurrence_s;    /* Used in recurrence relation. */
  ulonglong count;
  uint f_precision0, f_scale0;
  uint f_precision1, f_scale1;
  uint dec_bin_size0, dec_bin_size1;
  uint sample;
  uint prec_increment;

  Item_sum_variance(Item *item_par, uint sample_arg) :Item_sum_num(item_par),
    hybrid_type(REAL_RESULT), count(0), sample(sample_arg)
    {}
  Item_sum_variance(THD *thd, Item_sum_variance *item);
  enum Sumfunctype sum_func () const { return VARIANCE_FUNC; }
  void clear();
  bool add();
  double val_real();
  my_decimal *val_decimal(my_decimal *);
  void reset_field();
  void update_field();
  Item *result_item(Field *field)
  { return new Item_variance_field(this); }
  void no_rows_in_result() {}
  const char *func_name() const
    { return sample ? "var_samp(" : "variance("; }
  Item *copy_or_same(THD* thd);
  Field *create_tmp_field(bool group, TABLE *table);
  enum Item_result result_type () const { return REAL_RESULT; }
  void cleanup()
  {
    count= 0;
    Item_sum_num::cleanup();
  }
};

class Item_sum_std;

class Item_std_field :public Item_variance_field
{
public:
  Item_std_field(Item_sum_std *item);
  enum Type type() const { return FIELD_STD_ITEM; }
  double val_real();
  my_decimal *val_decimal(my_decimal *);
  enum Item_result result_type () const { return REAL_RESULT; }
  enum_field_types field_type() const { return MYSQL_TYPE_DOUBLE;}
  const char *func_name() const { DBUG_ASSERT(0); return "std_field"; }
};

/*
   standard_deviation(a) = sqrt(variance(a))
*/

class Item_sum_std :public Item_sum_variance
{
  public:
  Item_sum_std(Item *item_par, uint sample_arg)
    :Item_sum_variance(item_par, sample_arg) {}
  Item_sum_std(THD *thd, Item_sum_std *item)
    :Item_sum_variance(thd, item)
    {}
  enum Sumfunctype sum_func () const { return STD_FUNC; }
  double val_real();
  Item *result_item(Field *field)
    { return new Item_std_field(this); }
  const char *func_name() const { return "std("; }
  Item *copy_or_same(THD* thd);
  enum Item_result result_type () const { return REAL_RESULT; }
  enum_field_types field_type() const { return MYSQL_TYPE_DOUBLE;}
};

// This class is a string or number function depending on num_func
class Arg_comparator;
class Item_cache;
class Item_sum_hybrid :public Item_sum
{
protected:
  Item_cache *value, *arg_cache;
  Arg_comparator *cmp;
  Item_result hybrid_type;
  enum_field_types hybrid_field_type;
  int cmp_sign;
  bool was_values;  // Set if we have found at least one row (for max/min only)

  public:
  Item_sum_hybrid(Item *item_par,int sign)
    :Item_sum(item_par), value(0), arg_cache(0), cmp(0),
    hybrid_type(INT_RESULT), hybrid_field_type(MYSQL_TYPE_LONGLONG),
    cmp_sign(sign), was_values(TRUE)
  { collation.set(&my_charset_bin); }
  Item_sum_hybrid(THD *thd, Item_sum_hybrid *item)
    :Item_sum(thd, item), value(item->value), arg_cache(0),
    hybrid_type(item->hybrid_type), hybrid_field_type(item->hybrid_field_type),
    cmp_sign(item->cmp_sign), was_values(item->was_values)
  { }
  bool fix_fields(THD *, Item **);
  void setup_hybrid(Item *item, Item *value_arg);
  void clear();
  double val_real();
  longlong val_int();
  longlong val_time_temporal();
  longlong val_date_temporal();
  my_decimal *val_decimal(my_decimal *);
  bool get_date(MYSQL_TIME *ltime, uint fuzzydate);
  bool get_time(MYSQL_TIME *ltime);
  void reset_field();
  String *val_str(String *);
  bool keep_field_type(void) const { return 1; }
  enum Item_result result_type () const { return hybrid_type; }
  enum enum_field_types field_type() const { return hybrid_field_type; }
  void update_field();
  void min_max_update_str_field();
  void min_max_update_temporal_field();
  void min_max_update_real_field();
  void min_max_update_int_field();
  void min_max_update_decimal_field();
  void cleanup();
  bool any_value() { return was_values; }
  void no_rows_in_result();
  Field *create_tmp_field(bool group, TABLE *table);
};


class Item_sum_min :public Item_sum_hybrid
{
public:
  Item_sum_min(Item *item_par) :Item_sum_hybrid(item_par,1) {}
  Item_sum_min(THD *thd, Item_sum_min *item) :Item_sum_hybrid(thd, item) {}
  enum Sumfunctype sum_func () const {return MIN_FUNC;}

  bool add();
  const char *func_name() const { return "min("; }
  Item *copy_or_same(THD* thd);
};


class Item_sum_max :public Item_sum_hybrid
{
public:
  Item_sum_max(Item *item_par) :Item_sum_hybrid(item_par,-1) {}
  Item_sum_max(THD *thd, Item_sum_max *item) :Item_sum_hybrid(thd, item) {}
  enum Sumfunctype sum_func () const {return MAX_FUNC;}

  bool add();
  const char *func_name() const { return "max("; }
  Item *copy_or_same(THD* thd);
};


class Item_sum_bit :public Item_sum_int
{
protected:
  ulonglong reset_bits,bits;

public:
  Item_sum_bit(Item *item_par,ulonglong reset_arg)
    :Item_sum_int(item_par),reset_bits(reset_arg),bits(reset_arg) {}
  Item_sum_bit(THD *thd, Item_sum_bit *item):
    Item_sum_int(thd, item), reset_bits(item->reset_bits), bits(item->bits) {}
  enum Sumfunctype sum_func () const {return SUM_BIT_FUNC;}
  void clear();
  longlong val_int();
  void reset_field();
  void update_field();
  void fix_length_and_dec()
  { decimals= 0; max_length=21; unsigned_flag= 1; maybe_null= null_value= 0; }
  void cleanup()
  {
    bits= reset_bits;
    Item_sum_int::cleanup();
  }
};


class Item_sum_or :public Item_sum_bit
{
public:
  Item_sum_or(Item *item_par) :Item_sum_bit(item_par,LL(0)) {}
  Item_sum_or(THD *thd, Item_sum_or *item) :Item_sum_bit(thd, item) {}
  bool add();
  const char *func_name() const { return "bit_or("; }
  Item *copy_or_same(THD* thd);
};


class Item_sum_and :public Item_sum_bit
{
  public:
  Item_sum_and(Item *item_par) :Item_sum_bit(item_par, ULONGLONG_MAX) {}
  Item_sum_and(THD *thd, Item_sum_and *item) :Item_sum_bit(thd, item) {}
  bool add();
  const char *func_name() const { return "bit_and("; }
  Item *copy_or_same(THD* thd);
};

class Item_sum_xor :public Item_sum_bit
{
  public:
  Item_sum_xor(Item *item_par) :Item_sum_bit(item_par,LL(0)) {}
  Item_sum_xor(THD *thd, Item_sum_xor *item) :Item_sum_bit(thd, item) {}
  bool add();
  const char *func_name() const { return "bit_xor("; }
  Item *copy_or_same(THD* thd);
};


/*
  User defined aggregates
*/

#ifdef HAVE_DLOPEN

class Item_udf_sum : public Item_sum
{
protected:
  udf_handler udf;

public:
  Item_udf_sum(udf_func *udf_arg)
    :Item_sum(), udf(udf_arg)
  { quick_group=0; }
  Item_udf_sum(udf_func *udf_arg, List<Item> &list)
    :Item_sum(list), udf(udf_arg)
  { quick_group=0;}
  Item_udf_sum(THD *thd, Item_udf_sum *item)
    :Item_sum(thd, item), udf(item->udf)
  { udf.not_original= TRUE; }
  const char *func_name() const { return udf.name(); }
  bool fix_fields(THD *thd, Item **ref)
  {
    DBUG_ASSERT(fixed == 0);

    if (init_sum_func_check(thd))
      return TRUE;

    fixed= 1;
    if (udf.fix_fields(thd, this, this->arg_count, this->args))
      return TRUE;

    memcpy (orig_args, args, sizeof (Item *) * arg_count);
    return check_sum_func(thd, ref);
  }
  enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
  virtual bool have_field_update(void) const { return 0; }

  void clear();
  bool add();
  void reset_field() {};
  void update_field() {};
  void cleanup();
  virtual void print(String *str, enum_query_type query_type);
};


class Item_sum_udf_float :public Item_udf_sum
{
 public:
  Item_sum_udf_float(udf_func *udf_arg)
    :Item_udf_sum(udf_arg) {}
  Item_sum_udf_float(udf_func *udf_arg, List<Item> &list)
    :Item_udf_sum(udf_arg, list) {}
  Item_sum_udf_float(THD *thd, Item_sum_udf_float *item)
    :Item_udf_sum(thd, item) {}
  longlong val_int()
  {
    DBUG_ASSERT(fixed == 1);
    return (longlong) rint(Item_sum_udf_float::val_real());
  }
  double val_real();
  String *val_str(String*str);
  my_decimal *val_decimal(my_decimal *);
  bool get_date(MYSQL_TIME *ltime, uint fuzzydate)
  {
    return get_date_from_real(ltime, fuzzydate);
  }
  bool get_time(MYSQL_TIME *ltime)
  {
    return get_time_from_real(ltime);
  }
  void fix_length_and_dec() { fix_num_length_and_dec(); }
  Item *copy_or_same(THD* thd);
};


class Item_sum_udf_int :public Item_udf_sum
{
public:
  Item_sum_udf_int(udf_func *udf_arg)
    :Item_udf_sum(udf_arg) {}
  Item_sum_udf_int(udf_func *udf_arg, List<Item> &list)
    :Item_udf_sum(udf_arg, list) {}
  Item_sum_udf_int(THD *thd, Item_sum_udf_int *item)
    :Item_udf_sum(thd, item) {}
  longlong val_int();
  double val_real()
    { DBUG_ASSERT(fixed == 1); return (double) Item_sum_udf_int::val_int(); }
  String *val_str(String*str);
  my_decimal *val_decimal(my_decimal *);
  bool get_date(MYSQL_TIME *ltime, uint fuzzydate)
  {
    return get_date_from_int(ltime, fuzzydate);
  }
  bool get_time(MYSQL_TIME *ltime)
  {
    return get_time_from_int(ltime);
  }
  enum Item_result result_type () const { return INT_RESULT; }
  void fix_length_and_dec() { decimals=0; max_length=21; }
  Item *copy_or_same(THD* thd);
};


class Item_sum_udf_str :public Item_udf_sum
{
public:
  Item_sum_udf_str(udf_func *udf_arg)
    :Item_udf_sum(udf_arg) {}
  Item_sum_udf_str(udf_func *udf_arg, List<Item> &list)
    :Item_udf_sum(udf_arg,list) {}
  Item_sum_udf_str(THD *thd, Item_sum_udf_str *item)
    :Item_udf_sum(thd, item) {}
  String *val_str(String *);
  double val_real()
  {
    int err_not_used;
    char *end_not_used;
    String *res;
    res=val_str(&str_value);
    return res ? my_strntod(res->charset(),(char*) res->ptr(),res->length(),
                            &end_not_used, &err_not_used) : 0.0;
  }
  longlong val_int()
  {
    int err_not_used;
    char *end;
    String *res;
    const CHARSET_INFO *cs;

    if (!(res= val_str(&str_value)))
      return 0;                                 /* Null value */
    cs= res->charset();
    end= (char*) res->ptr()+res->length();
    return cs->cset->strtoll10(cs, res->ptr(), &end, &err_not_used);
  }
  my_decimal *val_decimal(my_decimal *dec);
  bool get_date(MYSQL_TIME *ltime, uint fuzzydate)
  {
    return get_date_from_string(ltime, fuzzydate);
  }
  bool get_time(MYSQL_TIME *ltime)
  {
    return get_time_from_string(ltime);
  }
  enum Item_result result_type () const { return STRING_RESULT; }
  void fix_length_and_dec();
  Item *copy_or_same(THD* thd);
};


class Item_sum_udf_decimal :public Item_udf_sum
{
public:
  Item_sum_udf_decimal(udf_func *udf_arg)
    :Item_udf_sum(udf_arg) {}
  Item_sum_udf_decimal(udf_func *udf_arg, List<Item> &list)
    :Item_udf_sum(udf_arg, list) {}
  Item_sum_udf_decimal(THD *thd, Item_sum_udf_decimal *item)
    :Item_udf_sum(thd, item) {}
  String *val_str(String *);
  double val_real();
  longlong val_int();
  my_decimal *val_decimal(my_decimal *);
  bool get_date(MYSQL_TIME *ltime, uint fuzzydate)
  {
    return get_date_from_decimal(ltime, fuzzydate);
  }
  bool get_time(MYSQL_TIME *ltime)
  {
    return get_time_from_decimal(ltime);
  }
  enum Item_result result_type () const { return DECIMAL_RESULT; }
  void fix_length_and_dec() { fix_num_length_and_dec(); }
  Item *copy_or_same(THD* thd);
};

#else /* Dummy functions to get sql_yacc.cc compiled */

class Item_sum_udf_float :public Item_sum_num
{
 public:
  Item_sum_udf_float(udf_func *udf_arg)
    :Item_sum_num() {}
  Item_sum_udf_float(udf_func *udf_arg, List<Item> &list) :Item_sum_num() {}
  Item_sum_udf_float(THD *thd, Item_sum_udf_float *item)
    :Item_sum_num(thd, item) {}
  enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
  double val_real() { DBUG_ASSERT(fixed == 1); return 0.0; }
  void clear() {}
  bool add() { return 0; }  
  void update_field() {}
};


class Item_sum_udf_int :public Item_sum_num
{
public:
  Item_sum_udf_int(udf_func *udf_arg)
    :Item_sum_num() {}
  Item_sum_udf_int(udf_func *udf_arg, List<Item> &list) :Item_sum_num() {}
  Item_sum_udf_int(THD *thd, Item_sum_udf_int *item)
    :Item_sum_num(thd, item) {}
  enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
  longlong val_int() { DBUG_ASSERT(fixed == 1); return 0; }
  double val_real() { DBUG_ASSERT(fixed == 1); return 0; }
  void clear() {}
  bool add() { return 0; }  
  void update_field() {}
};


class Item_sum_udf_decimal :public Item_sum_num
{
 public:
  Item_sum_udf_decimal(udf_func *udf_arg)
    :Item_sum_num() {}
  Item_sum_udf_decimal(udf_func *udf_arg, List<Item> &list)
    :Item_sum_num() {}
  Item_sum_udf_decimal(THD *thd, Item_sum_udf_float *item)
    :Item_sum_num(thd, item) {}
  enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
  double val_real() { DBUG_ASSERT(fixed == 1); return 0.0; }
  my_decimal *val_decimal(my_decimal *) { DBUG_ASSERT(fixed == 1); return 0; }
  void clear() {}
  bool add() { return 0; }
  void update_field() {}
};


class Item_sum_udf_str :public Item_sum_num
{
public:
  Item_sum_udf_str(udf_func *udf_arg)
    :Item_sum_num() {}
  Item_sum_udf_str(udf_func *udf_arg, List<Item> &list)
    :Item_sum_num() {}
  Item_sum_udf_str(THD *thd, Item_sum_udf_str *item)
    :Item_sum_num(thd, item) {}
  String *val_str(String *)
    { DBUG_ASSERT(fixed == 1); null_value=1; return 0; }
  double val_real() { DBUG_ASSERT(fixed == 1); null_value=1; return 0.0; }
  longlong val_int() { DBUG_ASSERT(fixed == 1); null_value=1; return 0; }
  enum Item_result result_type () const { return STRING_RESULT; }
  void fix_length_and_dec() { maybe_null=1; max_length=0; }
  enum Sumfunctype sum_func () const { return UDF_SUM_FUNC; }
  void clear() {}
  bool add() { return 0; }  
  void update_field() {}
};

#endif /* HAVE_DLOPEN */

C_MODE_START
int group_concat_key_cmp_with_distinct(const void* arg, const void* key1,
                                       const void* key2);
int group_concat_key_cmp_with_order(const void* arg, const void* key1,
                                    const void* key2);
int dump_leaf_key(void* key_arg,
                  element_count count __attribute__((unused)),
                  void* item_arg);
C_MODE_END

class Item_func_group_concat : public Item_sum
{
  TMP_TABLE_PARAM *tmp_table_param;
  String result;
  String *separator;
  TREE tree_base;
  TREE *tree;

  Unique *unique_filter;
  TABLE *table;
  ORDER **order;
  Name_resolution_context *context;
  uint arg_count_order;
  uint arg_count_field;
  uint row_count;
  bool distinct;
  bool warning_for_row;
  bool always_null;
  bool force_copy_fields;
  bool no_appended;
  /*
    Following is 0 normal object and pointer to original one for copy
    (to correctly free resources)
  */
  Item_func_group_concat *original;

  friend int group_concat_key_cmp_with_distinct(const void* arg,
                                                const void* key1,
                                                const void* key2);
  friend int group_concat_key_cmp_with_order(const void* arg,
                                             const void* key1,
                                             const void* key2);
  friend int dump_leaf_key(void* key_arg,
                           element_count count __attribute__((unused)),
                           void* item_arg);

public:
  Item_func_group_concat(Name_resolution_context *context_arg,
                         bool is_distinct, List<Item> *is_select,
                         const SQL_I_List<ORDER> &is_order, String *is_separator);

  Item_func_group_concat(THD *thd, Item_func_group_concat *item);
  ~Item_func_group_concat();
  void cleanup();

  enum Sumfunctype sum_func () const {return GROUP_CONCAT_FUNC;}
  const char *func_name() const { return "group_concat"; }
  virtual Item_result result_type () const { return STRING_RESULT; }
  virtual Field *make_string_field(TABLE *table);
  enum_field_types field_type() const
  {
    if (max_length/collation.collation->mbmaxlen > CONVERT_IF_BIGGER_TO_BLOB )
      return MYSQL_TYPE_BLOB;
    else
      return MYSQL_TYPE_VARCHAR;
  }
  void clear();
  bool add();
  void reset_field() { DBUG_ASSERT(0); }        // not used
  void update_field() { DBUG_ASSERT(0); }       // not used
  bool fix_fields(THD *,Item **);
  bool setup(THD *thd);
  void make_unique();
  double val_real()
  {
    String *res;  res=val_str(&str_value);
    return res ? my_atof(res->c_ptr()) : 0.0;
  }
  longlong val_int()
  {
    String *res;
    char *end_ptr;
    int error;
    if (!(res= val_str(&str_value)))
      return (longlong) 0;
    end_ptr= (char*) res->ptr()+ res->length();
    return my_strtoll10(res->ptr(), &end_ptr, &error);
  }
  my_decimal *val_decimal(my_decimal *decimal_value)
  {
    return val_decimal_from_string(decimal_value);
  }
  bool get_date(MYSQL_TIME *ltime, uint fuzzydate)
  {
    return get_date_from_string(ltime, fuzzydate);
  }
  bool get_time(MYSQL_TIME *ltime)
  {
    return get_time_from_string(ltime);
  }
  String* val_str(String* str);
  Item *copy_or_same(THD* thd);
  void no_rows_in_result() {}
  virtual void print(String *str, enum_query_type query_type);
  virtual bool change_context_processor(uchar *cntx)
    { context= (Name_resolution_context *)cntx; return FALSE; }
};

#endif /* ITEM_SUM_INCLUDED */