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Edit File : sql_statistics.h \| Size : 12.16 KB
/* Copyright 2006-2008 MySQL AB, 2008 Sun Microsystems, Inc. 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 02110-1335 USA / #ifndef SQL_STATISTICS_H #define SQL_STATISTICS_H / For COMPLEMENTARY_FOR_QUERIES and PREFERABLY_FOR_QUERIES they are similar to the COMPLEMENTARY and PREFERABLY respectively except that with these values we would not be collecting EITS for queries like ANALYZE TABLE t1; To collect EITS with these values, we have to use PERSISITENT FOR analyze table t1 persistent for columns (col1,col2...) index (idx1, idx2...) or analyze table t1 persistent for all / typedef enum enum_use_stat_tables_mode { NEVER, COMPLEMENTARY, PREFERABLY, COMPLEMENTARY_FOR_QUERIES, PREFERABLY_FOR_QUERIES } Use_stat_tables_mode; typedef enum enum_histogram_type { SINGLE_PREC_HB, DOUBLE_PREC_HB } Histogram_type; enum enum_stat_tables { TABLE_STAT, COLUMN_STAT, INDEX_STAT, }; / These enumeration types comprise the dictionary of three statistical tables table_stat, column_stat and index_stat as they defined in ../scripts/mysql_system_tables.sql. It would be nice if the declarations of these types were generated automatically by the table definitions. / enum enum_table_stat_col { TABLE_STAT_DB_NAME, TABLE_STAT_TABLE_NAME, TABLE_STAT_CARDINALITY, TABLE_STAT_N_FIELDS }; enum enum_column_stat_col { COLUMN_STAT_DB_NAME, COLUMN_STAT_TABLE_NAME, COLUMN_STAT_COLUMN_NAME, COLUMN_STAT_MIN_VALUE, COLUMN_STAT_MAX_VALUE, COLUMN_STAT_NULLS_RATIO, COLUMN_STAT_AVG_LENGTH, COLUMN_STAT_AVG_FREQUENCY, COLUMN_STAT_HIST_SIZE, COLUMN_STAT_HIST_TYPE, COLUMN_STAT_HISTOGRAM, COLUMN_STAT_N_FIELDS }; enum enum_index_stat_col { INDEX_STAT_DB_NAME, INDEX_STAT_TABLE_NAME, INDEX_STAT_INDEX_NAME, INDEX_STAT_PREFIX_ARITY, INDEX_STAT_AVG_FREQUENCY, INDEX_STAT_N_FIELDS }; inline Use_stat_tables_mode get_use_stat_tables_mode(THD thd) { return (Use_stat_tables_mode) (thd->variables.use_stat_tables); } inline bool check_eits_collection_allowed(THD thd) { return (get_use_stat_tables_mode(thd) == COMPLEMENTARY \|\| get_use_stat_tables_mode(thd) == PREFERABLY); } inline bool check_eits_preferred(THD thd) { return (get_use_stat_tables_mode(thd) == PREFERABLY \|\| get_use_stat_tables_mode(thd) == PREFERABLY_FOR_QUERIES); } int read_statistics_for_tables_if_needed(THD thd, TABLE_LIST tables); int read_statistics_for_tables(THD thd, TABLE_LIST tables, bool force_reload); int collect_statistics_for_table(THD thd, TABLE table); int alloc_statistics_for_table(THD thd, TABLE table, MY_BITMAP stat_fields); int update_statistics_for_table(THD thd, TABLE table); int delete_statistics_for_table(THD thd, const LEX_CSTRING db, const LEX_CSTRING tab); int delete_statistics_for_column(THD thd, TABLE tab, Field col); int delete_statistics_for_index(THD thd, TABLE tab, KEY key_info, bool ext_prefixes_only); int rename_table_in_stat_tables(THD thd, const LEX_CSTRING db, const LEX_CSTRING tab, const LEX_CSTRING new_db, const LEX_CSTRING new_tab); int rename_columns_in_stat_table(THD thd, TABLE tab, List<Alter_info::RENAME_COLUMN_STAT_PARAMS> fields); int rename_indexes_in_stat_table(THD thd, TABLE tab, List<Alter_info::RENAME_INDEX_STAT_PARAMS> indexes); void set_statistics_for_table(THD thd, TABLE table); double get_column_avg_frequency(Field field); double get_column_range_cardinality(Field field, key_range min_endp, key_range max_endp, uint range_flag); bool is_stat_table(const LEX_CSTRING db, LEX_CSTRING table); bool is_eits_usable(Field field); class Histogram { private: Histogram_type type; uint8 size; /* Size of values array, in bytes / uchar values; uint prec_factor() { switch (type) { case SINGLE_PREC_HB: return ((uint) (1 << 8) - 1); case DOUBLE_PREC_HB: return ((uint) (1 << 16) - 1); } return 1; } public: uint get_width() { switch (type) { case SINGLE_PREC_HB: return size; case DOUBLE_PREC_HB: return size / 2; } return 0; } private: uint get_value(uint i) { DBUG_ASSERT(i < get_width()); switch (type) { case SINGLE_PREC_HB: return (uint) (((uint8 ) values)[i]); case DOUBLE_PREC_HB: return (uint) uint2korr(values + i 2); } return 0; } /* Find the bucket which value 'pos' falls into. / uint find_bucket(double pos, bool first) { uint val= (uint) (pos prec_factor()); int lp= 0; int rp= get_width() - 1; int d= get_width() / 2; uint i= lp + d; for ( ; d; d= (rp - lp) / 2, i= lp + d) { if (val == get_value(i)) break; if (val < get_value(i)) rp= i; else if (val > get_value(i + 1)) lp= i + 1; else break; } if (val > get_value(i) && i < (get_width() - 1)) i++; if (val == get_value(i)) { if (first) { while(i && val == get_value(i - 1)) i--; } else { while(i + 1 < get_width() && val == get_value(i + 1)) i++; } } return i; } public: uint get_size() { return (uint) size; } Histogram_type get_type() { return type; } uchar get_values() { return (uchar ) values; } void set_size (ulonglong sz) { size= (uint8) sz; } void set_type (Histogram_type t) { type= t; } void set_values (uchar vals) { values= (uchar ) vals; } bool is_available() { return get_size() > 0 && get_values(); } /* This function checks that histograms should be usable only when 1) the level of optimizer_use_condition_selectivity > 3 2) histograms have been collected / bool is_usable(THD thd) { return thd->variables.optimizer_use_condition_selectivity > 3 && is_available(); } void set_value(uint i, double val) { switch (type) { case SINGLE_PREC_HB: ((uint8 ) values)[i]= (uint8) (val prec_factor()); return; case DOUBLE_PREC_HB: int2store(values + i * 2, val * prec_factor()); return; } } void set_prev_value(uint i) { switch (type) { case SINGLE_PREC_HB: ((uint8 ) values)[i]= ((uint8 ) values)[i-1]; return; case DOUBLE_PREC_HB: int2store(values + i * 2, uint2korr(values + i * 2 - 2)); return; } } double range_selectivity(double min_pos, double max_pos) { double sel; double bucket_sel= 1.0/(get_width() + 1); uint min= find_bucket(min_pos, TRUE); uint max= find_bucket(max_pos, FALSE); sel= bucket_sel * (max - min + 1); return sel; } /* Estimate selectivity of "col=const" using a histogram / double point_selectivity(double pos, double avg_sel); }; class Columns_statistics; class Index_statistics; / Statistical data on a table / class Table_statistics { public: my_bool cardinality_is_null; / TRUE if the cardinality is unknown / ha_rows cardinality; / Number of rows in the table / uchar min_max_record_buffers; /* Record buffers for min/max values / Column_statistics column_stats; /* Array of statistical data for columns / Index_statistics index_stats; /* Array of statistical data for indexes / / Array of records per key for index prefixes / ulonglong idx_avg_frequency; uchar histograms; / Sequence of histograms / }; / Statistical data on a column Note: objects of this class may be "empty", where they have almost all fields as zeros, for example, get_avg_frequency() will return 0. objects are allocated in alloc_statistics_for_table[_share]. / class Column_statistics { private: static const uint Scale_factor_nulls_ratio= 100000; static const uint Scale_factor_avg_length= 100000; static const uint Scale_factor_avg_frequency= 100000; public: / Bitmap indicating what statistical characteristics are available for the column / uint32 column_stat_nulls; / For the below two, see comments in get_column_range_cardinality() / / Minimum value for the column / Field min_value; /* Maximum value for the column / Field max_value; private: /* The ratio Z/N multiplied by the scale factor Scale_factor_nulls_ratio, where N is the total number of rows, Z is the number of nulls in the column / ulong nulls_ratio; / Average number of bytes occupied by the representation of a value of the column in memory buffers such as join buffer multiplied by the scale factor Scale_factor_avg_length. CHAR values are stripped of trailing spaces. Flexible values are stripped of their length prefixes. / ulonglong avg_length; / The ratio N/D multiplied by the scale factor Scale_factor_avg_frequency, where N is the number of rows with not null value in the column, D the number of distinct values among them / ulonglong avg_frequency; public: Histogram histogram; uint32 no_values_provided_bitmap() { return ((1 << (COLUMN_STAT_HISTOGRAM-COLUMN_STAT_COLUMN_NAME))-1) << (COLUMN_STAT_COLUMN_NAME+1); } void set_all_nulls() { column_stat_nulls= no_values_provided_bitmap(); } void set_not_null(uint stat_field_no) { column_stat_nulls&= ~(1 << stat_field_no); } bool is_null(uint stat_field_no) { return MY_TEST(column_stat_nulls & (1 << stat_field_no)); } double get_nulls_ratio() { return (double) nulls_ratio / Scale_factor_nulls_ratio; } double get_avg_length() { return (double) avg_length / Scale_factor_avg_length; } double get_avg_frequency() { return (double) avg_frequency / Scale_factor_avg_frequency; } void set_nulls_ratio (double val) { nulls_ratio= (ulong) (val Scale_factor_nulls_ratio); } void set_avg_length (double val) { avg_length= (ulonglong) (val * Scale_factor_avg_length); } void set_avg_frequency (double val) { avg_frequency= (ulonglong) (val * Scale_factor_avg_frequency); } bool min_max_values_are_provided() { return !is_null(COLUMN_STAT_MIN_VALUE) && !is_null(COLUMN_STAT_MAX_VALUE); } /* This function checks whether the values for the fields of the statistical tables that were NULL by DEFAULT for a column have changed or not. @retval TRUE: Statistics are not present for a column FALSE: Statisitics are present for a column / bool no_stat_values_provided() { return (column_stat_nulls == no_values_provided_bitmap()); } }; / Statistical data on an index prefixes / class Index_statistics { private: static const uint Scale_factor_avg_frequency= 100000; / The k-th element of this array contains the ratio N/D multiplied by the scale factor Scale_factor_avg_frequency, where N is the number of index entries without nulls in the first k components, and D is the number of distinct k-component prefixes among them / ulonglong avg_frequency; public: void init_avg_frequency(ulonglong ptr) { avg_frequency= ptr; } bool avg_frequency_is_inited() { return avg_frequency != NULL; } double get_avg_frequency(uint i) const { return (double) avg_frequency[i] / Scale_factor_avg_frequency; } void set_avg_frequency(uint i, double val) { avg_frequency[i]= (ulonglong) (val Scale_factor_avg_frequency); } }; #endif /* SQL_STATISTICS_H */ Back

Edit File : sql_statistics.h | Size : 12.16 KB

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  02110-1335  USA */

#ifndef SQL_STATISTICS_H
#define SQL_STATISTICS_H

/*
  For COMPLEMENTARY_FOR_QUERIES and PREFERABLY_FOR_QUERIES they are
  similar to the COMPLEMENTARY and PREFERABLY respectively except that
  with these values we would not be collecting EITS for queries like
    ANALYZE TABLE t1;
  To collect EITS with these values, we have to use PERSISITENT FOR
  analyze table t1 persistent for
     columns (col1,col2...) index (idx1, idx2...)
     or
  analyze table t1 persistent for all
*/

typedef
enum enum_use_stat_tables_mode
{
  NEVER,
  COMPLEMENTARY,
  PREFERABLY,
  COMPLEMENTARY_FOR_QUERIES,
  PREFERABLY_FOR_QUERIES
} Use_stat_tables_mode;

typedef
enum enum_histogram_type
{
  SINGLE_PREC_HB,
  DOUBLE_PREC_HB
} Histogram_type;

enum enum_stat_tables
{
  TABLE_STAT,
  COLUMN_STAT,
  INDEX_STAT,
};

/* 
  These enumeration types comprise the dictionary of three
  statistical tables table_stat, column_stat and index_stat
  as they defined in ../scripts/mysql_system_tables.sql.

It would be nice if the declarations of these types were
  generated automatically by the table definitions.   
*/

enum enum_table_stat_col
{
  TABLE_STAT_DB_NAME,
  TABLE_STAT_TABLE_NAME,
  TABLE_STAT_CARDINALITY,
  TABLE_STAT_N_FIELDS
};

enum enum_column_stat_col
{
  COLUMN_STAT_DB_NAME,
  COLUMN_STAT_TABLE_NAME,
  COLUMN_STAT_COLUMN_NAME,
  COLUMN_STAT_MIN_VALUE,
  COLUMN_STAT_MAX_VALUE,
  COLUMN_STAT_NULLS_RATIO,
  COLUMN_STAT_AVG_LENGTH,
  COLUMN_STAT_AVG_FREQUENCY,
  COLUMN_STAT_HIST_SIZE,
  COLUMN_STAT_HIST_TYPE,
  COLUMN_STAT_HISTOGRAM,
  COLUMN_STAT_N_FIELDS
};

enum enum_index_stat_col
{
  INDEX_STAT_DB_NAME,
  INDEX_STAT_TABLE_NAME,
  INDEX_STAT_INDEX_NAME,
  INDEX_STAT_PREFIX_ARITY,
  INDEX_STAT_AVG_FREQUENCY,
  INDEX_STAT_N_FIELDS
};

inline
Use_stat_tables_mode get_use_stat_tables_mode(THD *thd)
{ 
  return (Use_stat_tables_mode) (thd->variables.use_stat_tables);
}
inline
bool check_eits_collection_allowed(THD *thd)
{
  return (get_use_stat_tables_mode(thd) == COMPLEMENTARY ||
          get_use_stat_tables_mode(thd) == PREFERABLY);
}

inline
bool check_eits_preferred(THD *thd)
{
  return (get_use_stat_tables_mode(thd) == PREFERABLY ||
          get_use_stat_tables_mode(thd) == PREFERABLY_FOR_QUERIES);
}

int read_statistics_for_tables_if_needed(THD *thd, TABLE_LIST *tables);
int read_statistics_for_tables(THD *thd, TABLE_LIST *tables,
                               bool force_reload);
int collect_statistics_for_table(THD *thd, TABLE *table);
int alloc_statistics_for_table(THD *thd, TABLE *table, MY_BITMAP *stat_fields);
int update_statistics_for_table(THD *thd, TABLE *table);
int delete_statistics_for_table(THD *thd, const LEX_CSTRING *db,
                                const LEX_CSTRING *tab);
int delete_statistics_for_column(THD *thd, TABLE *tab, Field *col);
int delete_statistics_for_index(THD *thd, TABLE *tab, KEY *key_info,
                                bool ext_prefixes_only);
int rename_table_in_stat_tables(THD *thd, const LEX_CSTRING *db,
                                const LEX_CSTRING *tab,
                                const LEX_CSTRING *new_db,
                                const LEX_CSTRING *new_tab);
int rename_columns_in_stat_table(THD *thd, TABLE *tab,
                                 List<Alter_info::RENAME_COLUMN_STAT_PARAMS> *fields);
int rename_indexes_in_stat_table(THD *thd, TABLE *tab,
                                 List<Alter_info::RENAME_INDEX_STAT_PARAMS> *indexes);
void set_statistics_for_table(THD *thd, TABLE *table);

double get_column_avg_frequency(Field * field);

double get_column_range_cardinality(Field *field,
                                    key_range *min_endp,
                                    key_range *max_endp,
                                    uint range_flag);
bool is_stat_table(const LEX_CSTRING *db, LEX_CSTRING *table);
bool is_eits_usable(Field* field);

class Histogram
{

private:
  Histogram_type type;
  uint8 size; /* Size of values array, in bytes */
  uchar *values;

uint prec_factor()
  {
    switch (type) {
    case SINGLE_PREC_HB:
      return ((uint) (1 << 8) - 1);
    case DOUBLE_PREC_HB:
      return ((uint) (1 << 16) - 1);
    }
    return 1;
  }

public:
  uint get_width()
  {
    switch (type) {
    case SINGLE_PREC_HB:
      return size;
    case DOUBLE_PREC_HB:
      return size / 2;
    }
    return 0;
  }

private:
  uint get_value(uint i)
  {
    DBUG_ASSERT(i < get_width());
    switch (type) {
    case SINGLE_PREC_HB:
      return (uint) (((uint8 *) values)[i]);
    case DOUBLE_PREC_HB:
      return (uint) uint2korr(values + i * 2);
    }
    return 0;
  }

/* Find the bucket which value 'pos' falls into. */
  uint find_bucket(double pos, bool first)
  {
    uint val= (uint) (pos * prec_factor());
    int lp= 0;
    int rp= get_width() - 1;
    int d= get_width() / 2;
    uint i= lp + d;
    for ( ; d;  d= (rp - lp) / 2, i= lp + d)
    {
      if (val == get_value(i))
	break; 
      if (val < get_value(i))
        rp= i;
      else if (val > get_value(i + 1))
        lp= i + 1;
      else
        break;
    }

if (val > get_value(i) && i < (get_width() - 1))
      i++;

if (val == get_value(i))
    {
      if (first)
      {
        while(i && val == get_value(i - 1))
          i--;
      }
      else
      {
        while(i + 1 < get_width() && val == get_value(i + 1))
          i++;
      }
    }
    return i;
  }

public:

uint get_size() { return (uint) size; }

Histogram_type get_type() { return type; }

uchar *get_values() { return (uchar *) values; }

void set_size (ulonglong sz) { size= (uint8) sz; }

void set_type (Histogram_type t) { type= t; }

void set_values (uchar *vals) { values= (uchar *) vals; }

bool is_available() { return get_size() > 0 && get_values(); }

/*
    This function checks that histograms should be usable only when
      1) the level of optimizer_use_condition_selectivity > 3
      2) histograms have been collected
  */
  bool is_usable(THD *thd)
  {
    return thd->variables.optimizer_use_condition_selectivity > 3 &&
           is_available();
  }

void set_value(uint i, double val)
  {
    switch (type) {
    case SINGLE_PREC_HB:   
      ((uint8 *) values)[i]= (uint8) (val * prec_factor());
      return;
    case DOUBLE_PREC_HB:
      int2store(values + i * 2, val * prec_factor());
      return;
    }
  }

void set_prev_value(uint i)
  {
    switch (type) {
    case SINGLE_PREC_HB:   
      ((uint8 *) values)[i]= ((uint8 *) values)[i-1];
      return;
    case DOUBLE_PREC_HB:
      int2store(values + i * 2, uint2korr(values + i * 2 - 2));
      return;
    }
  }

double range_selectivity(double min_pos, double max_pos)
  {
    double sel;
    double bucket_sel= 1.0/(get_width() + 1);  
    uint min= find_bucket(min_pos, TRUE);
    uint max= find_bucket(max_pos, FALSE);
    sel= bucket_sel * (max - min + 1);
    return sel;
  } 
  
  /*
    Estimate selectivity of "col=const" using a histogram
  */
  double point_selectivity(double pos, double avg_sel);
};

class Columns_statistics;
class Index_statistics;

/* Statistical data on a table */

class Table_statistics
{

public:
  my_bool cardinality_is_null;      /* TRUE if the cardinality is unknown */
  ha_rows cardinality;              /* Number of rows in the table        */
  uchar *min_max_record_buffers;    /* Record buffers for min/max values  */
  Column_statistics *column_stats;  /* Array of statistical data for columns */
  Index_statistics *index_stats;    /* Array of statistical data for indexes */

/* Array of records per key for index prefixes */
  ulonglong *idx_avg_frequency;
  uchar *histograms;                /* Sequence of histograms */
};

/* 
  Statistical data on a column

Note: objects of this class may be "empty", where they have almost all fields
  as zeros, for example, get_avg_frequency() will return 0.

objects are allocated in alloc_statistics_for_table[_share].
*/

class Column_statistics
{

private:
  static const uint Scale_factor_nulls_ratio= 100000;
  static const uint Scale_factor_avg_length= 100000;
  static const uint Scale_factor_avg_frequency= 100000;

public:
  /* 
    Bitmap indicating  what statistical characteristics
    are available for the column
  */
  uint32 column_stat_nulls;
  
  /* For the below two, see comments in get_column_range_cardinality() */
  /* Minimum value for the column */
  Field *min_value; 
  /* Maximum value for the column */   
  Field *max_value;

private:

/* 
    The ratio Z/N multiplied by the scale factor Scale_factor_nulls_ratio,
    where 
      N is the total number of rows,
      Z is the number of nulls in the column
  */
  ulong nulls_ratio;
 
  /*
    Average number of bytes occupied by the representation of a
    value of the column in memory buffers such as join buffer
    multiplied by the scale factor Scale_factor_avg_length.
    CHAR values are stripped of trailing spaces.
    Flexible values are stripped of their length prefixes.
  */
  ulonglong avg_length;

/*
    The ratio N/D multiplied by the scale factor Scale_factor_avg_frequency,
    where
       N is the number of rows with not null value in the column,
       D the number of distinct values among them
  */
  ulonglong avg_frequency;

public:

Histogram histogram;

uint32 no_values_provided_bitmap()
  {
    return
     ((1 << (COLUMN_STAT_HISTOGRAM-COLUMN_STAT_COLUMN_NAME))-1) <<
      (COLUMN_STAT_COLUMN_NAME+1);
  }
 
  void set_all_nulls()
  {
    column_stat_nulls= no_values_provided_bitmap();
  }

void set_not_null(uint stat_field_no)
  {
    column_stat_nulls&= ~(1 << stat_field_no);
  }

bool is_null(uint stat_field_no)
  {
    return MY_TEST(column_stat_nulls & (1 << stat_field_no));
  }

double get_nulls_ratio()
  {
    return (double) nulls_ratio /  Scale_factor_nulls_ratio;
  }

double get_avg_length()
  {
    return (double) avg_length / Scale_factor_avg_length;
  }

double get_avg_frequency()
  {
    return (double) avg_frequency / Scale_factor_avg_frequency;
  }

void set_nulls_ratio (double val)
  {
    nulls_ratio= (ulong) (val * Scale_factor_nulls_ratio);
  }

void set_avg_length (double val)
  {
    avg_length= (ulonglong) (val * Scale_factor_avg_length);
  }

void set_avg_frequency (double val)
  {
    avg_frequency= (ulonglong) (val * Scale_factor_avg_frequency);
  }

bool min_max_values_are_provided()
  {
    return !is_null(COLUMN_STAT_MIN_VALUE) && 
      !is_null(COLUMN_STAT_MAX_VALUE);
  }
  /*
    This function checks whether the values for the fields of the statistical
    tables that were NULL by DEFAULT for a column have changed or not.

@retval
    TRUE: Statistics are not present for a column
    FALSE: Statisitics are present for a column
  */
  bool no_stat_values_provided()
  {
    return (column_stat_nulls == no_values_provided_bitmap());
  }
};

/* Statistical data on an index prefixes */

class Index_statistics
{

private:
  static const uint Scale_factor_avg_frequency= 100000;
  /*
    The k-th element of this array contains the ratio N/D
    multiplied by the scale factor Scale_factor_avg_frequency, 
    where N is the number of index entries without nulls 
    in the first k components, and D is the number of distinct
    k-component prefixes among them 
  */
  ulonglong *avg_frequency;

public:

void init_avg_frequency(ulonglong *ptr) { avg_frequency= ptr; }

bool avg_frequency_is_inited() { return avg_frequency != NULL; }

double get_avg_frequency(uint i) const
  {
    return (double) avg_frequency[i] / Scale_factor_avg_frequency;
  }

void set_avg_frequency(uint i, double val)
  {
    avg_frequency[i]= (ulonglong) (val * Scale_factor_avg_frequency);
  }

};

#endif /* SQL_STATISTICS_H */

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