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353 lines
8.6 KiB
C++
353 lines
8.6 KiB
C++
/* Copyright 2006-2008 MySQL AB, 2008 Sun Microsystems, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#ifndef SQL_STATISTICS_H
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#define SQL_STATISTICS_H
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typedef
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enum enum_use_stat_tables_mode
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{
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NEVER,
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COMPLEMENTARY,
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PEFERABLY,
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} Use_stat_tables_mode;
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enum enum_stat_tables
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{
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TABLE_STAT,
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COLUMN_STAT,
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INDEX_STAT,
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};
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/*
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These enumeration types comprise the dictionary of three
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statistical tables table_stat, column_stat and index_stat
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as they defined in ../scripts/mysql_system_tables.sql.
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It would be nice if the declarations of these types were
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generated automatically by the table definitions.
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*/
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enum enum_table_stat_col
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{
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TABLE_STAT_DB_NAME,
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TABLE_STAT_TABLE_NAME,
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TABLE_STAT_CARDINALITY
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};
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enum enum_column_stat_col
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{
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COLUMN_STAT_DB_NAME,
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COLUMN_STAT_TABLE_NAME,
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COLUMN_STAT_COLUMN_NAME,
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COLUMN_STAT_MIN_VALUE,
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COLUMN_STAT_MAX_VALUE,
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COLUMN_STAT_NULLS_RATIO,
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COLUMN_STAT_AVG_LENGTH,
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COLUMN_STAT_AVG_FREQUENCY,
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COLUMN_STAT_HIST_SIZE,
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COLUMN_STAT_HISTOGRAM
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};
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enum enum_index_stat_col
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{
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INDEX_STAT_DB_NAME,
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INDEX_STAT_TABLE_NAME,
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INDEX_STAT_INDEX_NAME,
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INDEX_STAT_PREFIX_ARITY,
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INDEX_STAT_AVG_FREQUENCY
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};
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inline
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Use_stat_tables_mode get_use_stat_tables_mode(THD *thd)
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{
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return (Use_stat_tables_mode) (thd->variables.use_stat_tables);
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}
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int read_statistics_for_tables_if_needed(THD *thd, TABLE_LIST *tables);
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int collect_statistics_for_table(THD *thd, TABLE *table);
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int alloc_statistics_for_table_share(THD* thd, TABLE_SHARE *share,
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bool is_safe);
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int alloc_statistics_for_table(THD *thd, TABLE *table);
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int update_statistics_for_table(THD *thd, TABLE *table);
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int delete_statistics_for_table(THD *thd, LEX_STRING *db, LEX_STRING *tab);
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int delete_statistics_for_column(THD *thd, TABLE *tab, Field *col);
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int delete_statistics_for_index(THD *thd, TABLE *tab, KEY *key_info,
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bool ext_prefixes_only);
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int rename_table_in_stat_tables(THD *thd, LEX_STRING *db, LEX_STRING *tab,
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LEX_STRING *new_db, LEX_STRING *new_tab);
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int rename_column_in_stat_tables(THD *thd, TABLE *tab, Field *col,
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const char *new_name);
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void set_statistics_for_table(THD *thd, TABLE *table);
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double get_column_avg_frequency(Field * field);
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double get_column_range_cardinality(Field *field,
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key_range *min_endp,
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key_range *max_endp);
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#define HIST_FACTOR 255
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#define INV_HIST_FACTOR ((double) 1.0 / HIST_FACTOR)
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class Histogram
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{
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private:
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public:
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private:
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uint8 size;
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uint8 *values;
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uint find_bucket(double pos, bool first)
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{
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uint8 val= (uint8) (pos * HIST_FACTOR);
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int lp= 0;
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int rp= size - 1;
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int i= 0;
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for (int d= size / 2 ; d; d= (rp - lp) / 2)
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{
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i= lp + d;
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if (val == values[i])
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break;
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if (val < values[i])
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rp= i;
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else if (val > values[i + 1])
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lp= i + 1;
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else
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break;
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}
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if (val == values[i])
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{
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if (first)
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{
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while(i && val == values[i - 1])
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i--;
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}
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else
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{
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while(i + 1 < size && val == values[i + 1])
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i++;
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}
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}
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return i;
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}
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public:
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uint get_size() { return (uint) size; }
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uchar *get_values() { return (uchar *) values; }
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void set_size (ulonglong sz) { size= (uint8) sz; }
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void set_values (uchar *vals) { values= (uint8 *) vals; }
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void set_value(uint i, double val)
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{
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values[i]= (uint8) (val * HIST_FACTOR);
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}
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void set_prev_value(uint i) { values[i]= values[i-1]; }
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double range_selectivity(double min_pos, double max_pos)
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{
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double sel;
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double bucket_sel= 1.0/(size + 1);
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uint min= find_bucket(min_pos, TRUE);
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uint max= find_bucket(max_pos, FALSE);
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sel= bucket_sel * (max - min + 1);
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return sel;
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}
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double point_selectivity(double pos, double avg_sel)
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{
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double sel;
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double bucket_sel= 1.0/(size + 1);
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uint min= find_bucket(pos, TRUE);
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uint max= min;
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while (max + 1 < size && values[max + 1] == values[max])
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max++;
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double width= ((max + 1 == size ? 1.0 : values[max]) -
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(min == 0 ? 0.0 : values[min-1])) *
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INV_HIST_FACTOR;
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sel= avg_sel * (bucket_sel * (max + 1 - min)) / width;
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return sel;
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}
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};
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class Columns_statistics;
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class Index_statistics;
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/* Statistical data on a table */
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class Table_statistics
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{
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public:
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my_bool cardinality_is_null; /* TRUE if the cardinality is unknown */
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ha_rows cardinality; /* Number of rows in the table */
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uchar *min_max_record_buffers; /* Record buffers for min/max values */
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Column_statistics *column_stats; /* Array of statistical data for columns */
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Index_statistics *index_stats; /* Array of statistical data for indexes */
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ulong *idx_avg_frequency; /* Array of records per key for index prefixes */
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ulong total_hist_size;
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uchar *histograms; /* Sequence of histograms */
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};
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/* Statistical data on a column */
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class Column_statistics
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{
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private:
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static const uint Scale_factor_nulls_ratio= 100000;
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static const uint Scale_factor_avg_length= 100000;
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static const uint Scale_factor_avg_frequency= 100000;
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public:
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/*
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Bitmap indicating what statistical characteristics
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are available for the column
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*/
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uint32 column_stat_nulls;
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/* Minimum value for the column */
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Field *min_value;
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/* Maximum value for the column */
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Field *max_value;
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private:
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/*
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The ratio Z/N multiplied by the scale factor Scale_factor_nulls_ratio,
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where
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N is the total number of rows,
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Z is the number of nulls in the column
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*/
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ulong nulls_ratio;
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/*
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Average number of bytes occupied by the representation of a
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value of the column in memory buffers such as join buffer
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multiplied by the scale factor Scale_factor_avg_length.
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CHAR values are stripped of trailing spaces.
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Flexible values are stripped of their length prefixes.
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*/
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ulong avg_length;
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/*
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The ratio N/D multiplied by the scale factor Scale_factor_avg_frequency,
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where
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N is the number of rows with not null value in the column,
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D the number of distinct values among them
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*/
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ulong avg_frequency;
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public:
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Histogram histogram;
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void set_all_nulls()
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{
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column_stat_nulls=
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((1 << (COLUMN_STAT_HISTOGRAM-COLUMN_STAT_COLUMN_NAME))-1) <<
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(COLUMN_STAT_COLUMN_NAME+1);
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}
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void set_not_null(uint stat_field_no)
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{
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column_stat_nulls&= ~(1 << stat_field_no);
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}
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bool is_null(uint stat_field_no)
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{
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return test(column_stat_nulls & (1 << stat_field_no));
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}
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double get_nulls_ratio()
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{
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return (double) nulls_ratio / Scale_factor_nulls_ratio;
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}
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double get_avg_length()
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{
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return (double) avg_length / Scale_factor_avg_length;
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}
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double get_avg_frequency()
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{
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return (double) avg_frequency / Scale_factor_avg_frequency;
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}
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void set_nulls_ratio (double val)
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{
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nulls_ratio= (ulong) (val * Scale_factor_nulls_ratio);
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}
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void set_avg_length (double val)
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{
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avg_length= (ulong) (val * Scale_factor_avg_length);
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}
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void set_avg_frequency (double val)
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{
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avg_frequency= (ulong) (val * Scale_factor_avg_frequency);
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}
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};
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/* Statistical data on an index prefixes */
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class Index_statistics
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{
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private:
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static const uint Scale_factor_avg_frequency= 100000;
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/*
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The k-th element of this array contains the ratio N/D
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multiplied by the scale factor Scale_factor_avg_frequency,
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where N is the number of index entries without nulls
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in the first k components, and D is the number of distinct
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k-component prefixes among them
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*/
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ulong *avg_frequency;
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public:
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void init_avg_frequency(ulong *ptr) { avg_frequency= ptr; }
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bool avg_frequency_is_inited() { return avg_frequency != NULL; }
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double get_avg_frequency(uint i)
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{
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return (double) avg_frequency[i] / Scale_factor_avg_frequency;
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}
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void set_avg_frequency(uint i, double val)
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{
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avg_frequency[i]= (ulong) (val * Scale_factor_avg_frequency);
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}
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};
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#endif /* SQL_STATISTICS_H */
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