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?? ..
?? aligned.h(1.11 KB)
?? aria_backup.h(1.51 KB)
?? assume_aligned.h(2.29 KB)
?? atomic
?? authors.h(9.9 KB)
?? backup.h(1.66 KB)
?? bounded_queue.h(5.95 KB)
?? char_buffer.h(3.09 KB)
?? charset_collations.h(6.41 KB)
?? client_settings.h(1.87 KB)
?? compat56.h(2.23 KB)
?? config.h(14.21 KB)
?? contributors.h(4.76 KB)
?? create_options.h(4.09 KB)
?? create_tmp_table.h(2.74 KB)
?? cset_narrowing.h(3.88 KB)
?? custom_conf.h(1.06 KB)
?? data
?? datadict.h(1.66 KB)
?? ddl_log.h(12.51 KB)
?? debug.h(1.26 KB)
?? debug_sync.h(2 KB)
?? deprecation.h(2.74 KB)
?? derived_handler.h(2.32 KB)
?? derror.h(980 B)
?? des_key_file.h(1.21 KB)
?? discover.h(1.53 KB)
?? dur_prop.h(1.06 KB)
?? embedded_priv.h(1.69 KB)
?? event_data_objects.h(4.09 KB)
?? event_db_repository.h(3.56 KB)
?? event_parse_data.h(2.83 KB)
?? event_queue.h(3.36 KB)
?? event_scheduler.h(3.21 KB)
?? events.h(4.6 KB)
?? field.h(217.81 KB)
?? field_comp.h(1.15 KB)
?? filesort.h(7.13 KB)
?? filesort_utils.h(10.53 KB)
?? ft_global.h(3.04 KB)
?? gcalc_slicescan.h(16.87 KB)
?? gcalc_tools.h(11.62 KB)
?? grant.h(2.69 KB)
?? group_by_handler.h(3.45 KB)
?? gstream.h(2.38 KB)
?? gtid_index.h(19.54 KB)
?? ha_handler_stats.h(2.28 KB)
?? ha_partition.h(63.36 KB)
?? ha_sequence.h(6.1 KB)
?? handle_connections_win.h(884 B)
?? handler.h(206.19 KB)
?? hash.h(4.35 KB)
?? hash_filo.h(5.55 KB)
?? heap.h(9.26 KB)
?? hostname.h(5.29 KB)
?? ilist.h(6.98 KB)
?? init.h(852 B)
?? innodb_priv.h(1.29 KB)
?? item.h(276.43 KB)
?? item_cmpfunc.h(132.01 KB)
?? item_create.h(11.24 KB)
?? item_func.h(134.64 KB)
?? item_geofunc.h(38.16 KB)
?? item_jsonfunc.h(27.86 KB)
?? item_row.h(5.1 KB)
?? item_strfunc.h(75.33 KB)
?? item_subselect.h(57.63 KB)
?? item_sum.h(70.69 KB)
?? item_timefunc.h(63.85 KB)
?? item_vers.h(4.26 KB)
?? item_windowfunc.h(33.56 KB)
?? item_xmlfunc.h(4.52 KB)
?? json_schema.h(25.1 KB)
?? json_schema_helper.h(1.13 KB)
?? json_table.h(9.44 KB)
?? key.h(2.08 KB)
?? keycaches.h(1.94 KB)
?? lex.h(29.54 KB)
?? lex_charset.h(25.92 KB)
?? lex_hash.h(141.94 KB)
?? lex_ident.h(5.15 KB)
?? lex_string.h(4.77 KB)
?? lex_symbol.h(1.29 KB)
?? lex_token.h(42.01 KB)
?? lf.h(6.31 KB)
?? lock.h(2.2 KB)
?? log.h(51.28 KB)
?? log_cache.h(7.57 KB)
?? log_event.h(172.56 KB)
?? log_event_data_type.h(1.85 KB)
?? log_slow.h(2.38 KB)
?? maria.h(5.73 KB)
?? mariadb.h(1.25 KB)
?? mdl.h(37.65 KB)
?? mem_root_array.h(6.94 KB)
?? message.h(1.17 KB)
?? multi_range_read.h(22.65 KB)
?? my_apc.h(4.64 KB)
?? my_atomic.h(7.11 KB)
?? my_atomic_wrapper.h(2.98 KB)
?? my_base.h(27.28 KB)
?? my_bit.h(6.05 KB)
?? my_bitmap.h(5.37 KB)
?? my_check_opt.h(2.56 KB)
?? my_compare.h(10.87 KB)
?? my_counter.h(1.68 KB)
?? my_cpu.h(4.74 KB)
?? my_crypt.h(904 B)
?? my_decimal.h(14.15 KB)
?? my_default.h(1.84 KB)
?? my_handler_errors.h(4.77 KB)
?? my_json_writer.h(18.14 KB)
?? my_libwrap.h(1.16 KB)
?? my_md5.h(1.45 KB)
?? my_minidump.h(848 B)
?? my_nosys.h(1.4 KB)
?? my_rdtsc.h(9.88 KB)
?? my_rnd.h(1014 B)
?? my_service_manager.h(2.07 KB)
?? my_stack_alloc.h(6.34 KB)
?? my_stacktrace.h(3.14 KB)
?? my_time.h(10.17 KB)
?? my_tracker.h(1.37 KB)
?? my_tree.h(3.9 KB)
?? my_uctype.h(67.9 KB)
?? my_user.h(1.1 KB)
?? my_virtual_mem.h(1.1 KB)
?? myisam.h(17.18 KB)
?? myisamchk.h(4.62 KB)
?? myisammrg.h(4.78 KB)
?? myisampack.h(14.58 KB)
?? mysqld.h(41.11 KB)
?? mysqld_default_groups.h(204 B)
?? mysqld_suffix.h(1.17 KB)
?? mysys_err.h(2.99 KB)
?? opt_histogram_json.h(4.71 KB)
?? opt_range.h(64.78 KB)
?? opt_rewrite_date_cmp.h(3.84 KB)
?? opt_subselect.h(14.78 KB)
?? opt_trace.h(8.29 KB)
?? opt_trace_context.h(3.21 KB)
?? optimizer_costs.h(5.89 KB)
?? optimizer_defaults.h(7.37 KB)
?? parse_file.h(4.28 KB)
?? partition_element.h(5.3 KB)
?? partition_info.h(19.4 KB)
?? password.h(1.14 KB)
?? pfs_file_provider.h(3.08 KB)
?? pfs_idle_provider.h(1.35 KB)
?? pfs_memory_provider.h(1.59 KB)
?? pfs_metadata_provider.h(1.85 KB)
?? pfs_socket_provider.h(2.21 KB)
?? pfs_stage_provider.h(1.52 KB)
?? pfs_statement_provider.h(4.25 KB)
?? pfs_table_provider.h(2.56 KB)
?? pfs_thread_provider.h(5.43 KB)
?? pfs_transaction_provider.h(2.78 KB)
?? privilege.h(28.44 KB)
?? probes_mysql.h(973 B)
?? probes_mysql_dtrace.h(32.23 KB)
?? probes_mysql_nodtrace.h(5.94 KB)
?? procedure.h(6.63 KB)
?? protocol.h(12.27 KB)
?? providers
?? proxy_protocol.h(548 B)
?? queues.h(3.4 KB)
?? records.h(3.07 KB)
?? repl_failsafe.h(1.55 KB)
?? replication.h(15.2 KB)
?? rijndael.h(1.67 KB)
?? rowid_filter.h(16.03 KB)
?? rpl_constants.h(3.28 KB)
?? rpl_filter.h(4.66 KB)
?? rpl_gtid.h(29.95 KB)
?? rpl_injector.h(9.4 KB)
?? rpl_mi.h(16.29 KB)
?? rpl_parallel.h(17.8 KB)
?? rpl_record.h(1.49 KB)
?? rpl_reporting.h(3.63 KB)
?? rpl_rli.h(35.02 KB)
?? rpl_tblmap.h(3.1 KB)
?? rpl_utility.h(10.93 KB)
?? scheduler.h(3.12 KB)
?? scope.h(4.29 KB)
?? select_handler.h(3.34 KB)
?? semisync.h(2.23 KB)
?? semisync_master.h(25.16 KB)
?? semisync_master_ack_receiver.h(8.5 KB)
?? semisync_slave.h(3.65 KB)
?? service_versions.h(2.23 KB)
?? session_tracker.h(13.75 KB)
?? set_var.h(16.39 KB)
?? simple_tokenizer.h(1.97 KB)
?? slave.h(11.99 KB)
?? socketpair.h(842 B)
?? source_revision.h(67 B)
?? sp.h(23.11 KB)
?? sp_cache.h(1.99 KB)
?? sp_head.h(38.61 KB)
?? sp_instr.h(40.41 KB)
?? sp_pcontext.h(24.71 KB)
?? sp_rcontext.h(14.08 KB)
?? span.h(3.84 KB)
?? spatial.h(21.78 KB)
?? sql_acl.h(13.75 KB)
?? sql_admin.h(2.85 KB)
?? sql_alloc.h(1.69 KB)
?? sql_alter.h(15.08 KB)
?? sql_analyse.h(10.86 KB)
?? sql_analyze_stmt.h(12.4 KB)
?? sql_array.h(6.97 KB)
?? sql_audit.h(13.83 KB)
?? sql_base.h(25.87 KB)
?? sql_basic_types.h(9.3 KB)
?? sql_binlog.h(895 B)
?? sql_bitmap.h(7.88 KB)
?? sql_bootstrap.h(1.77 KB)
?? sql_cache.h(21.34 KB)
?? sql_callback.h(1.51 KB)
?? sql_class.h(270.56 KB)
?? sql_cmd.h(15.11 KB)
?? sql_connect.h(3.96 KB)
?? sql_const.h(10.07 KB)
?? sql_crypt.h(1.4 KB)
?? sql_cte.h(16.15 KB)
?? sql_cursor.h(4.14 KB)
?? sql_db.h(2.28 KB)
?? sql_debug.h(5.51 KB)
?? sql_delete.h(3.52 KB)
?? sql_derived.h(1.26 KB)
?? sql_digest.h(3.73 KB)
?? sql_digest_stream.h(1.53 KB)
?? sql_do.h(954 B)
?? sql_error.h(39.39 KB)
?? sql_explain.h(30.39 KB)
?? sql_expression_cache.h(4.26 KB)
?? sql_get_diagnostics.h(7.7 KB)
?? sql_handler.h(2.84 KB)
?? sql_help.h(995 B)
?? sql_hset.h(3.32 KB)
?? sql_i_s.h(8.29 KB)
?? sql_insert.h(5.05 KB)
?? sql_join_cache.h(47.52 KB)
?? sql_lex.h(174.22 KB)
?? sql_lifo_buffer.h(9.45 KB)
?? sql_limit.h(3.11 KB)
?? sql_list.h(21.87 KB)
?? sql_load.h(1.25 KB)
?? sql_locale.h(3.16 KB)
?? sql_manager.h(960 B)
?? sql_mode.h(6.58 KB)
?? sql_parse.h(8.31 KB)
?? sql_partition.h(12.38 KB)
?? sql_partition_admin.h(5.8 KB)
?? sql_plist.h(7.53 KB)
?? sql_plugin.h(7.4 KB)
?? sql_plugin_compat.h(2.18 KB)
?? sql_prepare.h(11.4 KB)
?? sql_priv.h(15.08 KB)
?? sql_profile.h(7.63 KB)
?? sql_reload.h(1.01 KB)
?? sql_rename.h(982 B)
?? sql_repl.h(2.99 KB)
?? sql_schema.h(3.23 KB)
?? sql_select.h(91 KB)
?? sql_sequence.h(5.06 KB)
?? sql_servers.h(1.74 KB)
?? sql_show.h(9.73 KB)
?? sql_signal.h(3.28 KB)
?? sql_sort.h(21.96 KB)
?? sql_statistics.h(16.41 KB)
?? sql_string.h(37.92 KB)
?? sql_table.h(9.52 KB)
?? sql_test.h(1.55 KB)
?? sql_time.h(7.24 KB)
?? sql_trigger.h(11.88 KB)
?? sql_truncate.h(2.03 KB)
?? sql_tvc.h(2.36 KB)
?? sql_type.h(291.25 KB)
?? sql_type_fixedbin.h(63.94 KB)
?? sql_type_fixedbin_storage.h(5.34 KB)
?? sql_type_geom.h(18.59 KB)
?? sql_type_int.h(9.77 KB)
?? sql_type_json.h(6.01 KB)
?? sql_type_real.h(1.23 KB)
?? sql_type_string.h(1.59 KB)
?? sql_type_timeofday.h(2.26 KB)
?? sql_udf.h(4.74 KB)
?? sql_union.h(1.04 KB)
?? sql_update.h(3.55 KB)
?? sql_used.h(1.02 KB)
?? sql_view.h(2.41 KB)
?? sql_window.h(6.65 KB)
?? ssl_compat.h(3.3 KB)
?? strfunc.h(2.22 KB)
?? structs.h(30.55 KB)
?? sys_vars_shared.h(2.67 KB)
?? t_ctype.h(5.51 KB)
?? table.h(118.11 KB)
?? table_cache.h(4.13 KB)
?? thr_lock.h(7.06 KB)
?? thr_malloc.h(1.17 KB)
?? thr_timer.h(1.53 KB)
?? thread_cache.h(5.77 KB)
?? threadpool.h(4.7 KB)
?? threadpool_generic.h(3.88 KB)
?? threadpool_winsockets.h(2.24 KB)
?? transaction.h(1.43 KB)
?? tzfile.h(4.9 KB)
?? tztime.h(3.65 KB)
?? uniques.h(4.13 KB)
?? unireg.h(7.76 KB)
?? vers_string.h(2.39 KB)
?? violite.h(9.85 KB)
?? waiting_threads.h(4.43 KB)
?? welcome_copyright_notice.h(1.42 KB)
?? winservice.h(5.88 KB)
?? wqueue.h(1.53 KB)
?? wsrep.h(3.23 KB)
?? wsrep_allowlist_service.h(1.01 KB)
?? wsrep_applier.h(2.64 KB)
?? wsrep_binlog.h(3.36 KB)
?? wsrep_client_service.h(2.5 KB)
?? wsrep_client_state.h(1.53 KB)
?? wsrep_condition_variable.h(1.45 KB)
?? wsrep_event_service.h(1.32 KB)
?? wsrep_high_priority_service.h(4.8 KB)
?? wsrep_mutex.h(1.21 KB)
?? wsrep_mysqld.h(20.93 KB)
?? wsrep_mysqld_c.h(1.2 KB)
?? wsrep_on.h(1.68 KB)
?? wsrep_plugin.h(1.35 KB)
?? wsrep_priv.h(1.6 KB)
?? wsrep_schema.h(5.48 KB)
?? wsrep_server_service.h(3.55 KB)
?? wsrep_server_state.h(3.06 KB)
?? wsrep_sst.h(3.86 KB)
?? wsrep_status.h(1.93 KB)
?? wsrep_storage_service.h(1.77 KB)
?? wsrep_thd.h(10.9 KB)
?? wsrep_trans_observer.h(17.75 KB)
?? wsrep_types.h(1.08 KB)
?? wsrep_utils.h(9.58 KB)
?? wsrep_var.h(4.25 KB)
?? wsrep_xid.h(1.51 KB)
?? xa.h(1.86 KB)

Editing: sql_statistics.h

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

#include <vector>
#include <string>

/*
  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,
  JSON_HB,
  INVALID_HISTOGRAM
} 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);
void free_statistics_for_table(TABLE *table);
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_builder;

/*
  Common base for all histograms
*/
class Histogram_base :public Sql_alloc
{
public:
  Histogram_base() {}
  virtual ~Histogram_base()= default;

virtual bool parse(MEM_ROOT *mem_root,
                     const char *db_name, const char *table_name,
                     Field *field, const char *hist_data,
                     size_t hist_data_len)= 0;
  virtual void serialize(Field *to_field)= 0;

virtual Histogram_type get_type()=0;

virtual uint get_width()=0;

/*
    The creation-time workflow is:
     * create a histogram
     * init_for_collection()
     * create_builder()
     * feed the data to the builder
     * serialize();
  */
  virtual void init_for_collection(MEM_ROOT *mem_root, Histogram_type htype_arg,
                                   ulonglong size)=0;
  virtual Histogram_builder *create_builder(Field *col, uint col_len,
                                            ha_rows rows)=0;

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

virtual double point_selectivity(Field *field, key_range *endpoint,
                                   double avg_sel)=0;
  virtual double range_selectivity(Field *field, key_range *min_endp,
                                   key_range *max_endp, double avg_sel)=0;
  /*
    Legacy: return the size of the histogram on disk.

This will be stored in mysql.column_stats.hist_size column.
    The value is not really needed as one can look at
    LENGTH(mysql.column_stats.histogram) directly.
  */
  virtual uint get_size()=0;
};

/*
  A Height-balanced histogram that stores numeric fractions
*/

class Histogram_binary final : public Histogram_base
{
private:
  Histogram_type type;
  size_t 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);
    default:
      DBUG_ASSERT(0);
    }
    return 1;
  }

public:
  Histogram_binary(Histogram_type type_arg) : type(type_arg)
  {}

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

/* Find the bucket which value 'pos' falls into. */
  uint find_bucket(double pos, bool first)
  {
    size_t val= (size_t) (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() override {return (uint)size;}

Histogram_type get_type() override { return type; }

bool parse(MEM_ROOT *mem_root, const char*, const char*, Field*,
             const char *hist_data, size_t hist_data_len) override;
  void serialize(Field *to_field) override;
  void init_for_collection(MEM_ROOT *mem_root, Histogram_type htype_arg,
                           ulonglong size) override;
  Histogram_builder *create_builder(Field *col, uint col_len,
                                    ha_rows rows) override;

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;
    default:
      DBUG_ASSERT(0);
      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;
    default:
      DBUG_ASSERT(0);
      return;
    }
  }

double range_selectivity(Field *field, key_range *min_endp,
                           key_range *max_endp, double avg_sel) override;

/*
    Estimate selectivity of "col=const" using a histogram
  */
  double point_selectivity(Field *field, key_range *endpoint,
                           double avg_sel) override;
};

/*
  This is used to collect the basic statistics from a Unique object:
   - count of values
   - count of distinct values
   - count of distinct values that have occurred only once
*/

class Basic_stats_collector
{
  ulonglong count;         /* number of values retrieved                   */
  ulonglong count_distinct;    /* number of distinct values retrieved      */
  /* number of distinct values that occurred only once  */
  ulonglong count_distinct_single_occurence;

public:
  Basic_stats_collector()
  {
    count= 0;
    count_distinct= 0;
    count_distinct_single_occurence= 0;
  }

ulonglong get_count_distinct() const { return count_distinct; }
  ulonglong get_count_single_occurence() const
  {
    return count_distinct_single_occurence;
  }
  ulonglong get_count() const { return count; }

void next(void *elem, element_count elem_cnt)
  {
    count_distinct++;
    if (elem_cnt == 1)
      count_distinct_single_occurence++;
    count+= elem_cnt;
  }
};

/*
  Histogram_builder is a helper class that is used to build histograms
  for columns.

Do not create directly, call Histogram->get_builder(...);
*/

class Histogram_builder: public Sql_alloc
{
protected:
  Field *column;           /* table field for which the histogram is built */
  uint col_length;         /* size of this field                           */
  ha_rows records;         /* number of records the histogram is built for */

Histogram_builder(Field *col, uint col_len, ha_rows rows) :
    column(col), col_length(col_len), records(rows)
  {}

public:
  // A histogram builder will also collect the counters
  Basic_stats_collector counters;

virtual int next(void *elem, element_count elem_cnt)=0;
  virtual void finalize()=0;
  virtual ~Histogram_builder(){}
};

class Column_statistics;
class Index_statistics;

/* Statistical data on a table */

class Table_statistics
{
public:
  my_bool cardinality_is_null;      /* TRUE if the cardinality is unknown */
  uint  columns;                    /* Number of columns in table */
  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 :public Sql_alloc
{

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:
  ~Column_statistics()
  {
    delete histogram;
  }
  /* 
    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_base *histogram;
  bool histogram_exists;

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);
  }

void set_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;
  bool stats_were_read;

public:
  void init_avg_frequency(ulonglong *ptr)
  {
    avg_frequency= ptr;
    stats_were_read= false;
  }

void mark_stats_as_read() { stats_were_read= true; }

bool has_stats(THD *thd) const
  {
    if (TEST_NEW_MODE_FLAG(thd, NEW_MODE_FIX_INDEX_STATS_FOR_ALL_NULLS))
      return stats_were_read;
    else
      return get_avg_frequency(0) > 0.5;
  }

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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