diff options
Diffstat (limited to 'sql/sql_statistics.cc')
| -rw-r--r-- | sql/sql_statistics.cc | 55 |
1 files changed, 54 insertions, 1 deletions
diff --git a/sql/sql_statistics.cc b/sql/sql_statistics.cc index 89f3c23d5af..27aa77ae1a3 100644 --- a/sql/sql_statistics.cc +++ b/sql/sql_statistics.cc @@ -1531,7 +1531,7 @@ int update_statistics_for_table(THD *thd, TABLE *table) now. */ -int read_statistics_for_table(THD *thd, struct TABLE *table) +int read_statistics_for_table(THD *thd, TABLE *table) { uint i; TABLE *stat_table; @@ -1579,6 +1579,29 @@ int read_statistics_for_table(THD *thd, struct TABLE *table) index_stat.set_key_fields(key_info, i+1); index_stat.get_stat_values(); } + + key_part_map ext_key_part_map= key_info->ext_key_part_map; + if (key_info->key_parts != key_info->ext_key_parts) + { + KEY *pk_key_info= table->key_info + table->s->primary_key; + uint k= key_info->key_parts; + double k_avg_frequency= key_info->read_stat.avg_frequency[k-1]; + uint pk_parts= pk_key_info->key_parts; + ha_rows n_rows= table->read_stat.cardinality; + for (uint j= 0; j < pk_parts; j++) + { + double avg_frequency; + if (!(ext_key_part_map & 1 << j)) + continue; + avg_frequency= pk_key_info->read_stat.avg_frequency[j]; + if (avg_frequency == 0 || + table->read_stat.cardinality_is_null) + avg_frequency= 1; + else if (avg_frequency > 1) + avg_frequency= max(k_avg_frequency * avg_frequency / n_rows, 1); + key_info->read_stat.avg_frequency[k++]= avg_frequency; + } + } } close_system_tables(thd, &open_tables_backup); @@ -1586,3 +1609,33 @@ int read_statistics_for_table(THD *thd, struct TABLE *table) DBUG_RETURN(0); } + +/** + @brief + Set statistics for a table that will be used by the optimizer + + @param + thd The thread handle + @param + table The table to set statistics for + + @details + Depending on the value of thd->variables.optimizer_use_stat_tables + the function performs the settings for the table that will control + from where the statistical data used by the optimizer will be taken. +*/ + +void set_statistics_for_table(THD *thd, TABLE *table) +{ + uint use_stat_table_mode= thd->variables.optimizer_use_stat_tables; + table->used_stat_records= + (use_stat_table_mode <= 1 || table->read_stat.cardinality_is_null) ? + table->file->stats.records : table->read_stat.cardinality; + KEY *key_info, *key_info_end; + for (key_info= table->key_info, key_info_end= key_info+table->s->keys; + key_info < key_info_end; key_info++) + { + key_info->is_statistics_from_stat_tables= + (use_stat_table_mode > 1 && key_info->read_stat.avg_frequency[0] > 0.5); + } +} |