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The pilot implementation of mwl#250: Use the statistics from persistent

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statistical tables instead of the statistics provided by engine.
This commit is contained in:
Igor Babaev
2012-04-11 17:14:06 -07:00
parent ff3d16fba8
commit 1c0a89afcc
15 changed files with 706 additions and 52 deletions
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55
sql/sql_statistics.cc
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@ -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);
}
}