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Merge 10.0-base -> 10.0

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This commit is contained in:
Igor Babaev
2013-04-22 20:55:22 -07:00
parent 16c3fbab03 bb5b0a9f5b
commit cd0e834d12
25 changed files with 1073 additions and 11 deletions
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69
sql/opt_range.cc
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@ -3530,7 +3530,74 @@ bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item *cond)
}
}
}
}
}
/* Calculate selectivity of probably highly selective predicates */
ulong check_rows=
min(thd->variables.optimizer_selectivity_sampling_limit,
(ulong) (table_records * SELECTIVITY_SAMPLING_SHARE));
if (cond && check_rows > SELECTIVITY_SAMPLING_THRESHOLD &&
thd->variables.optimizer_use_condition_selectivity > 4)
{
find_selective_predicates_list_processor_data *dt=
(find_selective_predicates_list_processor_data *)
alloc_root(thd->mem_root,
sizeof(find_selective_predicates_list_processor_data));
if (!dt)
DBUG_RETURN(TRUE);
dt->list.empty();
dt->table= table;
if (cond->walk(&Item::find_selective_predicates_list_processor, 0,
(uchar*) dt))
DBUG_RETURN(TRUE);
if (dt->list.elements > 0)
{
check_rows= check_selectivity(thd, check_rows, table, &dt->list);
if (check_rows > SELECTIVITY_SAMPLING_THRESHOLD)
{
COND_STATISTIC *stat;
List_iterator_fast<COND_STATISTIC> it(dt->list);
double examined_rows= check_rows;
while ((stat= it++))
{
if (!stat->positive)
{
DBUG_PRINT("info", ("To avoid 0 assigned 1 to the counter"));
stat->positive= 1; // avoid 0
}
DBUG_PRINT("info", ("The predicate selectivity : %g",
(double)stat->positive / examined_rows));
double selectivity= ((double)stat->positive) / examined_rows;
table->cond_selectivity*= selectivity;
/*
If a field is involved then we register its selectivity in case
there in an equality with the field.
For example in case
t1.a LIKE "%bla%" and t1.a = t2.b
the selectivity we have found could be used also for t2.
*/
if (stat->field_arg)
{
stat->field_arg->cond_selectivity*= selectivity;
if (stat->field_arg->next_equal_field)
{
for (Field *next_field= stat->field_arg->next_equal_field;
next_field != stat->field_arg;
next_field= next_field->next_equal_field)
{
next_field->cond_selectivity*= selectivity;
next_field->table->cond_selectivity*= selectivity;
}
}
}
}
}
/* This list and its elements put to mem_root so should not be freed */
table->cond_selectivity_sampling_explain= &dt->list;
}
}
DBUG_RETURN(FALSE);
}