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Commit fdec8852 authored by Monty's avatar Monty
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MDEV-25830 optimizer_use_condition_selectivity=4 sometimes produces worse plan... 

MDEV-25830 optimizer_use_condition_selectivity=4 sometimes produces worse plan than optimizer_use_condition_selectivity=1

The issue was that calc_cond_selectivity_for_table prefered ranges with
many parts and when deciding on which selectivity to use.

Fixed by going through ranges according to the number of rows in the range.

This ensures that selectivity from ranges with few rows will be prefered
over ranges with many rows for indexes that uses the same columns.
parent c75bee94
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Showing with 207 additions and 24 deletions
mysql-test/main/group_min_max.result
View file @ fdec8852
......@@ -2078,19 +2078,19 @@ id select_type table type possible_keys key key_len ref rows Extra
explain extended select a1,a2,min(b),max(b) from t1
where (a1 = 'b' or a1 = 'd' or a1 = 'a' or a1 = 'c') and (a2 > 'a') and (c > 'a111') group by a1,a2;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 range idx_t1_0,idx_t1_1,idx_t1_2 idx_t1_1 130 NULL 77 99.22 Using where; Using index
1 SIMPLE t1 range idx_t1_0,idx_t1_1,idx_t1_2 idx_t1_1 130 NULL 77 85.04 Using where; Using index
Warnings:
Note 1003 select `test`.`t1`.`a1` AS `a1`,`test`.`t1`.`a2` AS `a2`,min(`test`.`t1`.`b`) AS `min(b)`,max(`test`.`t1`.`b`) AS `max(b)` from `test`.`t1` where (`test`.`t1`.`a1` = 'b' or `test`.`t1`.`a1` = 'd' or `test`.`t1`.`a1` = 'a' or `test`.`t1`.`a1` = 'c') and `test`.`t1`.`a2` > 'a' and `test`.`t1`.`c` > 'a111' group by `test`.`t1`.`a1`,`test`.`t1`.`a2`
explain extended select a1,a2,b,min(c),max(c) from t1
where (a1 = 'b' or a1 = 'd' or a1 = 'a' or a1 = 'c') and (a2 > 'a') and (d > 'xy2') group by a1,a2,b;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ALL idx_t1_0,idx_t1_1,idx_t1_2 NULL NULL NULL 128 45.12 Using where; Using temporary; Using filesort
1 SIMPLE t1 ALL idx_t1_0,idx_t1_1,idx_t1_2 NULL NULL NULL 128 38.67 Using where; Using temporary; Using filesort
Warnings:
Note 1003 select `test`.`t1`.`a1` AS `a1`,`test`.`t1`.`a2` AS `a2`,`test`.`t1`.`b` AS `b`,min(`test`.`t1`.`c`) AS `min(c)`,max(`test`.`t1`.`c`) AS `max(c)` from `test`.`t1` where (`test`.`t1`.`a1` = 'b' or `test`.`t1`.`a1` = 'd' or `test`.`t1`.`a1` = 'a' or `test`.`t1`.`a1` = 'c') and `test`.`t1`.`a2` > 'a' and `test`.`t1`.`d` > 'xy2' group by `test`.`t1`.`a1`,`test`.`t1`.`a2`,`test`.`t1`.`b`
explain extended select a1,a2,b,c from t1
where (a1 = 'b' or a1 = 'd' or a1 = 'a' or a1 = 'c') and (a2 > 'a') and (d > 'xy2') group by a1,a2,b,c;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 ALL idx_t1_0,idx_t1_1,idx_t1_2 NULL NULL NULL 128 45.12 Using where; Using temporary; Using filesort
1 SIMPLE t1 ALL idx_t1_0,idx_t1_1,idx_t1_2 NULL NULL NULL 128 38.67 Using where; Using temporary; Using filesort
Warnings:
Note 1003 select `test`.`t1`.`a1` AS `a1`,`test`.`t1`.`a2` AS `a2`,`test`.`t1`.`b` AS `b`,`test`.`t1`.`c` AS `c` from `test`.`t1` where (`test`.`t1`.`a1` = 'b' or `test`.`t1`.`a1` = 'd' or `test`.`t1`.`a1` = 'a' or `test`.`t1`.`a1` = 'c') and `test`.`t1`.`a2` > 'a' and `test`.`t1`.`d` > 'xy2' group by `test`.`t1`.`a1`,`test`.`t1`.`a2`,`test`.`t1`.`b`,`test`.`t1`.`c`
explain select a1,a2,b,max(c),min(c) from t2 where (a2 = 'a') and (b = 'b') or (b < 'b') group by a1;
......@@ -2098,7 +2098,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 index NULL idx_t2_1 163 NULL 164 Using where; Using index
explain extended select a1,a2,b from t1 where (a1 = 'b' or a1 = 'd' or a1 = 'a' or a1 = 'c') and (a2 > 'a') and (c > 'a111') group by a1,a2,b;
id select_type table type possible_keys key key_len ref rows filtered Extra
1 SIMPLE t1 range idx_t1_0,idx_t1_1,idx_t1_2 idx_t1_1 130 NULL 77 99.22 Using where; Using index
1 SIMPLE t1 range idx_t1_0,idx_t1_1,idx_t1_2 idx_t1_1 130 NULL 77 85.04 Using where; Using index
Warnings:
Note 1003 select `test`.`t1`.`a1` AS `a1`,`test`.`t1`.`a2` AS `a2`,`test`.`t1`.`b` AS `b` from `test`.`t1` where (`test`.`t1`.`a1` = 'b' or `test`.`t1`.`a1` = 'd' or `test`.`t1`.`a1` = 'a' or `test`.`t1`.`a1` = 'c') and `test`.`t1`.`a2` > 'a' and `test`.`t1`.`c` > 'a111' group by `test`.`t1`.`a1`,`test`.`t1`.`a2`,`test`.`t1`.`b`
explain select a1,a2,min(b),c from t2 where (a2 = 'a') and (c = 'a111') group by a1;
......
mysql-test/main/mdev-25830.result 0 → 100644
View file @ fdec8852
SET SESSION DEFAULT_STORAGE_ENGINE='InnoDB';
set @innodb_stats_persistent_save= @@innodb_stats_persistent;
set @innodb_stats_persistent_sample_pages_save=
@@innodb_stats_persistent_sample_pages;
set global innodb_stats_persistent= 1;
set global innodb_stats_persistent_sample_pages=100;
set optimizer_use_condition_selectivity=1;
analyze SELECT sysapproval_approver0.`sys_id`
FROM ((sysapproval_approver sysapproval_approver0
INNER JOIN task task1
ON sysapproval_approver0.`sysapproval` = task1.`sys_id`
AND (( task1.`sys_domain_path` = '/'
OR task1.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
OR task1.`sys_domain_path` LIKE '!!!/!!!/%' )))
INNER JOIN task task2
ON task1.`parent` = task2.`sys_id`
AND (( task2.`sys_domain_path` = '/'
OR task2.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
OR task2.`sys_domain_path` LIKE '!!!/!!!/%' )))
WHERE task2.`sys_id` LIKE '8e7792a7dbfffb00fff8a345ca961934%'
AND ( sysapproval_approver0.`sys_domain_path` = '/'
OR sysapproval_approver0.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
OR sysapproval_approver0.`sys_domain_path` LIKE '!!!/!!!/%' )
ORDER BY sysapproval_approver0.`order`
LIMIT 0, 50 ;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
1 SIMPLE task2 range PRIMARY,sys_class_name_2,sys_domain_path PRIMARY 96 NULL 1 0.00 100.00 100.00 Using where; Using temporary; Using filesort
1 SIMPLE task1 ref PRIMARY,task_parent,sys_class_name_2,sys_domain_path task_parent 99 mdev25830.task2.sys_id 1 NULL 100.00 NULL Using index condition; Using where
1 SIMPLE sysapproval_approver0 ref sysapproval_approver_ref5,sys_domain_path,sysapproval_approver_CHG1975376 sysapproval_approver_ref5 99 mdev25830.task1.sys_id 1 NULL 100.00 NULL Using index condition; Using where
set optimizer_use_condition_selectivity=4;
analyze SELECT sysapproval_approver0.`sys_id`
FROM ((sysapproval_approver sysapproval_approver0
INNER JOIN task task1
ON sysapproval_approver0.`sysapproval` = task1.`sys_id`
AND (( task1.`sys_domain_path` = '/'
OR task1.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
OR task1.`sys_domain_path` LIKE '!!!/!!!/%' )))
INNER JOIN task task2
ON task1.`parent` = task2.`sys_id`
AND (( task2.`sys_domain_path` = '/'
OR task2.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
OR task2.`sys_domain_path` LIKE '!!!/!!!/%' )))
WHERE task2.`sys_id` LIKE '8e7792a7dbfffb00fff8a345ca961934%'
AND ( sysapproval_approver0.`sys_domain_path` = '/'
OR sysapproval_approver0.`sys_domain_path` LIKE '!!!/!!#/!!$/%'
OR sysapproval_approver0.`sys_domain_path` LIKE '!!!/!!!/%' )
ORDER BY sysapproval_approver0.`order`
LIMIT 0, 50 ;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
1 SIMPLE task2 range PRIMARY,sys_class_name_2,sys_domain_path PRIMARY 96 NULL 1 0.00 98.00 100.00 Using where; Using temporary; Using filesort
1 SIMPLE task1 ref PRIMARY,task_parent,sys_class_name_2,sys_domain_path task_parent 99 mdev25830.task2.sys_id 1 NULL 100.00 NULL Using index condition; Using where
1 SIMPLE sysapproval_approver0 ref sysapproval_approver_ref5,sys_domain_path,sysapproval_approver_CHG1975376 sysapproval_approver_ref5 99 mdev25830.task1.sys_id 1 NULL 100.00 NULL Using index condition; Using where
set global innodb_stats_persistent= @innodb_stats_persistent_save;
set global innodb_stats_persistent_sample_pages=
@innodb_stats_persistent_sample_pages_save;
mysql-test/main/mdev-25830.test 0 → 100644
View file @ fdec8852
This diff is collapsed.
mysql-test/main/opt_trace_index_merge_innodb.result
View file @ fdec8852
......@@ -183,13 +183,13 @@ explain select * from t1 where pk1 != 0 and key1 = 1 {
},
{
"selectivity_for_indexes": [
{
"index_name": "PRIMARY",
"selectivity_from_index": 1
},
{
"index_name": "key1",
"selectivity_from_index": 0.001
},
{
"index_name": "PRIMARY",
"selectivity_from_index": 1
}
],
"selectivity_for_columns": [],
......
sql/opt_range.cc
View file @ fdec8852
......@@ -3249,6 +3249,25 @@ double records_in_column_ranges(PARAM *param, uint idx,
}
/*
Compare quick select ranges according to number of found rows
If there is equal amounts of rows, use the long key part.
The idea is that if we have keys (a),(a,b) and (a,b,c) and we have
a query like WHERE a=1 and b=1 and c=1,
it is better to use key (a,b,c) than (a) as it will ensure we don't also
use histograms for columns b and c
*/
static
int cmp_quick_ranges(TABLE *table, uint *a, uint *b)
{
int tmp= CMP_NUM(table->quick_rows[*a], table->quick_rows[*b]);
if (tmp)
return tmp;
return -CMP_NUM(table->quick_key_parts[*a], table->quick_key_parts[*b]);
}
/*
Calculate the selectivity of the condition imposed on the rows of a table
......@@ -3285,10 +3304,10 @@ double records_in_column_ranges(PARAM *param, uint idx,
bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item **cond)
{
uint keynr;
uint max_quick_key_parts= 0;
uint keynr, range_index, ranges;
MY_BITMAP *used_fields= &table->cond_set;
double table_records= (double)table->stat_records();
double table_records= (double)table->stat_records();
uint optimal_key_order[MAX_KEY];
DBUG_ENTER("calculate_cond_selectivity_for_table");
table->cond_selectivity= 1.0;
......@@ -3327,23 +3346,21 @@ bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item **cond)
Json_writer_object trace_wrapper(thd);
Json_writer_array selectivity_for_indexes(thd, "selectivity_for_indexes");
for (keynr= 0; keynr < table->s->keys; keynr++)
{
/*
Walk through all quick ranges in the order of least found rows.
*/
for (ranges= keynr= 0 ; keynr < table->s->keys; keynr++)
if (table->quick_keys.is_set(keynr))
set_if_bigger(max_quick_key_parts, table->quick_key_parts[keynr]);
}
optimal_key_order[ranges++]= keynr;
/*
Walk through all indexes, indexes where range access uses more keyparts
go first.
*/
for (uint quick_key_parts= max_quick_key_parts;
quick_key_parts; quick_key_parts--)
my_qsort2(optimal_key_order, ranges,
sizeof(optimal_key_order[0]),
(qsort2_cmp) cmp_quick_ranges, table);
for (range_index= 0 ; range_index < ranges ; range_index++)
{
for (keynr= 0; keynr < table->s->keys; keynr++)
uint keynr= optimal_key_order[range_index];
{
if (table->quick_keys.is_set(keynr) &&
table->quick_key_parts[keynr] == quick_key_parts)
{
uint i;
uint used_key_parts= table->quick_key_parts[keynr];
......
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