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MDEV-22191: Range access is not picked when index_merge_sort_union is turned off

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When index_merge_sort_union is turned off only ror scans were considered for range
scans, which is wrong.
To fix the problem ensure both ror scans and non ror scans are considered for range
access
This commit is contained in:
Varun Gupta 2020-04-08 17:39:27 +05:30
parent 64b70b09e6
commit c1394ab6b5
4 changed files with 62 additions and 6 deletions
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19
mysql-test/r/range.result
View file

@ -2144,3 +2144,22 @@ value1 1000685 12345
value1 1003560 12345
value1 1004807 12345
drop table t1;
#
# MDEV-22191: Range access is not picked when index_merge_sort_union is turned off
#
set @save_optimizer_switch=@@optimizer_switch;
set @save_optimizer_switch="index_merge_sort_union=OFF";
CREATE TABLE t1 (a INT, INDEX(a));
INSERT INTO t1 VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
explain
SELECT * FROM t1 WHERE a > 5;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 5 Using where; Using index
SELECT * FROM t1 WHERE a > 5;
a
6
7
8
9
set @@optimizer_switch=@save_optimizer_switch;
drop table t1;

19
mysql-test/r/range_mrr_icp.result
View file

@ -2146,4 +2146,23 @@ value1 1000685 12345
value1 1003560 12345
value1 1004807 12345
drop table t1;
#
# MDEV-22191: Range access is not picked when index_merge_sort_union is turned off
#
set @save_optimizer_switch=@@optimizer_switch;
set @save_optimizer_switch="index_merge_sort_union=OFF";
CREATE TABLE t1 (a INT, INDEX(a));
INSERT INTO t1 VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
explain
SELECT * FROM t1 WHERE a > 5;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range a a 5 NULL 5 Using where; Using index
SELECT * FROM t1 WHERE a > 5;
a
6
7
8
9
set @@optimizer_switch=@save_optimizer_switch;
drop table t1;
set optimizer_switch=@mrr_icp_extra_tmp;

14
mysql-test/t/range.test
View file

@ -1718,3 +1718,17 @@ where (key1varchar='value1' AND (key2int <=1 OR key2int > 1));
--echo # The following must show col1=12345 for all rows:
select * from t1;
drop table t1;
--echo #
--echo # MDEV-22191: Range access is not picked when index_merge_sort_union is turned off
--echo #
set @save_optimizer_switch=@@optimizer_switch;
set @save_optimizer_switch="index_merge_sort_union=OFF";
CREATE TABLE t1 (a INT, INDEX(a));
INSERT INTO t1 VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
explain
SELECT * FROM t1 WHERE a > 5;
SELECT * FROM t1 WHERE a > 5;
set @@optimizer_switch=@save_optimizer_switch;
drop table t1;

16
sql/opt_range.cc
View file

@ -949,7 +949,8 @@ QUICK_RANGE_SELECT *get_quick_select(PARAM *param,uint index,
static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
bool index_read_must_be_used,
bool update_tbl_stats,
double read_time);
double read_time,
bool ror_scans_required);
static
TRP_INDEX_INTERSECT *get_best_index_intersect(PARAM *param, SEL_TREE *tree,
double read_time);
@ -3146,7 +3147,7 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
/* Get best 'range' plan and prepare data for making other plans */
if ((range_trp= get_key_scans_params(&param, tree, FALSE, TRUE,
best_read_time)))
best_read_time, FALSE)))
{
best_trp= range_trp;
best_read_time= best_trp->read_cost;
@ -4708,7 +4709,8 @@ TABLE_READ_PLAN *get_best_disjunct_quick(PARAM *param, SEL_IMERGE *imerge,
{
DBUG_EXECUTE("info", print_sel_tree(param, *ptree, &(*ptree)->keys_map,
"tree in SEL_IMERGE"););
if (!(*cur_child= get_key_scans_params(param, *ptree, TRUE, FALSE, read_time)))
if (!(*cur_child= get_key_scans_params(param, *ptree, TRUE, FALSE,
read_time, TRUE)))
{
/*
One of index scans in this index_merge is more expensive than entire
@ -5030,7 +5032,7 @@ TABLE_READ_PLAN *merge_same_index_scans(PARAM *param, SEL_IMERGE *imerge,
index merge retrievals are not well calibrated
*/
trp= get_key_scans_params(param, *imerge->trees, FALSE, TRUE,
read_time);
read_time, TRUE);
}
DBUG_RETURN(trp);
@ -6747,6 +6749,7 @@ TRP_ROR_INTERSECT *get_best_covering_ror_intersect(PARAM *param,
index_read_must_be_used if TRUE, assume 'index only' option will be set
(except for clustered PK indexes)
read_time don't create read plans with cost > read_time.
ror_scans_required set to TRUE for index merge
RETURN
Best range read plan
NULL if no plan found or error occurred
@ -6755,7 +6758,8 @@ TRP_ROR_INTERSECT *get_best_covering_ror_intersect(PARAM *param,
static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
bool index_read_must_be_used,
bool update_tbl_stats,
double read_time)
double read_time,
bool ror_scans_required)
{
uint idx;
SEL_ARG **key,**end, **key_to_read= NULL;
@ -6802,7 +6806,7 @@ static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
update_tbl_stats, &mrr_flags,
&buf_size, &cost);
if (!param->is_ror_scan &&
if (ror_scans_required && !param->is_ror_scan &&
!optimizer_flag(param->thd, OPTIMIZER_SWITCH_INDEX_MERGE_SORT_UNION))
{
/* The scan is not a ROR-scan, just skip it */