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Commit 64046459 authored by Varun Gupta's avatar Varun Gupta
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MDEV-21626: Optimizer misses the details about the picked join order 

Added cost of sorting estimate to the optimizer trace
parent 80591481
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mysql-test/main/opt_trace.result
View file @ 64046459
......@@ -441,6 +441,7 @@ select * from v2 {
},
"rows_for_plan": 1,
"cost_for_plan": 2.4044,
"cost_for_sorting": 1,
"estimated_join_cardinality": 1
}
]
......@@ -765,6 +766,7 @@ explain select * from v1 {
},
"rows_for_plan": 10,
"cost_for_plan": 4.022,
"cost_for_sorting": 10,
"estimated_join_cardinality": 10
}
]
......@@ -1449,6 +1451,7 @@ EXPLAIN SELECT MIN(d) FROM t1 where b=2 and c=3 group by a {
},
"rows_for_plan": 0.5849,
"cost_for_plan": 3.4291,
"cost_for_sorting": 0.5849,
"estimated_join_cardinality": 0.5849
}
]
......@@ -1650,6 +1653,7 @@ EXPLAIN SELECT id,MIN(a),MAX(a) FROM t1 WHERE a>=20010104e0 GROUP BY id {
},
"rows_for_plan": 16,
"cost_for_plan": 5.2313,
"cost_for_sorting": 16,
"estimated_join_cardinality": 16
}
]
......@@ -1840,6 +1844,7 @@ EXPLAIN SELECT * FROM t1 WHERE a = 20010104e0 GROUP BY id {
},
"rows_for_plan": 16,
"cost_for_plan": 5.2313,
"cost_for_sorting": 16,
"estimated_join_cardinality": 16
}
]
......@@ -8292,5 +8297,173 @@ JSON_DETAILED(JSON_EXTRACT(trace, '$**.range_scan_alternatives'))
]
]
drop table t1;
#
# MDEV-21626: Optimizer misses the details about the picked join order
#
CREATE TABLE t1(a INT, b INT, key(a));
INSERT INTO t1 SELECT seq, seq from seq_1_to_10;
CREATE TABLE t2(a INT, b INT, key(a));
INSERT INTO t2 SELECT seq, seq from seq_1_to_100;
SET OPTIMIZER_TRACE=1;
EXPLAIN SELECT * FROM t1, t2 WHERE t1.a=t2.a ORDER BY t2.b;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL a NULL NULL NULL 10 Using where; Using temporary; Using filesort
1 SIMPLE t2 ref a a 5 test.t1.a 1
select JSON_DETAILED(JSON_EXTRACT(trace, '$**.considered_execution_plans')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
JSON_DETAILED(JSON_EXTRACT(trace, '$**.considered_execution_plans'))
[
[
{
"plan_prefix":
[
],
"table": "t1",
"best_access_path":
{
"considered_access_paths":
[
{
"access_type": "scan",
"resulting_rows": 10,
"cost": 2.022,
"chosen": true
}
],
"chosen_access_method":
{
"type": "scan",
"records": 10,
"cost": 2.022,
"uses_join_buffering": false
}
},
"rows_for_plan": 10,
"cost_for_plan": 4.022,
"rest_of_plan":
[
{
"plan_prefix":
[
"t1"
],
"table": "t2",
"best_access_path":
{
"considered_access_paths":
[
{
"access_type": "ref",
"index": "a",
"used_range_estimates": false,
"cause": "not available",
"rows": 1,
"cost": 20,
"chosen": true
},
{
"access_type": "scan",
"resulting_rows": 100,
"cost": 2.2197,
"chosen": false
}
],
"chosen_access_method":
{
"type": "ref",
"records": 1,
"cost": 20,
"uses_join_buffering": false
}
},
"rows_for_plan": 10,
"cost_for_plan": 26.022,
"cost_for_sorting": 10,
"estimated_join_cardinality": 10
}
]
},
{
"plan_prefix":
[
],
"table": "t2",
"best_access_path":
{
"considered_access_paths":
[
{
"access_type": "scan",
"resulting_rows": 100,
"cost": 2.2197,
"chosen": true,
"use_tmp_table": true
}
],
"chosen_access_method":
{
"type": "scan",
"records": 100,
"cost": 2.2197,
"uses_join_buffering": false
}
},
"rows_for_plan": 100,
"cost_for_plan": 22.22,
"rest_of_plan":
[
{
"plan_prefix":
[
"t2"
],
"table": "t1",
"best_access_path":
{
"considered_access_paths":
[
{
"access_type": "ref",
"index": "a",
"used_range_estimates": false,
"cause": "not available",
"rows": 1,
"cost": 200,
"chosen": true
},
{
"access_type": "scan",
"resulting_rows": 10,
"cost": 2.022,
"chosen": true
}
],
"chosen_access_method":
{
"type": "scan",
"records": 10,
"cost": 2.022,
"uses_join_buffering": true
}
},
"rows_for_plan": 1000,
"cost_for_plan": 224.24,
"pruned_by_cost": true
}
]
}
]
]
DROP TABLE t1,t2;
# End of 10.4 tests
set optimizer_trace='enabled=off';
mysql-test/main/opt_trace.test
View file @ 64046459
--source include/not_embedded.inc
--source include/have_sequence.inc
SELECT table_name, column_name FROM information_schema.columns where table_name="OPTIMIZER_TRACE";
show variables like 'optimizer_trace';
set optimizer_trace="enabled=on";
......@@ -579,6 +580,20 @@ select * from t1 force index(kp1) where (kp1=2 and kp2 >=4);
select JSON_DETAILED(JSON_EXTRACT(trace, '$**.range_scan_alternatives')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
drop table t1;
--echo #
--echo # MDEV-21626: Optimizer misses the details about the picked join order
--echo #
CREATE TABLE t1(a INT, b INT, key(a));
INSERT INTO t1 SELECT seq, seq from seq_1_to_10;
CREATE TABLE t2(a INT, b INT, key(a));
INSERT INTO t2 SELECT seq, seq from seq_1_to_100;
SET OPTIMIZER_TRACE=1;
EXPLAIN SELECT * FROM t1, t2 WHERE t1.a=t2.a ORDER BY t2.b;
select JSON_DETAILED(JSON_EXTRACT(trace, '$**.considered_execution_plans')) from INFORMATION_SCHEMA.OPTIMIZER_TRACE;
DROP TABLE t1,t2;
--echo # End of 10.4 tests
set optimizer_trace='enabled=off';
sql/sql_select.cc
View file @ 64046459
......@@ -9593,12 +9593,15 @@ best_extension_by_limited_search(JOIN *join,
if (join->sort_by_table &&
join->sort_by_table !=
join->positions[join->const_tables].table->table)
{
/*
We may have to make a temp table, note that this is only a
heuristic since we cannot know for sure at this point.
Hence it may be wrong.
*/
trace_one_table.add("cost_for_sorting", current_record_count);
current_read_time= COST_ADD(current_read_time, current_record_count);
}
trace_one_table.add("estimated_join_cardinality",
partial_join_cardinality);
if (current_read_time < join->best_read)
......
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