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MDEV-23767: IN-to-subquery conversion is not visible in optimizer trace

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Add the printout
This commit is contained in:
Sergei Petrunia
2020-09-20 00:07:37 +03:00
parent ccbe6bb6fc
commit 29a6d23622
3 changed files with 148 additions and 2 deletions
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98
mysql-test/main/opt_trace.result
View File

@@ -8684,5 +8684,103 @@ JSON_DETAILED(JSON_EXTRACT(trace, '$**.mark_join_nest_as_const'))
}
]
drop table t0, t1, t2, t3;
#
# MDEV-23767: IN-to-subquery conversion is not visible in optimizer trace
#
create table t0 (a int);
INSERT INTO t0 VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
set @tmp=@@in_predicate_conversion_threshold;
set in_predicate_conversion_threshold=3;
explain select * from t0 where a in (1,2,3,4,5,6);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t0 ALL NULL NULL NULL NULL 10 Using where
1 PRIMARY <derived3> ref key0 key0 4 test.t0.a 2 FirstMatch(t0)
3 DERIVED NULL NULL NULL NULL NULL NULL NULL No tables used
select json_detailed(json_extract(trace, '$**.in_to_subquery_conversion'))
from information_schema.optimizer_trace;
json_detailed(json_extract(trace, '$**.in_to_subquery_conversion'))
[
{
"item": "t0.a in (1,2,3,4,5,6)",
"conversion":
[
{
"join_preparation":
{
"select_id": 2,
"steps":
[
{
"derived":
{
"table": "tvc_0",
"select_id": 3,
"algorithm": "materialized"
}
},
{
"transformation":
{
"select_id": 2,
"from": "IN (SELECT)",
"to": "materialization",
"sjm_scan_allowed": true,
"possible": true
}
},
{
"transformation":
{
"select_id": 2,
"from": "IN (SELECT)",
"to": "semijoin",
"chosen": true
}
},
{
"expanded_query": "/* select#2 */ select tvc_0._col_1 from (values (1),(2),(3),(4),(5),(6)) tvc_0"
}
]
}
}
]
}
]
explain select * from t0 where a in (1,2,3,4,5,a+1);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 10 Using where
select json_detailed(json_extract(trace, '$**.in_to_subquery_conversion'))
from information_schema.optimizer_trace;
json_detailed(json_extract(trace, '$**.in_to_subquery_conversion'))
[
{
"item": "t0.a in (1,2,3,4,5,t0.a + 1)",
"done": false,
"reason": "non-constant element in the IN-list"
}
]
explain select * from t0 where a in ('1','2','3','4','5','6');
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t0 ALL NULL NULL NULL NULL 10 Using where
select json_detailed(json_extract(trace, '$**.in_to_subquery_conversion'))
from information_schema.optimizer_trace;
json_detailed(json_extract(trace, '$**.in_to_subquery_conversion'))
[
{
"item": "t0.a in ('1','2','3','4','5','6')",
"done": false,
"reason": "type mismatch"
}
]
set in_predicate_conversion_threshold=@tmp;
drop table t0;
# End of 10.5 tests
set optimizer_trace='enabled=off';

26
mysql-test/main/opt_trace.test
View File

@@ -654,5 +654,31 @@ from information_schema.optimizer_trace;
drop table t0, t1, t2, t3;
--echo #
--echo # MDEV-23767: IN-to-subquery conversion is not visible in optimizer trace
--echo #
create table t0 (a int);
INSERT INTO t0 VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
set @tmp=@@in_predicate_conversion_threshold;
set in_predicate_conversion_threshold=3;
explain select * from t0 where a in (1,2,3,4,5,6);
select json_detailed(json_extract(trace, '$**.in_to_subquery_conversion'))
from information_schema.optimizer_trace;
explain select * from t0 where a in (1,2,3,4,5,a+1);
select json_detailed(json_extract(trace, '$**.in_to_subquery_conversion'))
from information_schema.optimizer_trace;
explain select * from t0 where a in ('1','2','3','4','5','6');
select json_detailed(json_extract(trace, '$**.in_to_subquery_conversion'))
from information_schema.optimizer_trace;
set in_predicate_conversion_threshold=@tmp;
drop table t0;
--echo # End of 10.5 tests
set optimizer_trace='enabled=off';

24
sql/sql_tvc.cc
View File

@@ -22,6 +22,7 @@
#include "sql_explain.h"
#include "sql_parse.h"
#include "sql_cte.h"
#include "my_json_writer.h"
/**
@@ -903,6 +904,10 @@ Item *Item_func_in::in_predicate_to_in_subs_transformer(THD *thd,
if (!transform_into_subq)
return this;
Json_writer_object trace_wrapper(thd);
Json_writer_object trace_conv(thd, "in_to_subquery_conversion");
trace_conv.add("item", this);
transform_into_subq= false;
List<List_item> values;
@@ -922,14 +927,30 @@ Item *Item_func_in::in_predicate_to_in_subs_transformer(THD *thd,
uint32 length= max_length_of_left_expr();
if (!length || length > tmp_table_max_key_length() ||
args[0]->cols() > tmp_table_max_key_parts())
{
trace_conv.add("done", false);
trace_conv.add("reason", "key is too long");
return this;
}
for (uint i=1; i < arg_count; i++)
{
if (!args[i]->const_item() || cmp_row_types(args[0], args[i]))
if (!args[i]->const_item())
{
trace_conv.add("done", false);
trace_conv.add("reason", "non-constant element in the IN-list");
return this;
}
if (cmp_row_types(args[0], args[i]))
{
trace_conv.add("done", false);
trace_conv.add("reason", "type mismatch");
return this;
}
}
Json_writer_array trace_nested_obj(thd, "conversion");
Query_arena backup;
Query_arena *arena= thd->activate_stmt_arena_if_needed(&backup);
@@ -1020,6 +1041,7 @@ Item *Item_func_in::in_predicate_to_in_subs_transformer(THD *thd,
goto err;
parent_select->curr_tvc_name++;
return sq;
err: