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mariadb/mysql-test/r/explain_json.result
Varun Gupta 9419908f38 MDEV-15433: Optimizer does not use group by optimization with distinct 
After the commit b76b69cd5f
loose index scan for queries with DISTINCT stopped working.
That is why that commit has to be reverted.
Additionally this patch  fixes the problem of MDEV-10880.
2018-08-05 13:25:40 +03:00

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drop table if exists t0,t1,t2;
create table t0(a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
explain format=json select * from t0;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
explain format=json select * from t0 where 1>2;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"message": "Impossible WHERE"
}
}
}
explain format=json select * from t0 where a<3;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t0.a < 3)"
}
}
}
# Try a basic join
create table t1 (a int, b int, filler char(32), key(a));
insert into t1
select
a.a + b.a* 10 + c.a * 100,
a.a + b.a* 10 + c.a * 100,
'filler'
from t0 a, t0 b, t0 c;
explain format=json select * from t0,t1 where t1.a=t0.a;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t0.a is not null)"
},
"table": {
"table_name": "t1",
"access_type": "ref",
"possible_keys": ["a"],
"key": "a",
"key_length": "5",
"used_key_parts": ["a"],
"ref": ["test.t0.a"],
"rows": 1,
"filtered": 100
}
}
}
# Try range and index_merge
create table t2 (a1 int, a2 int, b1 int, b2 int, key(a1,a2), key(b1,b2));
insert into t2 select a,a,a,a from t1;
explain format=json select * from t2 where a1<5;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "range",
"possible_keys": ["a1"],
"key": "a1",
"key_length": "5",
"used_key_parts": ["a1"],
"rows": 5,
"filtered": 100,
"index_condition": "(t2.a1 < 5)"
}
}
}
explain format=json select * from t2 where a1=1 or b1=2;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "index_merge",
"possible_keys": ["a1", "b1"],
"key_length": "5,5",
"index_merge": {
"sort_union": {
"range": {
"key": "a1",
"used_key_parts": ["a1"]
},
"range": {
"key": "b1",
"used_key_parts": ["b1"]
}
}
},
"rows": 2,
"filtered": 100,
"attached_condition": "((t2.a1 = 1) or (t2.b1 = 2))"
}
}
}
explain format=json select * from t2 where a1=1 or (b1=2 and b2=3);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "index_merge",
"possible_keys": ["a1", "b1"],
"key_length": "5,10",
"index_merge": {
"sort_union": {
"range": {
"key": "a1",
"used_key_parts": ["a1"]
},
"range": {
"key": "b1",
"used_key_parts": ["b1", "b2"]
}
}
},
"rows": 2,
"filtered": 100,
"attached_condition": "((t2.a1 = 1) or ((t2.b1 = 2) and (t2.b2 = 3)))"
}
}
}
explain format=json select * from t2 where (a1=1 and a2=1) or
(b1=2 and b2=1);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "index_merge",
"possible_keys": ["a1", "b1"],
"key_length": "10,10",
"index_merge": {
"union": {
"range": {
"key": "a1",
"used_key_parts": ["a1", "a2"]
},
"range": {
"key": "b1",
"used_key_parts": ["b1", "b2"]
}
}
},
"rows": 2,
"filtered": 100,
"attached_condition": "(((t2.a1 = 1) and (t2.a2 = 1)) or ((t2.b1 = 2) and (t2.b2 = 1)))"
}
}
}
# Try ref access on two key components
explain format=json select * from t0,t2 where t2.b1=t0.a and t2.b2=4;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t0.a is not null)"
},
"table": {
"table_name": "t2",
"access_type": "ref",
"possible_keys": ["b1"],
"key": "b1",
"key_length": "10",
"used_key_parts": ["b1", "b2"],
"ref": ["test.t0.a", "const"],
"rows": 1,
"filtered": 100
}
}
}
drop table t1,t2;
#
# Try a UNION
#
explain format=json select * from t0 A union select * from t0 B;
EXPLAIN
{
"query_block": {
"union_result": {
"table_name": "<union1,2>",
"access_type": "ALL",
"query_specifications": [
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "A",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
},
{
"query_block": {
"select_id": 2,
"table": {
"table_name": "B",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
]
}
}
}
explain format=json select * from t0 A union all select * from t0 B;
EXPLAIN
{
"query_block": {
"union_result": {
"table_name": "<union1,2>",
"access_type": "ALL",
"query_specifications": [
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "A",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
},
{
"query_block": {
"select_id": 2,
"table": {
"table_name": "B",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
]
}
}
}
#
# Subqueries
#
create table t1 (a int, b int);
insert into t1 select a,a from t0;
explain format=json select a, a > (select max(b) from t1 where t1.b=t0.a) from t0;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100
},
"subqueries": [
{
"expression_cache": {
"state": "uninitialized",
"query_block": {
"select_id": 2,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t1.b = t0.a)"
}
}
}
}
]
}
}
explain format=json
select * from t0 where
a > (select max(b) from t1 where t1.b=t0.a) or a < 3 ;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "((t0.a > (subquery#2)) or (t0.a < 3))"
},
"subqueries": [
{
"expression_cache": {
"state": "uninitialized",
"query_block": {
"select_id": 2,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t1.b = t0.a)"
}
}
}
}
]
}
}
drop table t1;
#
# Join buffering
#
create table t1 (a int, b int);
insert into t1 select tbl1.a+10*tbl2.a, tbl1.a+10*tbl2.a from t0 tbl1, t0 tbl2;
explain format=json
select * from t1 tbl1, t1 tbl2 where tbl1.a=tbl2.a and tbl1.b < 3 and tbl2.b < 5;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "tbl1",
"access_type": "ALL",
"rows": 100,
"filtered": 100,
"attached_condition": "(tbl1.b < 3)"
},
"block-nl-join": {
"table": {
"table_name": "tbl2",
"access_type": "ALL",
"rows": 100,
"filtered": 100,
"attached_condition": "(tbl2.b < 5)"
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BNL",
"attached_condition": "(tbl2.a = tbl1.a)"
}
}
}
drop table t1;
#
# Single-table UPDATE/DELETE, INSERT
#
explain format=json delete from t0;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"message": "Deleting all rows"
}
}
}
explain format=json delete from t0 where 1 > 2;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"message": "Impossible WHERE"
}
}
}
explain format=json delete from t0 where a < 3;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"delete": 1,
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"attached_condition": "(t0.a < 3)"
}
}
}
explain format=json update t0 set a=3 where a in (2,3,4);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"update": 1,
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"attached_condition": "(t0.a in (2,3,4))"
}
}
}
explain format=json insert into t0 values (1);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t0"
}
}
}
create table t1 like t0;
explain format=json insert into t1 values ((select max(a) from t0));
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1"
},
"subqueries": [
{
"query_block": {
"select_id": 2,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
]
}
}
drop table t1;
#
# A derived table
#
create table t1 (a int, b int);
insert into t1 select a,a from t0;
explain format=json
select * from (select a, count(*) as cnt from t1 group by a) as tbl
where cnt>0;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "<derived2>",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(tbl.cnt > 0)",
"materialized": {
"query_block": {
"select_id": 2,
"filesort": {
"temporary_table": {
"function": "buffer",
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
}
}
}
}
}
explain format=json
select * from (select a, count(*) as cnt from t1 group by a) as tbl1, t1 as
tbl2 where cnt=tbl2.a;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "tbl2",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(tbl2.a is not null)"
},
"table": {
"table_name": "<derived2>",
"access_type": "ref",
"possible_keys": ["key0"],
"key": "key0",
"key_length": "8",
"used_key_parts": ["cnt"],
"ref": ["test.tbl2.a"],
"rows": 2,
"filtered": 100,
"attached_condition": "(tbl1.cnt = tbl2.a)",
"materialized": {
"query_block": {
"select_id": 2,
"filesort": {
"temporary_table": {
"function": "buffer",
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
}
}
}
}
}
#
# Non-merged semi-join (aka JTBM)
#
explain format=json
select * from t1 where a in (select max(a) from t1 group by b);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t1.a is not null)"
},
"table": {
"table_name": "<subquery2>",
"access_type": "eq_ref",
"possible_keys": ["distinct_key"],
"key": "distinct_key",
"key_length": "4",
"used_key_parts": ["max(a)"],
"ref": ["test.t1.a"],
"rows": 1,
"filtered": 100,
"materialized": {
"unique": 1,
"query_block": {
"select_id": 2,
"temporary_table": {
"function": "buffer",
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
}
}
}
}
#
# Semi-join Materialization
#
create table t2 like t1;
insert into t2 select * from t1;
explain format=json
select * from t1,t2 where t1.a in ( select a from t0);
EXPLAIN
{
"query_block": {
"select_id": 1,
"const_condition": "1",
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100
},
"table": {
"table_name": "<subquery2>",
"access_type": "eq_ref",
"possible_keys": ["distinct_key"],
"key": "distinct_key",
"key_length": "4",
"used_key_parts": ["a"],
"ref": ["func"],
"rows": 1,
"filtered": 100,
"materialized": {
"unique": 1,
"query_block": {
"select_id": 2,
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100
}
}
}
},
"block-nl-join": {
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 10,
"filtered": 100
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BNL"
}
}
}
#
# First-Match
#
explain
select * from t2 where t2.a in ( select a from t1 where t1.b=t2.b);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 10
1 PRIMARY t1 ALL NULL NULL NULL NULL 10 Using where; FirstMatch(t2); Using join buffer (flat, BNL join)
explain format=json
select * from t2 where t2.a in ( select a from t1 where t1.b=t2.b);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 10,
"filtered": 100
},
"block-nl-join": {
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"first_match": "t2"
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BNL",
"attached_condition": "((t1.b = t2.b) and (t1.a = t2.a))"
}
}
}
#
# Duplicate Weedout
#
set @tmp= @@optimizer_switch;
set optimizer_switch='firstmatch=off';
explain
select * from t2 where t2.a in ( select a from t1 where t1.b=t2.b);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 ALL NULL NULL NULL NULL 10
1 PRIMARY t1 ALL NULL NULL NULL NULL 10 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join)
explain format=json
select * from t2 where t2.a in ( select a from t1 where t1.b=t2.b);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 10,
"filtered": 100
},
"duplicates_removal": {
"block-nl-join": {
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 10,
"filtered": 100
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BNL",
"attached_condition": "((t1.b = t2.b) and (t1.a = t2.a))"
}
}
}
}
set optimizer_switch=@tmp;
drop table t1,t2;
#
# MRR for range access (no BKA, just MRR)
#
create table t1 (a int, b int, key(a));
insert into t1 select tbl1.a+10*tbl2.a, 12345 from t0 tbl1, t0 tbl2;
set @tmp= @@optimizer_switch;
set optimizer_switch='mrr=on,mrr_sort_keys=on';
explain format=json select * from t1 where a < 3;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "range",
"possible_keys": ["a"],
"key": "a",
"key_length": "5",
"used_key_parts": ["a"],
"rows": 1,
"filtered": 100,
"index_condition": "(t1.a < 3)",
"mrr_type": "Rowid-ordered scan"
}
}
}
# 'Range checked for each record'
set optimizer_switch=@tmp;
explain format=json
select * from t1 tbl1, t1 tbl2 where tbl2.a < tbl1.b;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "tbl1",
"access_type": "ALL",
"rows": 100,
"filtered": 100
},
"range-checked-for-each-record": {
"keys": ["a"],
"table": {
"table_name": "tbl2",
"access_type": "ALL",
"possible_keys": ["a"],
"rows": 100,
"filtered": 100
}
}
}
}
drop table t1;
drop table t0;
#
# MDEV-7265: "Full scan on NULL key", the join case
#
CREATE TABLE t1 (a INT, KEY(a));
INSERT INTO t1 VALUES (1),(2);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (3),(4);
EXPLAIN FORMAT=JSON SELECT * FROM t1 AS outer_t1 WHERE a <> ALL ( SELECT a FROM t1, t2 WHERE b <> outer_t1.a );
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "outer_t1",
"access_type": "index",
"key": "a",
"key_length": "5",
"used_key_parts": ["a"],
"rows": 2,
"filtered": 100,
"attached_condition": "(not(<in_optimizer>(outer_t1.a,<exists>(subquery#2))))",
"using_index": true
},
"subqueries": [
{
"query_block": {
"select_id": 2,
"having_condition": "trigcond(<is_not_null_test>(t1.a))",
"full-scan-on-null_key": {
"table": {
"table_name": "t1",
"access_type": "ref_or_null",
"possible_keys": ["a"],
"key": "a",
"key_length": "5",
"used_key_parts": ["a"],
"ref": ["func"],
"rows": 2,
"filtered": 100,
"attached_condition": "trigcond(((<cache>(outer_t1.a) = t1.a) or isnull(t1.a)))",
"using_index": true
}
},
"block-nl-join": {
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 2,
"filtered": 100
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BNL",
"attached_condition": "(t2.b <> outer_t1.a)"
}
}
}
]
}
}
DROP TABLE t1,t2;
#
# Join's constant expression
#
create table t0(a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1(a int, b int);
insert into t1 select tbl1.a+10*tbl2.a, 1234 from t0 tbl1, t0 tbl2;
explain format=json
select * from t0
where
20000 > all (select max(tbl1.a + tbl2.a)
from t1 tbl1, t1 tbl2 where tbl1.b=tbl2.b);
EXPLAIN
{
"query_block": {
"select_id": 1,
"const_condition": "<not>(<in_optimizer>(20000,(<max>(subquery#2) >= 20000)))",
"table": {
"table_name": "t0",
"access_type": "ALL",
"rows": 10,
"filtered": 100
},
"subqueries": [
{
"query_block": {
"select_id": 2,
"table": {
"table_name": "tbl1",
"access_type": "ALL",
"rows": 100,
"filtered": 100
},
"block-nl-join": {
"table": {
"table_name": "tbl2",
"access_type": "ALL",
"rows": 100,
"filtered": 100
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BNL",
"attached_condition": "(tbl2.b = tbl1.b)"
}
}
}
]
}
}
drop table t1;
drop table t0;
#
# MDEV-7264: Assertion `0' failed in subselect_engine::get_identifier() on EXPLAIN JSON
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(2);
CREATE TABLE t2 (b INT);
INSERT INTO t2 VALUES (3),(4);
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a <> ALL ( SELECT b FROM t2 );
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 2,
"filtered": 100,
"attached_condition": "(not(<in_optimizer>(t1.a,t1.a in (subquery#2))))"
},
"subqueries": [
{
"query_block": {
"select_id": 2,
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 2,
"filtered": 100
}
}
}
]
}
}
DROP TABLE t1, t2;
#
# MDEV-7927: Server crashes in in Time_and_counter_tracker::incr_loops
#
CREATE TABLE t1 (i INT);
INSERT INTO t1 VALUES (1),(2);
EXPLAIN SELECT * FROM t1 WHERE 3 IN ( SELECT 4 UNION SELECT 5 );
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
2 SUBQUERY NULL NULL NULL NULL NULL NULL NULL No tables used
3 UNION NULL NULL NULL NULL NULL NULL NULL No tables used
NULL UNION RESULT <union2,3> ALL NULL NULL NULL NULL NULL
DROP TABLE t1;
#
# MDEV-7860: EXPLAIN FORMAT=JSON crashes for loose scan query
#
create table t2(a int);
insert into t2 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1 (a int, b int, c int, d int, key(a,b,c));
insert into t1 select A.a, B.a, C.a, D.a from t2 A, t2 B, t2 C, t2 D;
explain select count(distinct b) from t1 group by a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL a 10 NULL 101 Using index for group-by
explain format=json select count(distinct b) from t1 group by a;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "range",
"key": "a",
"key_length": "10",
"used_key_parts": ["a", "b"],
"rows": 101,
"filtered": 100,
"using_index_for_group_by": true
}
}
}
analyze format=json select count(distinct b) from t1 group by a;
ANALYZE
{
"query_block": {
"select_id": 1,
"r_loops": 1,
"r_total_time_ms": "REPLACED",
"table": {
"table_name": "t1",
"access_type": "range",
"key": "a",
"key_length": "10",
"used_key_parts": ["a", "b"],
"r_loops": 1,
"rows": 101,
"r_rows": 100,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100,
"using_index_for_group_by": true
}
}
}
drop table t1,t2;
#
# Try both variants of LooseScan (data/queries borrowed from group_min_max.test)
#
create table t1 (
a1 char(64), a2 char(64), b char(16), c char(16) not null, d char(16), dummy char(248) default ' '
);
insert into t1 (a1, a2, b, c, d) values
('a','a','a','a111','xy1'),('a','a','a','b111','xy2'),('a','a','a','c111','xy3'),('a','a','a','d111','xy4'),
('a','a','b','e112','xy1'),('a','a','b','f112','xy2'),('a','a','b','g112','xy3'),('a','a','b','h112','xy4'),
('a','b','a','i121','xy1'),('a','b','a','j121','xy2'),('a','b','a','k121','xy3'),('a','b','a','l121','xy4'),
('a','b','b','m122','xy1'),('a','b','b','n122','xy2'),('a','b','b','o122','xy3'),('a','b','b','p122','xy4'),
('b','a','a','a211','xy1'),('b','a','a','b211','xy2'),('b','a','a','c211','xy3'),('b','a','a','d211','xy4'),
('b','a','b','e212','xy1'),('b','a','b','f212','xy2'),('b','a','b','g212','xy3'),('b','a','b','h212','xy4'),
('b','b','a','i221','xy1'),('b','b','a','j221','xy2'),('b','b','a','k221','xy3'),('b','b','a','l221','xy4'),
('b','b','b','m222','xy1'),('b','b','b','n222','xy2'),('b','b','b','o222','xy3'),('b','b','b','p222','xy4'),
('c','a','a','a311','xy1'),('c','a','a','b311','xy2'),('c','a','a','c311','xy3'),('c','a','a','d311','xy4'),
('c','a','b','e312','xy1'),('c','a','b','f312','xy2'),('c','a','b','g312','xy3'),('c','a','b','h312','xy4'),
('c','b','a','i321','xy1'),('c','b','a','j321','xy2'),('c','b','a','k321','xy3'),('c','b','a','l321','xy4'),
('c','b','b','m322','xy1'),('c','b','b','n322','xy2'),('c','b','b','o322','xy3'),('c','b','b','p322','xy4'),
('d','a','a','a411','xy1'),('d','a','a','b411','xy2'),('d','a','a','c411','xy3'),('d','a','a','d411','xy4'),
('d','a','b','e412','xy1'),('d','a','b','f412','xy2'),('d','a','b','g412','xy3'),('d','a','b','h412','xy4'),
('d','b','a','i421','xy1'),('d','b','a','j421','xy2'),('d','b','a','k421','xy3'),('d','b','a','l421','xy4'),
('d','b','b','m422','xy1'),('d','b','b','n422','xy2'),('d','b','b','o422','xy3'),('d','b','b','p422','xy4'),
('a','a','a','a111','xy1'),('a','a','a','b111','xy2'),('a','a','a','c111','xy3'),('a','a','a','d111','xy4'),
('a','a','b','e112','xy1'),('a','a','b','f112','xy2'),('a','a','b','g112','xy3'),('a','a','b','h112','xy4'),
('a','b','a','i121','xy1'),('a','b','a','j121','xy2'),('a','b','a','k121','xy3'),('a','b','a','l121','xy4'),
('a','b','b','m122','xy1'),('a','b','b','n122','xy2'),('a','b','b','o122','xy3'),('a','b','b','p122','xy4'),
('b','a','a','a211','xy1'),('b','a','a','b211','xy2'),('b','a','a','c211','xy3'),('b','a','a','d211','xy4'),
('b','a','b','e212','xy1'),('b','a','b','f212','xy2'),('b','a','b','g212','xy3'),('b','a','b','h212','xy4'),
('b','b','a','i221','xy1'),('b','b','a','j221','xy2'),('b','b','a','k221','xy3'),('b','b','a','l221','xy4'),
('b','b','b','m222','xy1'),('b','b','b','n222','xy2'),('b','b','b','o222','xy3'),('b','b','b','p222','xy4'),
('c','a','a','a311','xy1'),('c','a','a','b311','xy2'),('c','a','a','c311','xy3'),('c','a','a','d311','xy4'),
('c','a','b','e312','xy1'),('c','a','b','f312','xy2'),('c','a','b','g312','xy3'),('c','a','b','h312','xy4'),
('c','b','a','i321','xy1'),('c','b','a','j321','xy2'),('c','b','a','k321','xy3'),('c','b','a','l321','xy4'),
('c','b','b','m322','xy1'),('c','b','b','n322','xy2'),('c','b','b','o322','xy3'),('c','b','b','p322','xy4'),
('d','a','a','a411','xy1'),('d','a','a','b411','xy2'),('d','a','a','c411','xy3'),('d','a','a','d411','xy4'),
('d','a','b','e412','xy1'),('d','a','b','f412','xy2'),('d','a','b','g412','xy3'),('d','a','b','h412','xy4'),
('d','b','a','i421','xy1'),('d','b','a','j421','xy2'),('d','b','a','k421','xy3'),('d','b','a','l421','xy4'),
('d','b','b','m422','xy1'),('d','b','b','n422','xy2'),('d','b','b','o422','xy3'),('d','b','b','p422','xy4');
create index idx_t1_0 on t1 (a1);
create index idx_t1_1 on t1 (a1,a2,b,c);
create index idx_t1_2 on t1 (a1,a2,b);
analyze table t1;
Table Op Msg_type Msg_text
test.t1 analyze status Table is already up to date
explain select count(distinct a1,a2,b) from t1 where (a2 >= 'b') and (b = 'a');
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL idx_t1_1 147 NULL 17 Using where; Using index for group-by
explain select count(distinct a1,a2,b,c) from t1 where (a2 >= 'b') and (b = 'a') and (c = 'i121');
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range NULL idx_t1_1 163 NULL 65 Using where; Using index for group-by (scanning)
explain format=json select count(distinct a1,a2,b) from t1 where (a2 >= 'b') and (b = 'a');
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "range",
"key": "idx_t1_1",
"key_length": "147",
"used_key_parts": ["a1", "a2", "b"],
"rows": 17,
"filtered": 100,
"attached_condition": "((t1.b = 'a') and (t1.a2 >= 'b'))",
"using_index_for_group_by": true
}
}
}
explain format=json select count(distinct a1,a2,b,c) from t1 where (a2 >= 'b') and (b = 'a') and (c = 'i121');
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "range",
"key": "idx_t1_1",
"key_length": "163",
"used_key_parts": ["a1", "a2", "b", "c"],
"rows": 65,
"filtered": 100,
"attached_condition": "((t1.b = 'a') and (t1.c = 'i121') and (t1.a2 >= 'b'))",
"using_index_for_group_by": "scanning"
}
}
}
drop table t1;
#
# MDEV-8786 Wrong result for SELECT FORMAT=JSON * FROM t1 WHERE a=_latin1 0xDF
#
CREATE TABLE t1 (a VARCHAR(10) CHARACTER SET latin1);
INSERT INTO t1 VALUES ('a'),('b');
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE a=_latin1 0xDF;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 2,
"filtered": 100,
"attached_condition": "(t1.a = _latin1'\xDF')"
}
}
}
DROP TABLE t1;
#
# MDEV-8785 Wrong results for EXPLAIN EXTENDED...WHERE NULLIF(latin1_col, _utf8'a' COLLATE utf8_bin) IS NOT NULL
#
CREATE TABLE t1 (a VARCHAR(10) CHARACTER SET latin1);
INSERT INTO t1 VALUES ('a'),('A');
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE NULLIF(a,_utf8'a' COLLATE utf8_bin);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 2,
"filtered": 100,
"attached_condition": "(case when convert(t1.a using utf8) = <cache>((_utf8'a' collate utf8_bin)) then NULL else t1.a end)"
}
}
}
DROP TABLE t1;
#
# MDEV-7970: EXPLAIN FORMAT=JSON does not print HAVING
#
create table t0(a int);
insert into t0 values (0),(1),(2),(3);
create table t1(a int);
insert into t1 select A.a + B.a* 10 + C.a * 100 from t0 A, t0 B, t0 C;
create table t2 (
a int,
b int,
key (a)
);
insert into t2 select A.a*1000 + B.a, A.a*1000 + B.a from t0 A, t1 B;
# normal HAVING
explain format=json select a, max(b) as TOP from t2 group by a having TOP > a;
EXPLAIN
{
"query_block": {
"select_id": 1,
"having_condition": "(TOP > t2.a)",
"filesort": {
"temporary_table": {
"function": "buffer",
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 256,
"filtered": 100
}
}
}
}
}
# HAVING is always TRUE (not printed)
explain format=json select a, max(b) as TOP from t2 group by a having 1<>2;
EXPLAIN
{
"query_block": {
"select_id": 1,
"filesort": {
"temporary_table": {
"function": "buffer",
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 256,
"filtered": 100
}
}
}
}
}
# HAVING is always FALSE (intercepted by message)
explain format=json select a, max(b) as TOP from t2 group by a having 1=2;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"message": "Impossible HAVING"
}
}
}
# HAVING is absent
explain format=json select a, max(b) as TOP from t2 group by a;
EXPLAIN
{
"query_block": {
"select_id": 1,
"filesort": {
"temporary_table": {
"function": "buffer",
"table": {
"table_name": "t2",
"access_type": "ALL",
"rows": 256,
"filtered": 100
}
}
}
}
}
drop table t0, t1, t2;
#
# MDEV-8829: Assertion `0' failed in Explain_table_access::tag_to_json
#
# Check ET_CONST_ROW_NOT_FOUND
create table t1 (i int) engine=myisam;
explain
select * from t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 system NULL NULL NULL NULL 0 const row not found
explain format=json
select * from t1;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "system",
"rows": 0,
"filtered": 0,
"const_row_not_found": true
}
}
}
analyze format=json
select * from t1;
ANALYZE
{
"query_block": {
"select_id": 1,
"table": {
"message": "no matching row in const table"
}
}
}
drop table t1;
# Check ET_IMPOSSIBLE_ON_CONDITION
create table t1 (a int);
create table t2 (pk int primary key);
insert into t1 values (1),(2);
insert into t2 values (1),(2);
explain
select * from t1 left join t2 on t2.pk > 10 and t2.pk < 0;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 const PRIMARY NULL NULL NULL 1 Impossible ON condition
1 SIMPLE t1 ALL NULL NULL NULL NULL 2
explain format=json
select * from t1 left join t2 on t2.pk > 10 and t2.pk < 0;
EXPLAIN
{
"query_block": {
"select_id": 1,
"const_condition": "1",
"table": {
"table_name": "t2",
"access_type": "const",
"possible_keys": ["PRIMARY"],
"rows": 1,
"filtered": 100,
"impossible_on_condition": true
},
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 2,
"filtered": 100
}
}
}
analyze format=json
select * from t1 left join t2 on t2.pk > 10 and t2.pk < 0;
ANALYZE
{
"query_block": {
"select_id": 1,
"r_loops": 1,
"r_total_time_ms": "REPLACED",
"const_condition": "1",
"table": {
"table_name": "t2",
"access_type": "const",
"possible_keys": ["PRIMARY"],
"r_loops": 0,
"rows": 1,
"r_rows": null,
"filtered": 100,
"r_filtered": null,
"impossible_on_condition": true
},
"table": {
"table_name": "t1",
"access_type": "ALL",
"r_loops": 1,
"rows": 2,
"r_rows": 2,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100
}
}
}
# Check ET_NOT_EXISTS:
explain
select * from t1 left join t2 on t2.pk=t1.a where t2.pk is null;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2
1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1 Using where; Using index; Not exists
explain format=json
select * from t1 left join t2 on t2.pk=t1.a where t2.pk is null;
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 2,
"filtered": 100
},
"table": {
"table_name": "t2",
"access_type": "eq_ref",
"possible_keys": ["PRIMARY"],
"key": "PRIMARY",
"key_length": "4",
"used_key_parts": ["pk"],
"ref": ["test.t1.a"],
"rows": 1,
"filtered": 100,
"attached_condition": "(trigcond(isnull(t2.pk)) and trigcond(trigcond((t1.a is not null))))",
"using_index": true,
"not_exists": true
}
}
}
analyze format=json
select * from t1 left join t2 on t2.pk=t1.a where t2.pk is null;
ANALYZE
{
"query_block": {
"select_id": 1,
"r_loops": 1,
"r_total_time_ms": "REPLACED",
"table": {
"table_name": "t1",
"access_type": "ALL",
"r_loops": 1,
"rows": 2,
"r_rows": 2,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100
},
"table": {
"table_name": "t2",
"access_type": "eq_ref",
"possible_keys": ["PRIMARY"],
"key": "PRIMARY",
"key_length": "4",
"used_key_parts": ["pk"],
"ref": ["test.t1.a"],
"r_loops": 2,
"rows": 1,
"r_rows": 1,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100,
"attached_condition": "(trigcond(isnull(t2.pk)) and trigcond(trigcond((t1.a is not null))))",
"using_index": true,
"not_exists": true
}
}
}
# Check ET_DISTINCT
explain
select distinct t1.a from t1 join t2 on t2.pk=t1.a;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2 Using where; Using temporary
1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1 Using index; Distinct
explain format=json
select distinct t1.a from t1 join t2 on t2.pk=t1.a;
EXPLAIN
{
"query_block": {
"select_id": 1,
"temporary_table": {
"function": "buffer",
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 2,
"filtered": 100,
"attached_condition": "(t1.a is not null)"
},
"table": {
"table_name": "t2",
"access_type": "eq_ref",
"possible_keys": ["PRIMARY"],
"key": "PRIMARY",
"key_length": "4",
"used_key_parts": ["pk"],
"ref": ["test.t1.a"],
"rows": 1,
"filtered": 100,
"using_index": true,
"distinct": true
}
}
}
}
analyze format=json
select distinct t1.a from t1 join t2 on t2.pk=t1.a;
ANALYZE
{
"query_block": {
"select_id": 1,
"r_loops": 1,
"r_total_time_ms": "REPLACED",
"temporary_table": {
"table": {
"table_name": "t1",
"access_type": "ALL",
"r_loops": 1,
"rows": 2,
"r_rows": 2,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100,
"attached_condition": "(t1.a is not null)"
},
"table": {
"table_name": "t2",
"access_type": "eq_ref",
"possible_keys": ["PRIMARY"],
"key": "PRIMARY",
"key_length": "4",
"used_key_parts": ["pk"],
"ref": ["test.t1.a"],
"r_loops": 2,
"rows": 1,
"r_rows": 1,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100,
"using_index": true,
"distinct": true
}
}
}
}
drop table t1,t2;
# Check ET_USING_INDEX_CONDITION_BKA
create table t1(a int);
insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t2(a int);
insert into t2 select A.a + B.a* 10 + C.a * 100 from t1 A, t1 B, t1 C;
create table t3(a int, b int);
insert into t3 select a,a from t1;
create table t4(a int, b int, c int, filler char(100), key (a,b));
insert into t4 select a,a,a, 'filler-data' from t2;
set @tmp_optimizer_switch=@@optimizer_switch;
set @tmp_join_cache_level=@@join_cache_level;
set optimizer_switch='mrr=on';
set join_cache_level=6;
explain
select * from t3,t4 where t3.a=t4.a and (t4.b+1 <= t3.b+1);
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t3 ALL NULL NULL NULL NULL 10 Using where
1 SIMPLE t4 ref a a 5 test.t3.a 1 Using index condition(BKA); Using join buffer (flat, BKA join); Rowid-ordered scan
explain format=json
select * from t3,t4 where t3.a=t4.a and (t4.b+1 <= t3.b+1);
EXPLAIN
{
"query_block": {
"select_id": 1,
"table": {
"table_name": "t3",
"access_type": "ALL",
"rows": 10,
"filtered": 100,
"attached_condition": "(t3.a is not null)"
},
"block-nl-join": {
"table": {
"table_name": "t4",
"access_type": "ref",
"possible_keys": ["a"],
"key": "a",
"key_length": "5",
"used_key_parts": ["a"],
"ref": ["test.t3.a"],
"rows": 1,
"filtered": 100,
"index_condition_bka": "((t4.b + 1) <= (t3.b + 1))"
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BKA",
"mrr_type": "Rowid-ordered scan"
}
}
}
analyze format=json
select * from t3,t4 where t3.a=t4.a and (t4.b+1 <= t3.b+1);
ANALYZE
{
"query_block": {
"select_id": 1,
"r_loops": 1,
"r_total_time_ms": "REPLACED",
"table": {
"table_name": "t3",
"access_type": "ALL",
"r_loops": 1,
"rows": 10,
"r_rows": 10,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100,
"attached_condition": "(t3.a is not null)"
},
"block-nl-join": {
"table": {
"table_name": "t4",
"access_type": "ref",
"possible_keys": ["a"],
"key": "a",
"key_length": "5",
"used_key_parts": ["a"],
"ref": ["test.t3.a"],
"r_loops": 1,
"rows": 1,
"r_rows": 10,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100,
"index_condition_bka": "((t4.b + 1) <= (t3.b + 1))"
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BKA",
"mrr_type": "Rowid-ordered scan",
"r_filtered": 100
}
}
}
set optimizer_switch=@tmp_optimizer_switch;
set join_cache_level=@tmp_join_cache_level;
drop table t1,t2,t3,t4;
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