drop table if exists t0, t1, t2, t3, t4;
drop view if exists v1; SET @old_debug= @@session.debug_dbug; set debug_sync='RESET';
create table t0 (a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1 (a int);
alter table t1 add b int, add c int, add filler char(32);
insert into t1 select A.a, 10*B.a, 100*C.a, 'foo filler' from t0 A, t0 B, t0 C;
alter table t1 add key(a), add key(b);
analyze table t1;
Table Op Msg_type Msg_text
test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status Table is already up to date
show analyze for 1001; ERROR HY000: Unknown thread id: 1001
show analyze for (select a from t0 limit 1); ERROR HY000: You may only use constant expressions in this statement
connect con1, localhost, root,,;
connection con1; SET @old_debug= @@session.debug_dbug;
connection default;
show analyze for $thr2; ERROR HY000: Target is not executing an operation with a query plan
show analyze for $thr1; ERROR HY000: Target is not executing an operation with a query plan
connection con1; set @show_explain_probe_select_id=1; SET debug_dbug='+d,show_explain_probe_join_exec_end';
select count(*) from t1 where c < 500;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 10001000.0050.0050.00 Using where
Warnings:
Note 1003 select count(*) from t1 where c < 500
connection con1;
count(*) 500
select max(c) from t1 where c < 10;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 10001000.0010.0010.00 Using where
Warnings:
Note 1003 select max(c) from t1 where c < 10
connection con1; max(c) 0
# We can catch ANALYZE too.
analyze select max(c) from t1 where a < 10;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 SIMPLE t1 ALL a NULL NULL NULL 10001000.0099.90100.00 Using where
Warnings:
Note 1003 analyze select max(c) from t1 where a < 10
connection con1;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 SIMPLE t1 ALL a NULL NULL NULL 10001000.0099.90100.00 Using where SET debug_dbug=@old_debug;
# UNION, select, first branch set @show_explain_probe_select_id=1; SET debug_dbug='+d,show_explain_probe_join_exec_end';
select max(a) from t0 A where a<=5 union select max(a+1) from t0 B where a>=9;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY A ALL NULL NULL NULL NULL 1010.00100.0060.00 Using where 2 UNION B ALL NULL NULL NULL NULL 10 NULL 100.00 NULL Using where
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL 0.00 NULL NULL
Warnings:
Note 1003 select max(a) from t0 A where a<=5 union select max(a+1) from t0 B where a>=9
connection con1; max(a) 5 10
# UNION, select, second branch set @show_explain_probe_select_id=2; SET debug_dbug='+d,show_explain_probe_join_exec_end';
select max(a) from t0 A where a<=5 union select max(a+1) from t0 B where a>=9;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY A ALL NULL NULL NULL NULL 1010.00100.0060.00 Using where 2 UNION B ALL NULL NULL NULL NULL 1010.00100.0010.00 Using where
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL 0.00 NULL NULL
Warnings:
Note 1003 select max(a) from t0 A where a<=5 union select max(a+1) from t0 B where a>=9
connection con1; max(a) 5 10
# UNION, analyze, first branch set @show_explain_probe_select_id=1; SET debug_dbug='+d,show_explain_probe_join_exec_end';
analyze select a from t0 A where a<=5 union select a+1 from t0 B where a>=9;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY A ALL NULL NULL NULL NULL 1010.00100.0060.00 Using where 2 UNION B ALL NULL NULL NULL NULL 10 NULL 100.00 NULL Using where
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL 0.00 NULL NULL
Warnings:
Note 1003 analyze select a from t0 A where a<=5 union select a+1 from t0 B where a>=9
connection con1;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY A ALL NULL NULL NULL NULL 1010.00100.0060.00 Using where 2 UNION B ALL NULL NULL NULL NULL 1010.00100.0010.00 Using where
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL 7.00 NULL NULL
# UNION, analyze, second branch set @show_explain_probe_select_id=2;
analyze select a from t0 A where a<=5 union select a+1 from t0 B where a>=9;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY A ALL NULL NULL NULL NULL 1010.00100.0060.00 Using where 2 UNION B ALL NULL NULL NULL NULL 1010.00100.0010.00 Using where
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL 0.00 NULL NULL
Warnings:
Note 1003 analyze select a from t0 A where a<=5 union select a+1 from t0 B where a>=9
connection con1;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY A ALL NULL NULL NULL NULL 1010.00100.0060.00 Using where 2 UNION B ALL NULL NULL NULL NULL 1010.00100.0010.00 Using where
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL 7.00 NULL NULL SET debug_dbug=@old_debug;
# Uncorrelated subquery, select set @show_explain_probe_select_id=1; SET debug_dbug='+d,show_explain_probe_join_exec_end';
select a, (select max(a) from t0 B where a>6) from t0 A where a<2;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY A ALL NULL NULL NULL NULL 1010.00100.0020.00 Using where 2 SUBQUERY B ALL NULL NULL NULL NULL 1010.00100.0030.00 Using where
Warnings:
Note 1003 select a, (select max(a) from t0 B where a>6) from t0 A where a<2
connection con1;
a (select max(a) from t0 B where a>6) 09 19 SET debug_dbug=@old_debug;
# Uncorrelated subquery, analyze set @show_explain_probe_select_id=1; SET debug_dbug='+d,show_explain_probe_join_exec_end';
analyze select a, (select max(a) from t0 B where a>6) from t0 A where a<2;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY A ALL NULL NULL NULL NULL 1010.00100.0020.00 Using where 2 SUBQUERY B ALL NULL NULL NULL NULL 1010.00100.0030.00 Using where
Warnings:
Note 1003 analyze select a, (select max(a) from t0 B where a>6) from t0 A where a<2
connection con1;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY A ALL NULL NULL NULL NULL 1010.00100.0020.00 Using where 2 SUBQUERY B ALL NULL NULL NULL NULL 1010.00100.0030.00 Using where SET debug_dbug=@old_debug;
# correlated subquery, select, before execution start set @show_explain_probe_select_id=1; SET debug_dbug='+d,show_explain_probe_join_exec_start';
select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<2;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY a ALL NULL NULL NULL NULL 10 NULL 100.00 NULL Using where 2 DEPENDENT SUBQUERY b ALL NULL NULL NULL NULL 10 NULL 100.00 NULL Using where
Warnings:
Note 1003 select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<2
connection con1;
a (select max(a) from t0 b where b.a+a.a<10) 09 18 SET debug_dbug=@old_debug;
# correlated subquery, select, after execution set @show_explain_probe_select_id=1; SET debug_dbug='+d,show_explain_probe_join_exec_end';
select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<2;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY a ALL NULL NULL NULL NULL 1010.00100.0020.00 Using where 2 DEPENDENT SUBQUERY b ALL NULL NULL NULL NULL 1010.00100.0095.00 Using where
Warnings:
Note 1003 select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<2
connection con1;
a (select max(a) from t0 b where b.a+a.a<10) 09 18 SET debug_dbug=@old_debug;
# correlated subquery, analyze set @show_explain_probe_select_id=1; SET debug_dbug='+d,show_explain_probe_join_exec_end';
analyze select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<2;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY a ALL NULL NULL NULL NULL 1010.00100.0020.00 Using where 2 DEPENDENT SUBQUERY b ALL NULL NULL NULL NULL 1010.00100.0095.00 Using where
Warnings:
Note 1003 analyze select a, (select max(a) from t0 b where b.a+a.a<10) from t0 a where a<2
connection con1;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY a ALL NULL NULL NULL NULL 1010.00100.0020.00 Using where 2 DEPENDENT SUBQUERY b ALL NULL NULL NULL NULL 1010.00100.0095.00 Using where SET debug_dbug=@old_debug;
# Try to do SHOW ANALYZE for a query that runs a SET command:
#
create table t2 (a int);
insert into t2 values (1),(2); set @show_explain_probe_select_id=3; SET debug_dbug='+d,show_explain_probe_join_exec_start'; set @foo= (select max(a) from t2
where a + (select max(a) from t0 where t0.a>t2.a) < 10000);
connection default;
show analyze for $thr2; ERROR HY000: Target is not executing an operation with a query plan
kill query $thr2;
connection con1; ERROR70100: Query execution was interrupted SET debug_dbug=@old_debug;
drop table t2;
#
# Attempt SHOW ANALYZE for an UPDATE
#
create table t2 as select a as a, a as dummy from t0 limit 2; set @show_explain_probe_select_id=2; SET debug_dbug='+d,show_explain_probe_join_exec_start';
update t2 set dummy=0 where (select max(a) from t0 where t2.a + t0.a <3) >3;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 21.00100.000.00 Using where 2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 10 NULL 100.00 NULL Using where
Warnings:
Note 1003 update t2 set dummy=0 where (select max(a) from t0 where t2.a + t0.a <3) >3
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 22.00100.000.00 Using where 2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 1010.00100.0030.00 Using where
Warnings:
Note 1003 update t2 set dummy=0 where (select max(a) from t0 where t2.a + t0.a <3) >3
connection con1;
drop table t2; SET debug_dbug=@old_debug;
#
# Attempt SHOW ANALYZE for a DELETE
#
create table t2 as select a as a, a as dummy from t0 limit 2; set @show_explain_probe_select_id=2; SET debug_dbug='+d,show_explain_probe_join_exec_start';
delete from t2 where (select max(a) from t0 where t2.a + t0.a <3) >3;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 21.00100.000.00 Using where 2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 10 NULL 100.00 NULL Using where
Warnings:
Note 1003 delete from t2 where (select max(a) from t0 where t2.a + t0.a <3) >3
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 22.00100.000.00 Using where 2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 1010.00100.0030.00 Using where
Warnings:
Note 1003 delete from t2 where (select max(a) from t0 where t2.a + t0.a <3) >3
connection con1;
drop table t2; SET debug_dbug=@old_debug;
#
# Multiple SHOW ANALYZE calls for one select
#
create table t2 as select a as a, a as dummy from t0 limit 3; set @show_explain_probe_select_id=2; SET debug_dbug='+d,show_explain_probe_join_exec_start';
select t2.a, ((select max(a) from t0 where t2.a + t0.a <3) >3) as SUBQ from t2;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 31.00100.00100.00 2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 10 NULL 100.00 NULL Using where
Warnings:
Note 1003 select t2.a, ((select max(a) from t0 where t2.a + t0.a <3) >3) as SUBQ from t2
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 32.00100.00100.00 2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 1010.00100.0030.00 Using where
Warnings:
Note 1003 select t2.a, ((select max(a) from t0 where t2.a + t0.a <3) >3) as SUBQ from t2
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 33.00100.00100.00 2 DEPENDENT SUBQUERY t0 ALL NULL NULL NULL NULL 1010.00100.0025.00 Using where
Warnings:
Note 1003 select t2.a, ((select max(a) from t0 where t2.a + t0.a <3) >3) as SUBQ from t2
connection con1;
a SUBQ 00 10 20 SET debug_dbug=@old_debug;
drop table t2;
#
# SHOW ANALYZE for SELECT ... ORDER BY with "Using filesort"
# SET debug_dbug='+d,show_explain_probe_join_exec_end'; set @show_explain_probe_select_id=1;
select * from t0 order by a;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 1010.00100.00100.00 Using filesort
Warnings:
Note 1003 select * from t0 order by a
connection con1;
a 0 1 2 3 4 5 6 7 8 9 SET debug_dbug=@old_debug;
#
# SHOW ANALYZE for SELECT ... with "Using temporary"
#
connection con1; SET debug_dbug='+d,show_explain_probe_join_exec_end'; set @show_explain_probe_select_id=1;
select distinct a from t0;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 1010.00100.00100.00 Using temporary
Warnings:
Note 1003 select distinct a from t0
connection con1;
a 0 1 2 3 4 5 6 7 8 9 SET debug_dbug=@old_debug;
#
# SHOW ANALYZE for SELECT ... with "Using temporary; Using filesort"
# SET debug_dbug='+d,show_explain_probe_join_exec_end'; set @show_explain_probe_select_id=1;
select distinct a from t0;
connection default;
show analyze for $thr2;
id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 1010.00100.00100.00 Using temporary
Warnings:
Note 1003 select distinct a from t0
connection con1;
a 0 1 2 3 4 5 6 7 8 9 SET debug_dbug=@old_debug;
drop table t0,t1;
#
# MDEV-28124: Server crashes in Explain_aggr_filesort::print_json_members
# upon SHOW ANALYZE/EXPLAIN FORMAT=JSON
#
connection con1; set @show_explain_probe_query= 'SELECT count(*) - count(*) FROM sys.waits_by_user_by_latency'; set debug_dbug='+d,explain_notify_tables_are_closed';
SELECT count(*) - count(*) FROM sys.waits_by_user_by_latency;
connection default;
SHOW ANALYZE FOR $thr2; ERROR HY000: Target is not executing an operation with a query plan
connection con1;
count(*) - count(*) 0
# End
connection default;
disconnect con1; set debug_sync='RESET';
#
# MDEV-28201: Server crashes upon SHOW ANALYZE/EXPLAIN FORMAT=JSON
#
CREATE TABLE t1 ( a varchar(1));
INSERT INTO t1 VALUES ('a'),('b');
ANALYZE format=json
SELECT 1 FROM t1 GROUP BY convert_tz('1969-12-31 22:00:00',a,'+10:00');
ANALYZE
{ "query_optimization": { "r_total_time_ms": "REPLACED"
}, "query_block": { "select_id": 1, "cost": "REPLACED", "r_loops": 1, "r_total_time_ms": "REPLACED", "filesort": { "sort_key": "convert_tz('1969-12-31 22:00:00',t1.a,'+10:00')", "r_loops": 1, "r_total_time_ms": "REPLACED", "r_used_priority_queue": false, "r_output_rows": 1, "r_buffer_size": "REPLACED", "r_sort_mode": "sort_key,rowid", "temporary_table": { "nested_loop": [
{ "table": { "table_name": "t1", "access_type": "ALL", "loops": 1, "r_loops": 1, "rows": 2, "r_rows": 2, "cost": "REPLACED", "r_table_time_ms": "REPLACED", "r_other_time_ms": "REPLACED", "r_engine_stats": REPLACED, "filtered": 100, "r_total_filtered": 100, "r_filtered": 100
}
}
]
}
}
}
}
DROP TABLE t1;
#
# MDEV-31432 tmp_table field accessed after free
# testing for the above (MDEV-28201) caused use after free error
#
create table t1 (x int) engine=myisam;
insert into t1 values(1); set @tmp=@@optimizer_trace; set @@optimizer_trace=1;
SELECT 1 IN
((
SELECT 1 IN (SELECT 1 AS x0
FROM
(
SELECT *
FROM (SELECT 1 AS x) AS x5
GROUP BY x,x
HAVING
x IN (
SELECT *
FROM t1 AS x1
WHERE
x IN (SELECT 1 AS x
FROM t1 AS x3
GROUP BY x
HAVING
x IN (SELECT 0 FROM t1 AS x4)
)
)
) AS x6
)
FROM
t1
)) as VAL;
VAL 0 set optimizer_trace=@tmp;
drop table t1;
Messung V0.5 in Prozent
¤ Dauer der Verarbeitung: 0.12 Sekunden
(vorverarbeitet am 2026-10-08)
¤
Die Informationen auf dieser Webseite wurden
nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit,
noch Qualität der bereit gestellten Informationen zugesichert.
Bemerkung:
Die farbliche Syntaxdarstellung und die Messung sind noch experimentell.