database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-08-01 03:47:19 +03:00
Code Activity

Fixed randomly failing test main.order_by_optimizer_innodb

Browse Source 
The problem was that sometimes InnoDB returned sligtly wrong record count
for table, which causes the optimizer to disregard the result from
the range optimizer. The end result was that the optimizer choosed a
ref access instead of a range access which caused errors in buildbot.

Fixed by adding more rows to the table to ensure that table scan is
more costly than range scan of the given interval.
This commit is contained in:
Monty
2023-10-06 18:18:37 +03:00
parent 6e9b421f77
commit 424a7a2620
2 changed files with 13 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
mysql-test/main/order_by_optimizer_innodb.result
View File

@ -2,10 +2,6 @@ drop table if exists t0,t1,t2,t3;
#
# MDEV-6402: Optimizer doesn't choose best execution plan when composite key is used
#
create table t0(a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
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 (
pk1 int(11) NOT NULL,
pk2 int(11) NOT NULL,
@ -17,13 +13,13 @@ UNIQUE KEY ux_pk1_fd5 (pk1,fd5)
) ENGINE=InnoDB;
insert into t2
select
round(log(2,t1.a+1)),
t1.a,
t1.a,
round(log(2,seq+1)),
seq,
seq,
REPEAT('filler-data-', 10),
REPEAT('filler-data-', 10)
from
t1;
seq_0_to_1999;
select pk1, count(*) from t2 group by pk1;
pk1 count(*)
0 1
@ -36,7 +32,8 @@ pk1 count(*)
7 91
8 181
9 362
10 276
10 724
11 552
# The following should use range(ux_pk1_fd5), two key parts (key_len=5+8=13)
EXPLAIN SELECT * FROM t2 USE INDEX(ux_pk1_fd5) WHERE pk1=9 AND fd5 < 500 ORDER BY fd5 DESC LIMIT 10;
id select_type table type possible_keys key key_len ref rows Extra
@ -45,7 +42,7 @@ id select_type table type possible_keys key key_len ref rows Extra
EXPLAIN SELECT * FROM t2 WHERE pk1=9 AND fd5 < 500 ORDER BY fd5 DESC LIMIT 10;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 range PRIMARY,ux_pk1_fd5 ux_pk1_fd5 13 NULL 138 Using where
drop table t0,t1, t2;
drop table t2;
#
# MDEV-6814: Server crashes in calculate_key_len on query with ORDER BY
#