bug: Query result set error，Involving primary key

[shangyanwen]

Have you read the Contributing Guidelines on issues?

• I have read the Contributing Guidelines on issues.

Please confirm if bug report does NOT exists already ?

• I confirm there is no existing issue for this

Describe the problem

mysql> SELECT count(id) FROM t1 where id<1000;
+-----------+
| count(id) |
+-----------+
|       999 |
+-----------+

Expected behavior

MySQL(innodb) results:

mysql> SELECT count(id) FROM t1 where id<1000;
+-----------+
| count(id) |
+-----------+
|       992 |
+-----------+

How To Reproduce

CREATE TABLE t1 (id BIGINT NOT NULL PRIMARY KEY auto_increment, pad1 BLOB, pad2 BLOB, pad3 BLOB, int_col INT NOT NULL DEFAULT 0);

INSERT INTO t1 SELECT NULL, RANDOM_BYTES(1024), RANDOM_BYTES(1024), RANDOM_BYTES(1024), 0 FROM dual;
INSERT INTO t1 SELECT NULL, RANDOM_BYTES(1024), RANDOM_BYTES(1024), RANDOM_BYTES(1024), 0 FROM t1 a JOIN t1 b JOIN t1 c;
INSERT INTO t1 SELECT NULL, RANDOM_BYTES(1024), RANDOM_BYTES(1024), RANDOM_BYTES(1024), 0 FROM t1 a JOIN t1 b JOIN t1 c;
INSERT INTO t1 SELECT NULL, RANDOM_BYTES(1024), RANDOM_BYTES(1024), RANDOM_BYTES(1024), 0 FROM t1 a JOIN t1 b JOIN t1 c;
SELECT count(id) FROM t1 where id<1000;

Environment

root@ub01:/stonedb57/install/bin# ./mysql --version
./mysql  Ver 14.14 Distrib 5.7.36-StoneDB, for Linux (x86_64) using  EditLine wrapper

#notes:v1.0.1

Are you interested in submitting a PR to solve the problem?

• Yes, I will!

[adofsauron]

ACK

[adofsauron]

Compare INNODB query results:

INNODB:

mysql> SELECT id FROM t1 where id < 1000 limit 20;
+----+
| id |
+----+
|  1 |
|  2 |
|  3 |
|  4 |
|  5 |
|  6 |
|  7 |
|  8 |
|  9 |
| 10 |
| 18 |
| 19 |
| 20 |
| 21 |
| 22 |
| 23 |
| 24 |
| 25 |
| 26 |
| 27 |
+----+
20 rows in set (0.00 sec)

tianmu:

mysql> SELECT id FROM t1 where id < 1000 limit 20;
+----+
| id |
+----+
|  1 |
|  2 |
|  3 |
|  4 |
|  5 |
|  6 |
|  7 |
|  8 |
|  9 |
| 10 |
| 11 |
| 12 |
| 13 |
| 14 |
| 15 |
| 16 |
| 17 |
| 18 |
| 19 |
| 20 |
+----+
20 rows in set (0.00 sec)

[adofsauron]

The reason is that mysql has an incremental lock policy, which is innodb_autoinc_lock_mode

ref: https://dev.mysql.com/doc/refman/5.7/en/innodb-auto-increment-handling.html

When innodb_autoinc_lock_mode is set to 0, INNODB autoincrement is increased to 1, the same result as TIANMU

mysql> set global innodb_autoinc_lock_mode=0;
ERROR 1238 (HY000): Variable 'innodb_autoinc_lock_mode' is a read only variable
mysql> show global variables like 'innodb_autoinc_lock_mode';
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id:    2
Current database: d51

+--------------------------+-------+
| Variable_name            | Value |
+--------------------------+-------+
| innodb_autoinc_lock_mode | 0     |
+--------------------------+-------+
1 row in set (0.01 sec)

mysql> 
mysql> 
mysql> drop table t1;
Query OK, 0 rows affected (0.01 sec)

mysql> CREATE TABLE t1 (id BIGINT NOT NULL PRIMARY KEY auto_increment, pad1 BLOB, pad2 BLOB, pad3 BLOB, int_col INT NOT NULL DEFAULT 0) ENGINE=INNODB AUTO_INCREMENT=1;
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO t1 SELECT NULL, 'abcd', 'abcd', 'abcd', 0 FROM dual;
 NULL, 'abcd', 'abcd', 'abcd', 0 FROM t1 a JOIN t1 b JOIN t1 c;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t1 SELECT NULL, 'abcd', 'abcd', 'abcd', 0 FROM t1 a JOIN t1 b JOIN t1 c;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t1 SELECT NULL, 'abcd', 'abcd', 'abcd', 0 FROM t1 a JOIN t1 b JOIN t1 c;
Query OK, 8 rows affected (0.01 sec)
Records: 8  Duplicates: 0  Warnings: 0

mysql> INSERT INTO t1 SELECT NULL, 'abcd', 'abcd', 'abcd', 0 FROM t1 a JOIN t1 b JOIN t1 c;
Query OK, 1000 rows affected (0.00 sec)
Records: 1000  Duplicates: 0  Warnings: 0

mysql> SELECT id FROM t1 where id<1000 limit 20;
+----+
| id |
+----+
|  1 |
|  2 |
|  3 |
|  4 |
|  5 |
|  6 |
|  7 |
|  8 |
|  9 |
| 10 |
| 11 |
| 12 |
| 13 |
| 14 |
| 15 |
| 16 |
| 17 |
| 18 |
| 19 |
| 20 |
+----+
20 rows in set (0.00 sec)

mysql> SELECT count(id) FROM t1 where id<1000;
+-----------+
| count(id) |
+-----------+
|       999 |
+-----------+
1 row in set (0.00 sec)

mysql> show create table t1\G
*************************** 1. row ***************************
       Table: t1
Create Table: CREATE TABLE `t1` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `pad1` blob,
  `pad2` blob,
  `pad3` blob,
  `int_col` int(11) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1011 DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

[adofsauron]

This is a BUG in the testing process and will not be resolved

[RingsC]

We close it now, and feel free to reopen.