Bug #87519 "show engine innodb status" my be not correct

• Submitted: 24 Aug 2017 2:15
• Modified: 24 Aug 2017 9:14
• Reporter: ashe sun (OCA)
• Status: Not a Bug
• Category: MySQL Server: InnoDB storage engine
• Severity: S3 (Non-critical)
• Version: mysql-5.7.19
• OS: Any
• CPU Architecture: Any

[24 Aug 2017 2:15] ashe sun

Description:
There is no update  on this server:

mysql> select @@version;
+------------+
| @@version  |
+------------+
| 5.7.19-log |
+------------+
1 row in set (0.00 sec)

mysql> flush engine logs;
Query OK, 0 rows affected (0.01 sec)

mysql> show engine innodb status\G
.....
LOG
---
Log sequence number 2593987
Log flushed up to   2593987
Pages flushed up to 2593987
Last checkpoint at  2593978
0 pending log flushes, 0 pending chkp writes
212 log i/o's done, 0.00 log i/o's/second
----------------------
......

Log sequence number  == Log flushed up to ==Pages flushed up to  != Last checkpoint at

why? what is that 9 bytes.(2593987-2593978 = 9)

on mysql-5.6.23,that four parameters are equal to each other.

How to repeat:
As Description.

[24 Aug 2017 9:00] MySQL Verification Team

Hello Ashe Sun,

Thank you for the report.
Discussed internally with Innodb developer and confirmed that this is by design and expected behavior in 5.7, MLOG_CHECKPOINT record added as a part of checkpoint. It is 9 bytes length.

Thanks,
Umesh

[24 Aug 2017 9:14] ashe sun

Hello Umesh

Thanks a lot!

I got it.