MySQL Bugs: #117286: A example in transaction isolation levels part is not accurate

Bug #117286	A example in transaction isolation levels part is not accurate
Submitted:	24 Jan 2025 3:11	Modified:	24 Jan 2025 11:47
Reporter:	Rungong An	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S3 (Non-critical)
Version:	8.0	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
The example in "https://dev.mysql.com/doc/refman/9.2/en/innodb-transaction-isolation-levels.html" (and other versions) as below is not accurate:

```
For the second UPDATE, InnoDB does a “semi-consistent” read, returning the latest committed version of each row that it reads to MySQL so that MySQL can determine whether the row matches the WHERE condition of the UPDATE:

x-lock(1,2); update(1,2) to (1,4); retain x-lock
x-lock(2,3); unlock(2,3)
x-lock(3,2); update(3,2) to (3,4); retain x-lock
x-lock(4,3); unlock(4,3)
x-lock(5,2); update(5,2) to (5,4); retain x-lock

```

This may be better:

```
For the second UPDATE, InnoDB does a “semi-consistent” read, returning the latest committed version of each row that it reads to MySQL so that MySQL can determine whether the row matches the WHERE condition of the UPDATE:

x-lock(1,2); update(1,2) to (1,4); retain x-lock
semi-consistent read(2,3) when (2,3) is x-locked;
x-lock(3,2); update(3,2) to (3,4); retain x-lock
semi-consistent read(4,3) when (4,3) is x-locked;
x-lock(5,2); update(5,2) to (5,4); retain x-lock

```

How to repeat:
document improvement

Hi Mr. Rungong,

Thank you for your bug report.

We agree with you.

This is now a verified documentation bug for the version 8.0 and higher.