Example verification MySQL | update field with the same value will record binlog

1. Introduction

A few days ago, a development colleague asked me whether updating a field to the same value would record binlog. I replied that it would not.

Strictly speaking, this answer is inaccurate, as it is necessary to distinguish between scenarios. Whether to record update statements in binlog depends on the setting of binlog_format. Practice makes perfect in specific situations.

Second test

2.1 binlog_format is ROW mode

2.2 binlog_format is in STATEMENT mode

Parse the binlog content and record the update statement completely.

2.2 binlog_format is in MIXED mode

When row_format is mixed or statement format, the size of the binlog changes. Regardless of whether the data is actually updated, MySQL records the executed SQL to the binlog.

Three conclusions

In row-based mode, the server layer matches the record to be updated and finds that the new value is consistent with the old value. It does not update the record and returns directly without recording the binlog.

Based on the statement or mixed format, MySQL executes the update statement and records the update statement to the binlog.

So why do statement and mixed record the complete SQL statement? I will explain this in the next article, because I need to parse the source code and have not yet succeeded in compiling the MySQL debugging environment using Clion.

The above is an example to verify whether the MySQL|update field will record the details of the binlog when it has the same value. For more information about the MySQL update field, please pay attention to other related articles on 123WORDPRESS.COM!