MySQL Bugs: #63994: Show status - Difference between com_update and com_update

Bug #63994	Show status - Difference between com_update and com_update_multi
Submitted:	11 Jan 2012 14:19	Modified:	26 Mar 2013 22:23
Reporter:	Mahesh Patil	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S3 (Non-critical)
Version:	5.1+	OS:	Any
Assigned to:	Paul DuBois	CPU Architecture:	Any

Description:
Execute show status like 'com_update%'
show com_update and com_update_multi values 

I want to know exact diffrence between them, Please explain?

How to repeat:
Difference between com_update and com_update_multi

Documentation also does not show any information about com_stmt and com_stmt_multi in general
http://dev.mysql.com/doc/refman/5.5/en/server-status-variables.html#statvar_Com_xxx

This is actually easy to show:

mysql> show session status like 'com_update%';
+------------------+-------+
| Variable_name    | Value |
+------------------+-------+
| Com_update       | 2     |
| Com_update_multi | 2     |
+------------------+-------+
2 rows in set (0.00 sec)

mysql> update tfr t1, tfr t2 set t1.c1 = 2;
Query OK, 0 rows affected (0.00 sec)
Rows matched: 1  Changed: 0  Warnings: 0

mysql> show session status like 'com_update%';
+------------------+-------+
| Variable_name    | Value |
+------------------+-------+
| Com_update       | 2     |
| Com_update_multi | 3     |
+------------------+-------+
2 rows in set (0.00 sec)

mysql> update tfr set c1 = 1;
Query OK, 0 rows affected (0.00 sec)
Rows matched: 1  Changed: 0  Warnings: 0

mysql> show session status like 'com_update%';
+------------------+-------+
| Variable_name    | Value |
+------------------+-------+
| Com_update       | 3     |
| Com_update_multi | 3     |
+------------------+-------+
2 rows in set (0.00 sec)

So, Com_update_multi is incremented when multiple table update syntax is used (see http://dev.mysql.com/doc/refman/5.1/en/update.html). 

But you are right - our manual should probably give some hint about this...

Thank you for your bug report. This issue has been addressed in the documentation. The updated documentation will appear on our website shortly, and will be included in the next release of the relevant products.

I worked the descriptions into the initial part of the Com_xxx text:

There is one status variable for each type of statement. For example,
Com_delete and Com_update count DELETE and UPDATE statements,
respectively. Com_delete_multi and Com_update_multi are similar but
apply to DELETE and UPDATE statements that use multiple-table syntax.