MySQL Bugs: #54909: Confusing description about read_buffer_size and read_rnd_buffer

Bug #54909	Confusing description about read_buffer_size and read_rnd_buffer_size
Submitted:	30 Jun 2010 8:21	Modified:	15 Oct 2010 13:37
Reporter:	Yoshiaki Tajika (Basic Quality Contributor)	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: General	Severity:	S3 (Non-critical)
Version:	5.1.48	OS:	Windows
Assigned to:	Georgi Kodinov	CPU Architecture:	Any
Tags:	qc

Description:
I can see the description below in my my.ini, which is a derivative
of my-template.ini packaged in mysql-essential-5.1.48-win32.msi.

> #*** MyISAM Specific options
   : (snip)
> # Size of the buffer used for doing full table scans of MyISAM tables.
> # Allocated per thread, if a full scan is needed.
> read_buffer_size=64K
> read_rnd_buffer_size=256K
> 
> # This buffer is allocated when MySQL needs to rebuild the index in
> # REPAIR, OPTIMZE, ALTER table statements as well as in LOAD DATA INFILE
> # into an empty table. It is allocated per thread so be careful with
> # large settings.
> sort_buffer_size=256K
>
> #*** INNODB Specific options ***

On the other hand, I can also see the description below 
in the reference manual at
http://dev.mysql.com/doc/refman/5.1/en/server-system-variables.html#sysvar_read_rnd_buffer...

> read_buffer_size and read_rnd_buffer_size are not specific 
> to any storage engine and apply in a general manner for optimization. 

And I could not confirm whether sort_buffer_size is storage engine specific.

Anyway, I hope that you clarify read_buffer_size, read_rnd_buffer_size,
and sort buffer_size are storage engine specific or not, and 
give users consistent description between my-template.ini and the manual.

How to repeat:
n/a.

sort_buffer_size is not storage-engine specific. I've added a note to the variable description in the manual.

I looked at the template .cnf files in the support-files directory of mysql-5.1 and mysql-trunk. It appears that the problem is specific to my-innodb-heavy-4G.cnf.sh: read_buffer_size and read_rnd_buffer_size are listed in the section of MySQL-specific variables. These entries should be in a general server settings section.

Sorry, "MySQL-specific" in the previous comment should be "MyISAM-specific".

Suggested patch for my-innodb-heavy-4G.cnf.sh

Attachment: patch.txt (text/plain), 1.52 KiB.

Slightly revised patch

Attachment: patch.txt (text/plain), 1.51 KiB.

Unassigning myself. This is no longer a docs bug.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/115190

3476 Georgi Kodinov	2010-08-06
      Bug #54909: Confusing description about read_buffer_size and
      read_rnd_buffer_size
      
      Applied the updated description from Paul's patch.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/115195

3476 Georgi Kodinov	2010-08-06
      Bug #54909: Confusing description about read_buffer_size and
      read_rnd_buffer_size
      
      Applied the updated description from Paul's patch.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/115210

3478 Georgi Kodinov	2010-08-06
      Bug #54909: Confusing description about read_buffer_size and
      read_rnd_buffer_size
      
      Applied the updated description from Paul's patch.

Pushed into mysql-trunk 5.6.1-m4 (revid:alik@sun.com-20100818071819-2lu46b0mm3cs34rf) (version source revid:alik@sun.com-20100818071732-g682fg1v0nnrrutx) (merge vers: 5.6.1-m4) (pib:20)

Pushed into mysql-next-mr (revid:alik@sun.com-20100818071923-4ounwbhiium2met1) (version source revid:alik@sun.com-20100818071743-lrzordai06i2crty) (pib:20)

Pushed into mysql-5.5 5.5.6-m3 (revid:alik@sun.com-20100818071719-dktnkvt8zvidj0sy) (version source revid:alik@sun.com-20100818071719-dktnkvt8zvidj0sy) (merge vers: 5.5.6-m3) (pib:20)

Cosmetic changes. No changelog entry needed.

Pushed into mysql-5.1 5.1.52 (revid:sunanda.menon@sun.com-20100928083322-wangbv97uobu7g66) (version source revid:sunanda.menon@sun.com-20100928083322-wangbv97uobu7g66) (merge vers: 5.1.52) (pib:21)

Pushed into mysql-5.1-telco-7.0 5.1.51-ndb-7.0.20 (revid:martin.skold@mysql.com-20101014082627-jrmy9xbfbtrebw3c) (version source revid:martin.skold@mysql.com-20101014082627-jrmy9xbfbtrebw3c) (merge vers: 5.1.51-ndb-7.0.20) (pib:21)

Pushed into mysql-5.1-telco-6.3 5.1.51-ndb-6.3.39 (revid:martin.skold@mysql.com-20101014083757-5qo48b86d69zjvzj) (version source revid:martin.skold@mysql.com-20101014083757-5qo48b86d69zjvzj) (merge vers: 5.1.51-ndb-6.3.39) (pib:21)

Pushed into mysql-5.1-telco-6.2 5.1.51-ndb-6.2.19 (revid:martin.skold@mysql.com-20101014084420-y54ecj85j5we27oa) (version source revid:martin.skold@mysql.com-20101014084420-y54ecj85j5we27oa) (merge vers: 5.1.51-ndb-6.2.19) (pib:21)

Set back to Closed -- see above.