Comments on: MyISAM mmap feature (5.1) http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/ Everything about MySQL Performance Tue, 07 Oct 2008 14:27:32 +0000 http://wordpress.org/?v=2.5.1 By: domas mituzas: vaporware, inc. » Blog Archive » mmap() http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-345869 domas mituzas: vaporware, inc. » Blog Archive » mmap() Sun, 17 Aug 2008 19:52:04 +0000 http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-345869 [...] now MySQL is using mmap() just for packed MyISAM files. Vadim wrote a patch to do more of [...] [...] now MySQL is using mmap() just for packed MyISAM files. Vadim wrote a patch to do more of [...]

]]> By: Michael http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-265255 Michael Thu, 03 Apr 2008 21:35:53 +0000 http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-265255 As this article is several years old, would it be possible to post the 5.0 series patch if it will still apply to the current 5.0.54 (or other) release? Thanks, Michael As this article is several years old, would it be possible to post the 5.0 series patch if it will still apply to the current 5.0.54 (or other) release?

Thanks,
Michael

]]> By: Yuri http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-1951 Yuri Tue, 22 Aug 2006 15:37:16 +0000 http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-1951 Great, thank you! I've got about 10-15% performance on SELECTs with multiple simple joins using unindexes LIKE and REGEXP searches throught a table with 1m records. Great, thank you! I’ve got about 10-15% performance on SELECTs with multiple simple joins
using unindexes LIKE and REGEXP searches throught a table with 1m records.

]]> By: Vadim http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-1090 Vadim Wed, 19 Jul 2006 07:10:42 +0000 http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-1090 Valeriy, I don't think mmap require changes in ulimit -n. At least I have not heard about. Regarding that bug it could be out of memory error on 32bit. Maybe there is still restriction in 2GB summary for allocated memory and mmaped size. I'll try to investigate this. Valeriy,

I don’t think mmap require changes in ulimit -n. At least I have not heard about.

Regarding that bug it could be out of memory error on 32bit.
Maybe there is still restriction in 2GB summary for allocated memory and mmaped size.
I’ll try to investigate this.

]]> By: Valeriy Kravchuk http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-808 Valeriy Kravchuk Tue, 04 Jul 2006 14:47:16 +0000 http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-808 Vadim, Does --myisam_use_mmap=1 require any changes in ulimit -n settings? It is about MySQL bug #19800... Vadim,

Does –myisam_use_mmap=1 require any changes in ulimit -n settings? It is about MySQL bug #19800…

]]> By: Vadim http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-169 Vadim Thu, 15 Jun 2006 07:39:59 +0000 http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-169 Kevin, Heh, I also don't know how to get cache hit rate. Some statistics is available in /proc/slabinfo (http://seth.positivism.org/man.cgi/5/slabinfo) but there is no hit statistics Kevin,

Heh, I also don’t know how to get cache hit rate.
Some statistics is available in /proc/slabinfo (http://seth.positivism.org/man.cgi/5/slabinfo) but there is no hit statistics

]]> By: Kevin Burton http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-168 Kevin Burton Thu, 15 Jun 2006 06:32:10 +0000 http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-168 One thing that bothers me is that I'm not able to determine my OS cache efficiency. I use munin and RRD to graph as many stats about MySQL as possible. Number of slow queries, query cache efficiency, etc. The problem is I can't figure out where Linux keeps stats on its file cache hit rate. Anyone have any idea? email me please and I'll write a munin plugin for it :) Kevin One thing that bothers me is that I’m not able to determine my OS cache efficiency.

I use munin and RRD to graph as many stats about MySQL as possible. Number of slow queries, query cache efficiency, etc.

The problem is I can’t figure out where Linux keeps stats on its file cache hit rate.

Anyone have any idea? email me please and I’ll write a munin plugin for it :)

Kevin

]]> By: Vadim http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-49 Vadim Fri, 26 May 2006 12:57:04 +0000 http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-49 Not so hard, I even have a patch for 5.0 tree, but MySQL policy does not allow to include new features into GA trees. Not so hard, I even have a patch for 5.0 tree, but MySQL policy does not allow to include new features into GA trees.

]]> By: stanojr http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-47 stanojr Fri, 26 May 2006 12:19:50 +0000 http://www.mysqlperformanceblog.com/2006/05/26/myisam-mmap-feature-51/#comment-47 uuu, that is cool it will be hard to backport this feature to old versions of mysql ? uuu, that is cool
it will be hard to backport this feature to old versions of mysql ?

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