So I spent several hours over the last few days on the Secondary index bug. Out of frustration I decided to try and bypass the LRU concept all together and try going to a true secondary page cache. In standard Waffle a page is written to memcached only when it is expunged ( or LRU’d ) from the main buffer pool. This means anything in the BP should not be in memcached. Obviously with this approach we missed something, as Heikii pointed out in a comment to a previous post, it seems likely we are getting an old version of a page. Logically this could happen if we do not correctly expire a page on get or we bypass a push/lru leaving an old page in memcached to be retrieved later on.

So I was thinking why not bypass the LRU process? While I feel this is the most efficient way to do this, its not the only way. I modified innodb to use the default LRU code and then modified the page get to push to memcached on any disk read. Additionally I added …

I wrote a small DTrace script to understand InnoDB IO statistics. This script shows statistics about different kinds of Innodb IO requests and how many of them result in actual IO. Sample output is shown below

#./inniostat -h
Usage: inniostat [-h] [-d] [-p pid] [interval]
                 -h : Print this message
                 -p : MySQL PID
                 -d : Dump dtrace script being used

# ./inniostat
 __physical__  ___Innodb___ ____read____     ______write______
   r/s    w/s    r/s    w/s   data    pre    log dblbuf dflush     Time
    24    121     24     50     24      0     50      0      0 16:00:57
    26    130     26     51     26      0     51      0      0 16:00:58
    18    134     18     54     18      0     54      0      0 16:00:59
    25    129     25     51     25      0     51      0      0 16:01:00
    29    116     46     47     17     29     47      0      0 16:01:01
    10    140     10    132     10      0     52      0     80 …

I wrote a small DTrace script to understand InnoDB IO statistics. This script shows statistics about different kinds of Innodb IO requests and how many of them result in actual IO. Sample output is shown below

#./inniostat -h
Usage: inniostat [-h] [-d] [-p pid] [interval]
                 -h : Print this message
                 -p : MySQL PID
                 -d : Dump dtrace script being used

# ./inniostat
 __physical__  ___Innodb___ ____read____     ______write______
   r/s    w/s    r/s    w/s   data    pre    log dblbuf dflush     Time
    24    121     24     50     24      0     50      0      0 16:00:57
    26    130     26     51     26      0     51      0      0 16:00:58
    18    134     18     54     18      0     54      0      0 16:00:59
    25    129     25     51     25      0     51      0      0 16:01:00
    29    116     46     47     17     29     47      0      0 16:01:01
    10    140     10    132     10      0     52      0     80 …

Would you trust a 'for profit' company to represent your best interests? Perhaps. But when your interests diverge, will they represent you or themselves?

Following the overwhelming success of our first article on the domain name industry (1 comment ;-), we naturally thought you were begging for more! I know, I know registrars and registries can be a bit dull, but it is important. Believe me when something goes wrong with your domain name, understanding this can be quite important. So if we look at how and where issues can be dealt with, and who has influence in the industry it sheds a bit more light on the subject.

So now we know who's who in the tree (ICANN, Registries, Registrars, Resellers and You) we can see how the influence the landscape and who has control of what. In a nutshell:

…

Dear Lazyweb,

Yesterday I tried to Rsync a MySQL data directory from serverA to serverB on the same network. I thought that if out of a few hunded gigabytes maybe 2% changed, this should work, right? Wrong. Rsync is designed to minimize bandwidth, so in my case it was *much* quicker to wipe the data and start again (I feel this is something I should have known earlier, but it doesn't hurt to try and share your mistakes).

Which gets me thinking - it doesn't have to be this way. Bit-torrent works in a similar way to Rsync, but it's certainly not network efficient. Are there any projects similar to Rsync that are using network-hungry algorithms to try and make sure that two directories are in sync with the goal just being as fast as possible?

Dear Lazyweb,

Yesterday I tried to Rsync a MySQL data directory from serverA to serverB on the same network. I thought that if out of a few hunded gigabytes maybe 2% changed, this should work, right? Wrong. Rsync is designed to minimize bandwidth, so in my case it was *much* quicker to wipe the data and start again (I feel this is something I should have known earlier, but it doesn't hurt to try and share your mistakes).

Which gets me thinking - it doesn't have to be this way. Bit-torrent works in a similar way to Rsync, but it's certainly not network efficient. Are there any projects similar to Rsync that are using network-hungry algorithms to try and make sure that two directories are in sync with the goal just being as fast as possible?

I just realized that I haven't blogged for more than a month! Shame on me. But I will blame it on being away on conferences and vacation for quite some time And if you are following me on twitter, you may have noticed what I was going on in my life and that I did't get hit by a bus...

So what was going on since I returned back home from the MySQL Conference? First off, I uploaded und sorted my pictures from the conference and the Drizzle developer day on Flickr. I also uploaded the slides (PDF) from Colin and myself speaking about "MySQL Server Backup, …

When meeting with MySQL customers I find they usually have some very strong misperceptions of using the free version (Community Version) of MySQL and that they have no need to purchase the Enterprise Version of MySQL.First of all, most new MySQL users do not install, configure, tune or manage the MySQL database server properly. MySQL is the easiest database server in the world to install, but if

I have seen this question more than once, and I have answered it more than once, but let me get you the facts here, so you know what to look for:

First, Embedded MySQL isn't necessarily the same thing as libmysqld. Libmysqld is the technically embedded MySQL server in a library, in your application. As far as the MySQL website goes though, this is not necessarily how it works. On the website, Embedded MySQL refers to any kind of embedding of MySQL in an application, be it the "normal" MYSQL Server that has been embedded, or be it libmysqld.

This is confusing, and unnecessary, but I have failed to fix this, although I have tried, and this convention has been in place for so long now, that it is difficult to change (also, it means I can keep my job, as I have to explain this to people frequently. Not the most fun of jobs though).

For anyone wanting to …

Dear Kettle friends,

Will Gorman and Mike D’Amour, Senior Developers at Pentaho, are presenting Pentaho’s Google integration work at the Google I/O Developer Conference. (at the Sandbox area to be specific)   Yesterday, Pentaho announced that much.

Here are a few of the integration points:

• Google maps dashboard (available in the Pentaho BI server you can download)
• A new Google Docs step was created for Pentaho Data Integration Enterprise Edition
• Running (AVI, 30MB) the …