Blog | rml

struct __packed s { … }This attribute tells GCC that a type or variable should be packed into memory, using the minimum amount of space possible, potentially disregarding alignment requirements. If specified on a struct or union, all variables therein are so packed. If specified on just a specific variable, only that type is packed. As an example, a structure with a char followed by an int would most likely find the integer aligned to a memory address not immediately following the char (say, three bytes later). The compiler does this by inserting three bytes of unused packing between the two variables. A packed structure lacks this packing, potentially consuming less memory but failing to meet architecture alignment requirements.

It should also be noted that non aligned data access on some architectures (e.g. ppc) can totally cripple performance. We’re …

Blog | rml talks about a bunch of useful GCC extensions.

We generally don’t use this within mysql code. Due (no doubt) to portability issues. Maybe we should look closer at it these days. I wonder if we’d get any noticable improvement in NDB by adding it to our ndbrequire/ndbassert and CRASH_INSERTION tests. In some areas of code we do have a number of asserts.

The place to play is ndb/src/kernel/vm/pc.hpp

as actually triggering a ndbassert or ndbrequire is something that should never happen, unlikely() is a good thing to put there.

Interestingly enough, this is probably the place we also want to play with for dtrace. either that or with EXECUTE_DIRECT (and another place that Mikael mentioned on IRC last night.

My next task is to get qemu network interface working so i can get …

The call for papers for the 2006 MySQL Users‘ Conference is open. I‘m chairing the “Java” track, and am appealing to all of you users out there with a MySQL and Java story that you‘d be willing to share to submit a case study talk (or a technical talk).

I know there‘s interesting stuff out there that others would like to hear about. I‘ve heard of folks with 10‘s of thousands of transactions/second in the mailing lists, I know weather.com runs Tomcat and MySQL, Feedburner runs Tomcat and MySQL and serves up huge volumes of RSS feeds with very few machines, etc, etc. I‘d love to be able to hear about some of these folks‘ experiences (and I imagine you would too!), so if you know anybody that is interested in presenting on this kind of stuff, let them know about the CFP - http://www.mysqluc.com/cs/mysqluc2006/create/e_sess/

The call for papers for the 2006 MySQL Users' Conference is open. I'm chairing the "Java" track, and am appealing to all of you users out there with a MySQL and Java story that you'd be willing to share to submit a case study talk (or a technical talk).

I know there's interesting stuff out there that others would like to hear about. I've heard of folks with 10's of thousands of transactions/second in the mailing lists, I know weather.com runs Tomcat and MySQL, Feedburner runs Tomcat and MySQL and serves up huge volumes of RSS feeds with very few machines, etc, etc. I'd love to be able to hear about some of these folks' experiences (and I imagine you would too!), so if you know anybody that is interested in presenting on this kind of stuff, let them know about the CFP - http://www.mysqluc.com/cs/mysqluc2006/create/e_sess/

The call for papers for the 2006 MySQL Users‘ Conference is open. I‘m chairing the “Java” track, and am appealing to all of you users out there with a MySQL and Java story that you‘d be willing to share to submit a case study talk (or a technical talk).

I know there‘s interesting stuff out there that others would like to hear about. I‘ve heard of folks with 10‘s of thousands of transactions/second in the mailing lists, I know weather.com runs Tomcat and MySQL, Feedburner runs Tomcat and MySQL and serves up huge volumes of RSS feeds with very few machines, etc, etc. I‘d love to be able to hear about some of these folks‘ experiences (and I imagine you would too!), so if you know anybody that is interested in presenting on this kind of stuff, let them know about the CFP - http://www.mysqluc.com/cs/mysqluc2006/create/e_sess/

We‘re changing the version number on all connectivity libraries at MySQL (ODBC, ADO.Net, JDBC) to match the latest version of the server they work with, so the “next“ version of Connector/J will be 5.0.0.

5.0.0 should be released in the next week or so, but if you want to try out XA (the major new feature that it includes), head on over to http://downloads.mysql.com/snapshots.php#connector-j

The 5.0.x series of Connector/J is really the latest 3.1 with XA and support for server-side cursor-based row fetching backported into it, so it should progress to “stable“ quite quickly.

Connector/J 5.0 also has a neat feature in that you can integrate it with Connector/MXJ (the JMX and/or POJO object wrapper for MySQL server) as simply as putting the .jar for Connector/MXJ and the .jar for the JDBC driver in your classpath, and using “jdbc:mysql:mxj://“ for your URL prefix. That feature, in combination with the …

We're changing the version number on all connectivity libraries at MySQL (ODBC, ADO.Net, JDBC) to match the latest version of the server they work with, so the "next" version of Connector/J will be 5.0.0.

5.0.0 should be released in the next week or so, but if you want to try out XA (the major new feature that it includes), head on over to http://downloads.mysql.com/snapshots.php#connector-j

The 5.0.x series of Connector/J is really the latest 3.1 with XA and support for server-side cursor-based row fetching backported into it, so it should progress to "stable" quite quickly.

Connector/J 5.0 also has a neat feature in that you can integrate it with Connector/MXJ (the JMX and/or POJO object wrapper for MySQL server) as simply as putting the .jar for Connector/MXJ and the .jar for the JDBC driver in your classpath, and using "jdbc:mysql:mxj://" for your URL prefix. That feature, in combination with the …

We‘re changing the version number on all connectivity libraries at MySQL (ODBC, ADO.Net, JDBC) to match the latest version of the server they work with, so the “next“ version of Connector/J will be 5.0.0.

5.0.0 should be released in the next week or so, but if you want to try out XA (the major new feature that it includes), head on over to http://downloads.mysql.com/snapshots.php#connector-j

The 5.0.x series of Connector/J is really the latest 3.1 with XA and support for server-side cursor-based row fetching backported into it, so it should progress to “stable“ quite quickly.

Connector/J 5.0 also has a neat feature in that you can integrate it with Connector/MXJ (the JMX and/or POJO object wrapper for MySQL server) as simply as putting the .jar for Connector/MXJ and the .jar for the JDBC driver in your classpath, and using “jdbc:mysql:mxj://“ for your URL prefix. That feature, in combination with the …

This guide will show you how to upgrade to MySQL 5.0 on a Linux Box.

Also see MySQL 5.0 article.

Stored Procedures are a useful -but much abused- feature. Why abused? Well, sometimes it just doesn't make any sense to put certain functionality into the database server.

A key positive is that business logic can be handled and enforced inside your RDBMS. Good! But something to also consider in the real world is the fact that you generally have more web or application servers than database servers. So for scaling, loading the database servers more can be an inefficient use of resources. It can make more sense to spread such tasks across the web/app servers. Of course it's not a black&white story. Like any other tool, it has its positives and drawbacks and it should be used appropriately.

So, about doing weird things in SQL... Per-Erik Martin, the MySQL developer who led the implementation of stored procedures in MySQL 5.0, has written the following. It's an SQL implementation of a …