The latest from the MySQL community

What is often underestimated is impact of MySQL Performance by complex queries on large data sets(ie some large aggregate queries) and batch jobs. It is not rare to see queries which were taking milliseconds to stall for few seconds, especially in certain OS configurations, and on low profile servers (ie having only one disk drive) even if you just have one such query running concurrently.

Lets talk a bit how it is happening and how to prevent it.

Cache Wiping This is first reason for this to happen - query which crunches large amount of data set wipes data from your normal working set from OS cache. Operation Systems and MySQL Itself employs various strategies to attempt to minimize such effect but the truth is it still happens.

Disk Starvation As Cache efficiency drops more requests have to hit the disk, which may be 100% busy running your batch job query. This is especially bad when you …

I don't get it. I understand that Red Hat is a threat to operating systems companies everywhere, but I continue to find it highly ironic that its competitors proclaim cost savings for their customers...by shaving pennies from the least expensive part of the stack (the operating system).

Oracle did it with its "Unbreakable Linux." (Just picked up this shirt today, btw. Zack had it up on his blog and I thought it was too cool not to buy.) Oracle conveniently overlooked the fact that its database costs orders of magnitude more than the Linux the database runs on. If …

By Tim O'Reilly

Yesterday, I talked about the overall state of the computer book market. In this installment: category visualizations and trends showing which technologies are winning and which are losing in the book market. Here's a treemap view of the quarter on quarter differences between Q4 of 2006 and the same period last year:

As I've previously described in Book Sales as a Technology Trend Indicator, in a Treemap visualization, the size of a square indicates the relative size of the category, and its color indicates the rate of change. A category that is bright green is up significantly. One that is bright red is heading strongly in the …

I am happy to announce version 0.4 of mylvmbackup, a tool to perform consistent backups of a MySQL server's tables using Linux LVM snapshots.

For this release I'd like to especially thank Robin H. Johnson from the Gentoo project, who contributed another batch of useful changes and informed me that mylvmbackup is now in productive use to perform backups of the MySQL databases that power the project's Bugzilla bug tracking system. I am always glad to read about such use cases - how do you utilize mylvmbackup in your environment?

• The option handling has been improved. mylvmbackup now starts by using the builtin defaults, followed by the default configuration file (/etc/mylvmbackup.conf, followed by an alternative configuration file (specified via CLI …

At the MySQL Mini Conference in Sydney this week we discussed how to use EXPLAIN EXTENDED to view the rewrites undertaken by the MySQL optimizer.  IN particular, to see if MySQL performs a merge of the query into the view definition, or if it creates a temporary table.

It can be tricky to optimize queries using views, since it's often hard to know exactly how the query will be resovled - will MySQL push merge the text of the query and the view, or will it use a temporary table containing the views result set and then apply the query clauses to that?

In general, MySQL merges query text except when the view definition includes a GROUP BY or UNION.  But to be sure we can use EXPLAIN EXTENDED.  This also helps when we get confusing output in the EXPLAIN output.

For instance if we have a view definition like this:

CREATE VIEW user_table_v AS
     …

In case anyone has seen spurious problems using MySQL version 5.0.32 (and presumably the identical 5.0.33 community version) you might want to take a look at MySQL Bugs #25653 and #25596. They are about a little (but serious) InnoDB bug.

If you do not yet use this version, you might consider waiting for a fixed release to become available.

In case anyone has seen spurious problems using MySQL version 5.0.32 (and presumably the identical 5.0.33 community version) you might want to take a look at MySQL Bugs #25653 and #25596. They are about a little (but serious) InnoDB bug.

If you do not yet use this version, you might consider waiting for a fixed release to become available.

I find the new iPhone to be conceptually very interesting. Now, I am very new to the world of PDAs— I have only just started using one, a cast-off Palm Pilot from someone, and already I am thinking of things that it should be able to do but doesn't, or I haven't learned how yet. I suspect that very shortly I will be wondering how I got along without a PDA all these years.

Now, this new iPhone from Apple (I hope that they win the name from Cisco, as I have never ever heard of a Cisco iPhone but the name seems to naturally fit alongside iPod and other Apple products) will apparently be running a version of OSX. I find this very intriguing, because it opens up all sorts of interesting possibilities, including perhaps being able to run MySQL on it, or at least a client, perhaps a small database replicated from a fixed or not-as-mobile source.

At first glance and after hearing various reports, it sounds like a very capable …

At LCA I'm currently in Tridge's session on CTDB - Clustered TDB. This is a clustered version of his little database library, for clustered Samba.
Due to the different semantics it has a different API from TDB.
There's some very interesting stuff in there - obviously, it's not a general purpose database. It's asynchronous, event driven. No locking across the network. It aims for speed rather than reliability. In the case of Samba, it can afford for that specific data to be lost in extreme situations. It's not file data!

Brian, did you see this stuff already?