mysql> select count(*) from file_to_delete;
+----------+
| count(*) |
+----------+
| 40510413 |
+----------+

mysql> select count(*) from file_on;
+-----------+
| count(*) |
+-----------+
| 178473804 |
+-----------+



Was wondering about this:

host device size(G) used(G) free(G) use%
---- --------------- ---------- ---------- ---------- ------
[...]
---- --------------- ---------- ---------- ---------- ------
total: 3437.986 2722.549 715.437 79.19%


when:

mysql> select count(*) from file;
+----------+
| count(*) |
+----------+
| 19229098 |
+----------+

mysql> select (sum(length) / 1024) / 1024 from file;
+-----------------------------+
| (sum(length) / 1024) / 1024 |
…

The results are in, and MySQL came out on top. C't just did a comparison of different databases and found that MySQL is the "fastest database application." The magazine's editors held the contest to evaluate database performance in real-world business use by creating a standard online inventory system.

From the announcement:

"The DVD shop created by MySQL is the hands-down winner of the performance crown. It clearly demonstrates the capabilities of a carefully configured MySQL/PHP application.”The MySQL DVD online store was able to process 3,664 orders per minute (opm). If a second computer had been used, the figure would have gone up to 6,000 opm, indicating that MySQL is business ready. No more of this silly nonsense about it being a low-end utility database. Nothing could be farther from the truth.

(You can see the full results from the contest …

So I've set up this cast-aside laptop as a machine to do pulls from BitKeeper and do builds and installs and it's working pretty well. I was able to do pulls of six different versions of MySQL and build them. They are now happily running simultaneously.

Then I went away for three days, taking my younger daughter to boarding school where she is starting as a freshman in high school. At the same time my older daughter is off to college so the nest is now basically empty. But I digress.

I said 'was' because shortly after that a couple bugs manifested, one as noted before and one new one which I was pleased to report and have verified. I have been following the …

So I've set up this cast-aside laptop as a machine to do pulls from BitKeeper and do builds and installs and it's working pretty well. I was able to do pulls of six different versions of MySQL and build them. They are now happily running simultaneously.

Then I went away for three takes, taking my younger daughter to boarding school where she is starting as a freshman in high school. At the same time my older daughter is off to college so the nest is now basically empty. But I digress.

I said 'was' because shortly after that a couple bugs manifested, one as noted before and one new one which I was pleased to report and have verified. I have been following the …

Update: As some people have pointed out, if this is on all the time in a production environment, it could be bad. We only enable it when debugging. But, in the interest of keeping the PHP world safe, I have edited the code.

Preface: I would not use this in a production environment on a full time basis.  When we do use it, we turn it on, gather some logs and turn it off.  Also, it has been pointed out to me that this will cause MySQL to not use the query cache in versions previous to 5.0.  That is another reason to not use this in a production environment full time.

So, on dealnews.com we often end up with a lot of queries that look kind of the same. It usually because we have a complex query that simply selects article ids from one or two tables and then a second query to select the data from the article table using those ids. If you have used MySQL …

As I explained in this blog, it’s always a difficult decision for me to keep postponing my own project in order to work on the patent policy front. But once again, like so many times before, I have decided to do so for some more time. Given what happened at the July 12 hearing, there are some important things to do right away. I’ll talk a little more about my personal future on some other occasion, but suffice it to say that I’m still actively involved in the European patent policy debate!

This spring I have added some new modules to our system. The old ones are all based on Microsoft SQL Server, but for the new ones we decided to go with MySQL as a part of a strategy of moving to MySQL with the whole system. We decided to use InnoBase as a storage engine and Hibernate for accessing the database from our Java application. No strange decisions, I believe.

The development phase is now over, with no major problems, and the system is up and running. During this autumn we will see how it works, but I'm nit very worried, it seems stable.

Unfortunately the customers strategy is today unclear, so we're stuck in a situation with two databases. Personally, I feel that using MS SQL Server in a Java environment is a questionable approach, since Microsoft is positioning the product as a part of the .net platform. And the 2000 version, which we are currently running, is getting old...

The wonder of film scanners. I have found a whole lot of old pictures on scratched up black and white film and dusty slides and with the scanner they are coming back. I'm considering doing a "picture every other day/week/..." thing. Hmmn..

Here's a picture from New York in the summer of 19925. Since this is my geeky weblog, then let me put it in those terms: Before I did Perl.Several years before I used OS/2. Four yearsA year before my first Linux box. Years before I used MySQL.

Oh, and before 2001 - obviously.

(See also large size, or the Flickr Entry if you want to mark it a favorite).

update: maybe it was 1995 and not 1992...

Wrapped up a few final touches this evening on the memcache engine:
http://tangent.org/index.pl?lnode_id=506

What works:
SELECT, UPDATE, DELETE, INSERT
INSERT into foo SELECT ...

What doesn't work?
Probably ORDER BY operations.
REPLACE (I think)
IN ()
NULL
multiple memcache servers (this would be cake though to add)
table namespace, right now it treats the entire server as one big namespace

There is probably a lot more I haven't thought up that is now working. Right now the version I put up only allows you to have a primary key and one attribute. Doing multiple attributes means coming up with a way to store MySQL row format, aka UNIREG, in something which would be easy for anyone to take apart. Mark suggested XML, but XML would be damn slow to parse.

If …

I've been writing a lot of articles about locks, deadlocks, and transactions recently, and it occurs to me I've neglected to mention the single most important thing to know. If you only learn one thing about transactions in database systems, you should learn this, and learn it thoroughly -- burn it into your brain permanently, if possible.