I’ve been using MySQL 5.1 a lot more of late. Also, as of about a month ago, I’m now a Mac OS X user, so tend to use MySQL on OS X Leopard 10.5 a lot more for testing. I’ve found a rather annoying bug (in 5.1.23-rc) that is fixed in the current source tree, and will be in 5.1.24-rc…

What’s annoying me? The fact that Control+R (which allows one to save typing, because you can go through the search history of ~/.mysql_history) segfaults the MySQL client. At first I thought something was wrong with my install when I saw the infamous “Segmentation fault” error. Turns out, its just mysql#33288.

I always hit ctrl+r without even thinking… Its just a shortcut ingrained in my fingers, because I predominantly use a shell. So, Mac OS X users can rejoice soon, as 5.1.24-rc is surely around the corner. In fact, there are numerous improvements, just read the …

I’m still looking for new entries. I get quite a few suggestions, but not all of them make it into quiz questions. Do send in your suggestions!

Here’s something I came across several months back. Watch in wonder as we create a PRIMARY KEY which is already there, then drop it again, only and to see that it’s still present in the table…:

mysql> DESC t1;
+-------+---------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+-------+---------+------+-----+---------+-------+
| i     | int(11) | NO   | PRI |         |       |
+-------+---------+------+-----+---------+-------+
1 row in set (0.00 sec)

mysql> ALTER TABLE t1 DROP PRIMARY KEY;
ERROR 1091 (42000): Can't DROP 'PRIMARY'; check that column/key exists
mysql> ALTER TABLE t1 ADD PRIMARY KEY(i);
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC t1;
+-------+---------+------+-----+---------+-------+
| …

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Venture capitalist Brad Feld just put up an intriguing post comparing Google App Engine to Amazon EC2. The meat of the entry is from an analysis by Brad's friend Scott Moody. Here are the juiciest bits, pro and con:

With EC2, you still have to set-up load balancers, configure multiple replicated database servers, implement scalability hacks if things grow too fast (such as distributed caching of data via memcached), keep distros and apps up-to-date, etc. Bottom Line: EC2-based companies still require sys admins, AppEngine companies don't. That will certainly change as more companies begin offering EC2 server management services.

Google provides a non-relational datastore and that's the only datastore available (no traditional file system, no relational databases). With EC2, people generally use MySQL or Postgresql. Amazon offers a …

The second and last tutorial of Monday was Memcached and MySQL: Everything you need to know by Brian Aker and Alan Kasindorf.

The talk was mainly about memcached and libmemcached and less on MySQL. That's OK since I have been meaning to learn more about memcached's internals.

Alan and Brian discussed the slab allocator, protocol, internal hash table, LRU (least recently used), and threading. The slab allocator is the name of memcached memory allocator. The LRU keeps track of the age of each slab. memcached uses a consistent hash algorithm for the slabs to be located quickly and supports dynamically adding new …

As per the Platinum Partners List PrimeBase Technologies has made a key achievement. I think this is a great list to make for the company. There are only 18 Platinum partners, and PrimeBase Technologies are the third Storage Engine provider and the second first open source storage engine company.

The News Release quotes “As a key milestone in our relationship with both the MySQL Community and MySQL, this partnership strengthens our commitment and involvement in working with the MySQL database server starting with PBXT and following with additional product developments.”

Update Thanks to Ken Jacobs, I need make a correct, we are not the first “open …

The day of tutorials started out with All Bases Covered: A Hands-on Introduction to High-availability MySQL and DRBD by Florian Haas and Philipp Reisner.

After a brief introduction to DRBD, they started discussing the configuration file. There were a couple settings that I had set incorrectly on my servers.

Since I have my two servers connected via a gigabit crossover cable, I had my synchronization rate set to 125MB. They recommended approximately 1/3 your network and disk I/O so that you're applications don't freeze up during synchronization. Their test system used 30MB so I'll give it a try too.

Another setting they had different was the activity log extents. All of the references I looked at said to set the al-extents …

Compiling and installing a User Defined Function for MySQL on Mac OS X seems tricky. There are installation notes, but they seem to be sparse on OS X (the comments are clues, though).

I was looking through the tutorial materials for Roland’s talk, and came up with what I think is the most full-proof way to ensure your UDFs get compiled…

gcc -Wall -dynamiclib -o udf_lightspeed.dylib -lstdc++ udf_lightspeed.c

The above will compile just fine, but MySQL will give you an interesting error saying “no suitable image found”. Its the infamous Error 1126.

Upon further poking, it seemed like the following should work:
gcc -Wall -dynamiclib -o udf_lightspeed.dylib -lstdc++ -lc -I`/usr/local/mysql/bin/mysql_config –cflags` udf_lightspeed.c

And it …

Thanks to Marcos Besteiro and Andrew Dashin, the MySQL Pop Quizzes are now available in Spanish and Russian!

Thanks for the hard work, guys! It’s great to see that people are finding this worthwhile. I will try to get around to linking up the individual quizzes as soon as I find some time.

If you wish to translate the quizzes into your own language, please contact me at carsten (at) bitbybit (dot) dk before you start so we can sort out the details.

Giuseppe Maxia blogs about the MySQL community dinner with some special guests in attendance.