Last few weeks I noticed a problem in the replication, where on and off the replication SQL thread fails to truncate a table with the following error:

      ERROR 1105 (HY000): MyISAM table 'XXXX' is in use (most likely by a MERGE table). Try FLUSH TABLES.

So, I was keep skipping the error, as it was fuzzy why when only one thread is actually executing (no other threads on DB other than slave SQL thread); and today it happened, and I got a simple repro:

 
mysql> drop table if exists t1, t2, merge;
Query OK, 0 rows affected, 3 warnings (0.05 sec)
 
mysql> create table t1(c1 int)Engine=MyISAM;
Query OK, 0 rows affected (0.03 sec)
 
mysql> create table t2(c1 int)Engine=MyISAM;
Query OK, 0 rows affected (0.06 sec)
 
mysql> insert into t1 values(10);
Query OK, 1 row affected (0.04 sec)
 
mysql> insert into t2 values(20);
Query OK, 1 row …

Only a little over a week before the User conference and I am still burning the midnight oil to get as much information for my presentations as possible. I thought I would tease you a bit here. What do you get when you put 4 Intel X-25E’s ( Sun branded) SSD’s running RAID10 in a Sun 4450 and run the sysbench fileio test on it?

when working on mutex contention for ndbapi (mysql-cluster)
i decided to do some micro benchmarks.

The benchmark is threads that locks/unlocks an private mutex
and increment a counter.

The tests are:

• mutex_aligned, pthread_mutex, lock/unlock, each mutex in separate cache-line
• mutex_non_aligned, same as above but mutexes are packed together hence sharing cache-lines
• spin_aligned, home-made spinlock (only x86), each spinlock in separate cache-line, the spinlock is an atomic operation for lock, and a full-barrier+assign for unlock
• spin_non_aligned, same as above but spinlocks are packed together hence sharing cache-lines
• lock_xadd, atomic-inc, (on sparc impl. using atomic.h, which uses cas i think)
• xadd, (only x86), the non-smp (but irq) safe add variant for x86
• gcc_sync_fetch_and_add, gcc intrinsic for atomic …

Sun Tech Days St. Petersburg was on Wednesday-Thursday the last week and we’ve had a MySQL booth there. Unlike the last year, we’re full part of Sun now so managed to get a decent-sized booth, arrange for leaflets, and Kostja gave an overall MySQL talk.

Questions at the booth (in no particular order):

• When will Connector.NET support LINQ Entity framework? (According to Reggie Burnett: it is currently supported in Connector 6.0/Beta, which is expected to be GA soon)
• Can Connector.Net be used with Mono? (Yes)
• Is Workbench available for Linux (Yes)
• When will MySQL support stored procedures? This question seems to have replaced the infamous “When will MySQL support transactions” question.
• What is the impact of different transaction …

mysqlsla is interesting tool to analyze slow log query, aggregate same query in one and generate unique sql statement withCount, (max, min, avg) execute time, lock time, Rows sent, Rows examined for each unique one.you can use it to review indexes and drop unused index, and create another.Report for slow logs: slowquery1day.txt791 queries total, 85 uniqueSorted by 't_sum'Grand Totals: Time 23.05k

I was reading through the manual and noticed that myisamchk parallel recover option is still listed as beta code. The feature was added in 4.0.2 which was released in july 2002. This means it’s been in beta longer than gmail

I haven’t really decided my schedule yet during the conference, but I thought I’d mention these sessions that look interesting to me.

I’m presenting a session on how to use Maatkit, which I think attendees will get a lot of benefit from.

• Tuesday
  • This is Not a Web App: The Evolution of a MySQL Deployment at Google (keynote). Mark Callaghan, need I say more?
  • MySQL and Search at Craigslist. Jeremy has gotten back into technical work after a career at Yahoo! that seemed to lead him away from his heart’s desire. I’d like to hear about the things he’s done, especially since I understand it involves replacing a lot of overloaded MySQL machines with a few underloaded Sphinx machines.
  …

Just reading up on the fuss around the rev=canonical proposal.

Maybe I'm completely missing the point, but even the "alternative shorter" proposal seems a bit idiotic to me. I'd like to take a step back and try to figure out what problem exactly we're trying to solve.

Why do we need to make our url's shorter?

Url's should be meaningful. We use url's very often, so being able to spot what a certain url is likely going to link to is very helpful. If, for some reason, creating a meaningful url is difficult, you definitely want to make sure the urls stay under a certain amount of characters. Long, bulky urls might be broken apart into multiple lines in emails and cause other usability issues.

Services like tinyurl fix that problem. It doesn't solve the …

I always say that the ultimate MySQL tuning script is an expert human. To that end, I generally try to build tools that help a human be more productive with the raw information from MySQL. One of the things we look at during a performance audit is the MySQL status counters. It’s useful to look at a) absolute values and b) several incremental snapshots. I’ve written a small shell script called “mext” that can make this a little easier.

It looks like this:

baron@kanga:~$ mext -- mysqladmin ext -ri1 -c3
Aborted_clients                               1      0      0
Aborted_connects                              0      0      0
Binlog_cache_disk_use                         0      0      0
Binlog_cache_use                              0      0      0
Bytes_received                             1167     35     35
Bytes_sent …

I just read about the release of Honey Monitor for MySQL. I read through the features. I looked at the screenshots. Then I read about the licensing. Then I read about the fact that it only runs on windows XP or Vista. So, my questions for the ages…

1. Why, in this age of multiple OSes battling each other for market share, would you write an application that is OS specific? Every app should run in a vendor neutral web browser unless there’s a really really good reason. Monitoring software, are you kidding? Monitoring software must be vendor neutral and web-based. I will never use anything that ties me to windows or linux or osx, it has to be cross platform. End of story.
2. Why, when MySQL is so heavily used on Linux and Solaris, would you write an application for MySQL that can only be run on Windows? Every MySQL DBA …