Question what is better isolation level is poping up again and again. Recently it was discussed in InnoDB : Any real performance improvement when using READ COMMITED isolation level ? and in Repeatable read versus read committed for InnoDB .
Serge in his post explains why READ COMMITED is better for TPCC load, so
why don't we take tpcc-mysql bencmark and check on results.

I took 3 different datasets 1000w (100GB of data), 300w (30GB) and 10w (1GB) for box with 32GB of RAM and buffer_pool 26GB. Latest case 10w is interesting as I expect a lot of contention on row level having small dataset.
I used as usually tpcc-mysql benchmark with 16 and 32 (for 10w) concurrent users.

Also I had binary log enabled on RBR mode (as READ-COMMITED does not support STATEMENT …

csplit backup.sql /"^-- Current Database"/ {*}; for f in xx*; do cat xx00 "$f" | mysql& done;

and then rm xx* when the background jobs have finished.

I haven't done any benchmarking, and I haven't worked out what to do if the number of databases exceeds the number of available connections.

Today a customer with corrupted data files showed up. When we enquired a bit more he told us that he had a broken I/O controller. This is one of the worst things which can happen to you!

The reason is the following: When a I/O controller starts to die it often does not happen immediately. The controller dies slowly producing more and more corrupt data. When you just write data without checking or reading them it can take days or even weeks until you discover the problem.

But the nasty thing is, that even your backup is infected with the corrupted data. In worst case corruption started long before your oldest still existing backup was made.

Fortunately DBMS are a bit sensitive related to data corruptions and start to complain pretty early. So please consider warning or error messages about data corruption as serious and try to find the problem immediately and solve it!

What can we do …

Today a customer with corrupted data files showed up. When we enquired a bit more he told us that he had a broken I/O controller. This is one of the worst things which can happen to you!

The reason is the following: When a I/O controller starts to die it often does not happen immediately. The controller dies slowly producing more and more corrupt data. When you just write data without checking or reading them it can take days or even weeks until you discover the problem.

But the nasty thing is, that even your backup is infected with the corrupted data. In worst case corruption started long before your oldest still existing backup was made.

Fortunately DBMS are a bit sensitive related to data corruptions and start to complain pretty early. So please consider warning or error messages about data corruption as serious and try to find the problem immediately and solve it!

What can we do against spreading data …

Today a customer with corrupted data files showed up. When we enquired a bit more he told us that he had a broken I/O controller. This is one of the worst things which can happen to you!

The reason is the following: When a I/O controller starts to die it often does not happen immediately. The controller dies slowly producing more and more corrupt data. When you just write data without checking or reading them it can take days or even weeks until you discover the problem.

But the nasty thing is, that even your backup is infected with the corrupted data. In worst case corruption started long before your oldest still existing backup was made.

Fortunately DBMS are a bit sensitive related to data corruptions and start to complain pretty early. So please consider warning or error messages about data corruption as serious and try to find the problem immediately and solve it!

What can we do against spreading data …

I would like to point the crowd to the Call For Presentaions of Loadays. , the Linux Open Administration Days .

The Linux Open Administration days 2010 will be the first edition of a new conference focusing on Linux and Open Administration, we are trying to fill a gap for System Engineers and Administrators using Open Source technologies"

More details on the Linux Open Administration Days site

I'll probably be there .. given the fact that the event will be 5 minutes from where I live .

Technorati Tags: antwerpen cfp conference drupal …

I've been using heidisql from the begining. After 4th version i was thinking all those new features were awesome !!!. but this time heidisql is beyond of it's all borders. i'm waiting for a stable version even if beta is enough. you guys nearly rewritten the whole code. thank you for your efforts... it's pity there are still shareware mysql frontends lives out there that can not success even half of Heidisql can.

From the Changelog:

C++ interface for libhashkit.
Modified memcached_set_memory_allocators() so that it requires a context pointer.
memcached_clone() now runs 5 times faster.
Functions used for callbacks are now given const memcached_st.
Added MEMCACHED_BEHAVIOR_CORK.
memslap now creates a configuration file at ~/.memslap.cnf
memcached_purge() now calls any callbacks registered during get execution.
Many fixes to memslap.
Updates for memcapable.
Compile fixes for OpenBSD.
Fix for possible recursive decent on IO failure.

Possibly the most exciting piece is the performance wins for memcached_clone(). In a lot of situations developers use libmemcached with Apache. Each time an Apache process has to be created a clone() call is made (in some PHP architectures this happens with each request). On local testing this went from around ~300ms for me, down to …

Before undertaking such migration the first step is a lesson in understanding more about how latin1 and utf8 work and interact in MySQL. latin1 in a common and historical character set used in MySQL. utf8 (first available in MySQL Version 4.1) is an encoding supporting multiple bytes and is the system default in MySQL 5.0

• latin1 is a single byte character set.
• utf8 is a 1-3 byte character set depending on the size of the character. NOTE: MySQL utf8 does not support the RFC 3629 4 byte sequences

MySQL variables

MySQL has a number of different system variables to consider, the following is the default representation in MySQL 5.1

mysql> show global variables like '%char%';
+--------------------------+----------------------------------------------------------------+
| Variable_name            | Value …

Kristian Nielsen presented “Beyond MySQL GA: patches, storage engines, forks, and pre-releases”.
This included a history of current products:

Google Patches (5.0 & 5.1) included improvements in :

• statistics/monitoring
• lock contention
• binlog
• malloc()
• filesorts
• innodb I/O and wait statistics
• SHOW …STATISTICS statements
• smp scalability
• I/O scalability
• semisync replication
• many more

Percona Patches (5.0) focus on

• statistics/monitoring
• performance/scalability
• buffer pool content/mutexes
• microslow patch

These have been ported to 5.1 and mainly integrated into XtraDB.

EBay Patches (5.0) have included:

• variable length memory storage engine
• pool of …