This is short chapter which gives some clue what to do with concurrent transactions.

Chapter 7. Concurrent transactions.

Yet another frequent example of similar problem is "Lock wait timeout
exceeded" error while you use InnoDB tables. Most often running query
SHOW ENGINE INNODB STATUS is enough to find the problem, because it
will show last transactions. But output of this command does not
contain information about all queries in the same transaction, but only
about last one. What to do if SHOW ENGINE INNODB STATUS doesn't provide
all information?

...

 Rest of the chapter is here

ANDROID SMART PHONE

Senior DATA WAREHOUSING ENGINEER

“We are at the intersection of all things cool in the valley”

We are a Sunnyvale, CA based software applications and services development
team in the heart of Silicon Valley that is combining the best of the internet,
messaging, and social networking into intuitive software, called MOTOBLUR.
MOTOBLUR is an innovative cloud-assisted solution to manage and integrate
messaging, social networking, and other web services and will debut on the
T-Mobile/Motorola CLIQ with MOTOBLUR Android smartphone. This product
aggregates contacts, posts, messages, photos and more from sources including
Facebook®, Twitter™, MySpace®, Gmail™, and Microsoft Exchange and many more to
come.

In collaboration with Google’s Android team, we …

This is short chapter which gives some clue what to do with concurrent transactions.

Chapter 7. Concurrent transactions.

Yet another frequent example of similar problem is "Lock wait timeout
exceeded" error while you use InnoDB tables. Most often running query
SHOW ENGINE INNODB STATUS is enough to find the problem, because it
will show last transactions. But output of this command does not
contain information about all queries in the same transaction, but only
about last one. What to do if SHOW ENGINE INNODB STATUS doesn't provide
all information?

...

 Rest of the chapter is here

So lets imagine you have the server handling 100.000 user accounts. You can see the CPU,IO and Network usage is below 10% of capacity - does it mean you can count on server being able to
handle 1.000.000 of accounts ? Not really, and there are few reasons why, I'll name most important of them:

Contention - This is probably the most obvious one. MySQL (and systems in general) do not scale perfectly with numbers of CPUs and number of concurrent requests. Reduced efficiency of CPU cache, Mutex contention and database lock contention all come here. Some of them are preventable and can be reduced by code changes, such as there have been a lot of advanced in scalability of MySQL by improving locking code design, others, such as row level locks would require application changes to allow more concurrent process. The scalability numbers depend a lot on the system scale, software and workload.

Data size …

Hey DBAs! Are you seeking more efficient ways of shifting through your data to aid your business operations? Two popular Business Intelligence products have community Open Source software are Pentaho and JasperSoft. And both work with MySQL.

Both are easy to download and install. Both will use a JDBC connector to connect to MySQL. But how easy are the two to configure and run a simple report against a running instance of MySQL?


Setting up a JDBC connection with JasperSoft or Pentaho is pretty much like using any other JDBC connection.
The …

I am by now a few days late, but I meant to point out once the milestone had been reached:

MySQL Bug #11660, “Expose either SQLState, mysql_error() or other diagnostics in stored procedures” was opened on June 30, 2005. It has now been open for more than five years with no fix in the server, no fix in sight, and no real workaround. This makes it very difficult to recommend the use of MySQL stored procedures for most serious applications, as it is somewhere between very cumbersome and impossible to handle errors properly. How can something so important go so long without a fix?

…

In facebook stream you’ll see the time period at the bottom of the stream. For example: 4 minutes ago, 2 days ago, 3 weeks ago…. In our recent project we have to show similar time fashion for our application’s activity stream. So I write a function to retrieve the time duration. In our mysql database, [...]

…

After successfully Installing MySQL, let us take a look at an operational MySQL instance on your Oracle Enterprise Linux server.

User Management

By default there will be a new mysql user and group created. This user is used to run the mysqld process is generally not used for any other purpose.

$ grep mysql /etc/{passwd,shadow,group}
/etc/passwd:mysql:x:27:27:MySQL Server:/var/lib/mysql:/bin/bash
/etc/shadow:mysql:!!:14796::::::
/etc/group:mysql:x:27:

Binaries

MySQL binaries are found in /usr/bin.

$ ls -l /usr/bin/mysql*
-rwxr-xr-x 1 root root  314568 Feb 16 17:45 /usr/bin/mysql
-rwxr-xr-x 1 root root  110776 Feb 16 14:39 /usr/bin/mysqlaccess
-rwxr-xr-x 1 root root   35144 Feb 16 17:45 /usr/bin/mysqladmin
-rwxr-xr-x 1 root root  112944 Feb 16 …

This year we're participating in OSCON as a Sponsor and organizing some BOFs. I will be on the conference 21 and 22 if you're interested to chat.
Here is the list of currently scheduled BOFs which I'll be hosting:
Running Databases on Flash Storage
Sphinx Search 2010
XtraDB, XtraBackup, Maatkit, Percona Server
See you there.

Entry posted by peter | No comment

Add to: …

Many people use the MySQL MEMORY storage engine for applications where they don’t need their data to be highly available or even survive restarts. Where this works best is for applications that are dominated by reads and (obviously) where the data doesn’t need to survive any kinds of problems (or where it can be recovered from another source). Typical applications are :

• Caching of small tables to reduce the latency of database look-ups.
• Simple session management (i.e. with no analytics or reporting on the session data).
• Buffering of multiple updates for batched inserts into tables managed by other MySQL storage engines.  (Note requires additional custom application development).

While great for some applications (at least initially), as the application requirements start …