Home |  MySQL Buzz |  FAQ |  Feeds |  Submit your blog feed |  Feedback |  Archive |  Aggregate feed RSS 2.0 English Deutsch Español Français Italiano 日本語 Русский Português 中文
Previous 30 Newer Entries Showing entries 61 to 90 of 1146 Next 30 Older Entries

Displaying posts with tag: Databases (reset)

An unexplained connection experience
+0 Vote Up -0Vote Down

The “Too many connections” problem is a common issue with applications using excessive permissions (and those that grant said global permissions). MySQL will always grant a user with SUPER privileges access to a DB to investigate the problem with a SHOW PROCESSLIST and where you can check the limits. I however found the following.

mysql> show global variables like 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 2000  |
+-----------------+-------+
1 row in set (0.00 sec)

mysql> show global status like 'max%';
+----------------------+-------+
| Variable_name        | Value |
+----------------------+-------+
| Max_used_connections | 6637  |
+----------------------+-------+
1 row in set (0.00 sec)

How can the max_used_connection exceed max_connections? This is

  [Read more...]
Learn MySQL for Free with MySQL Marinate, Season 3!
+1 Vote Up -0Vote Down

The 3rd season of MySQL Marinate begins October 1st, 2013*. Join the meetup group and RSVP at season 3 to join! You can do the work on MySQL, or if you prefer, MariaDB or Percona.

If you do not have the book yet, you can still do the first week by using the online material from “Browse Contents” on the O’Reilly book page for Learning MySQL. There is homework for week 1, see the master list for all the information.

If you would like to learn MySQL from the ground up, consider joining us. This is for beginners – If you have no

  [Read more...]
A friday MongoDB funny
+1 Vote Up -0Vote Down

I had to laugh (just a bit) at this on the exhibitor floor at Oracle Open World 2013. There was a large MongoDB presence at the Slot 301. There are a few reasons.
First, the identity crisis remains. There is no MongoDB in the list of exhibitors, it’s 10gen, but where is the 10gen representation in the sign. 99.99% of attendees would not know this.
Second, the first and only slide I saw (as shown below), tries to directly compare implementing a solution to Oracle. The speaker made some comment but I really zoned out quickly. Having worked with MongoDB, even on one of my own projects, contemplated the ROI of being proficient in this for consulting, even discussing at length with the CEO and CTO, and hearing only issues with MongoDB with existing MySQL clients, I have come

  [Read more...]
SQL to Hadoop and back again, Part 1: Basic data interchange techniques
+0 Vote Up -0Vote Down

I’ve got a new article, which is part of a new three-part series, on moving data between SQL and Hadoop, both the export to Hadoop and importing processed content back into an SQL store.

In this first one, we look at the basic mechanics and considerations before you start the migration of data, such as the data format, content, and export techniques.

Read: SQL to Hadoop and back again, Part 1: Basic data interchange techniques


MySQL Puppet Module and Slides
+1 Vote Up -0Vote Down

During yesterday’s MySQL Connect conference, Brandon Johnson and I gave a joint talk about how Mozilla uses puppet to manage hundreds of MySQL servers efficiently. We also released our mysql puppet module on github, so that all can benefit. The slides for the talk are at http://bit.ly/puppet-mysql-slides.

Upgrading to MySQL 5.6 Slides
+1 Vote Up -0Vote Down

I am about to give a talk at MySQL Connect about what you need to know before upgrading to MySQL 5.6.

The PDF slides are online at http://bit.ly/upgrade56. I will be posting a video in the next few weeks!

A Brief Introduction to MySQL Fabric
Employee +2 Vote Up -0Vote Down
As you saw on the keynote, we are introducing an integrated framework for managing farms of MySQL servers with support for both high-availability and sharding. It should be noted that this is a very early alpha and that it at this point is not ready for production use.

MySQL Fabric is an integrated system for managing a collection of MySQL servers and is the framework on which high-availability and sharding is built. MySQL Fabric is open-source and is intended to be extensible, easy to use, and support procedure execution even in the presence of failure, an execution model we call resilient execution.

To ensure high-availability, it is necessary to have redundancy in the system. For database systems, the redundancy traditionally takes the form of having a primary server acting as a master and using replication to keep secondaries



  [Read more...]
Second Madrid MySQL Users Group taking place tomorrow Thursday, 12th September
+0 Vote Up -0Vote Down

If you happen to have some free time tomorrow and are in Madrid please come along to the second Madrid MySQL Users Group.

Details can be found here. The meeting will be in Spanish. I look forward to seeing you.

Video: Getting Started with Performance Schema
+2 Vote Up -0Vote Down

Recently I gave a new talk to both the Tokyo and Boston MySQL User Groups about how to get started using performance schema. I have put some resources online for those interested:

Performance Schema talk video

PDF slides

The feedback has been excellent, so I hope that you find this video useful when trying to learn how to use performance schema and dive into the depth of the information it provides you.

Measuring MySQL Query Performance
+0 Vote Up -0Vote Down

Measuring how well a MySQL is doing can be tough – most metrics are simply proxies for actual performance. Thankfully, the Percona build of MySQL allows you to see exactly how long your queries are taking. It provides a diagnostic view that shows how long queries take, allowing you to gauge its real-world performance. I’ll get to that in a little bit. Before we do that, I want to talk about some other tools you can use.

You can dump the status of the system by running “show global status;”. This will give you how many connections have aborted, rows written, and

  [Read more...]
Additional DB objects in AWS RDS
+0 Vote Up -0Vote Down

To expand on Jervin’s Default RDS Account Privileges, RDS for MySQL provides a number of routines and triggers defined the the ‘mysql’ meta schema. These help in various tasks because the SUPER privilege is not provided.

SELECT routine_schema,routine_name
FROM information_schema.routines;
+----------------+-----------------------------------+
| routine_schema | routine_name                      |
+----------------+-----------------------------------+
| mysql          | rds_collect_global_status_history |
| mysql          | rds_disable_gsh_collector         |
| mysql          | rds_disable_gsh_rotation          |
| mysql          | rds_enable_gsh_collector          |
| mysql          | rds_enable_gsh_rotation           |
| mysql          | rds_kill
  [Read more...]
MySQL MHA and Perl pathing
+1 Vote Up -0Vote Down

I am certainly not a knowledgeable Perl person, however I recently ran into the error Can’t locate MHA/MasterMonitor.pm on Red Hat 6.x. I have installed MySQL MHA on various systems before without any issues.

$ masterha_manager -version
Can't locate MHA/MasterMonitor.pm in @INC (@INC contains: /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at /usr/bin/masterha_manager line 26.
BEGIN failed--compilation aborted at /usr/bin/masterha_manager line 26.

The issue was that MySQL MHA is not installed in any of the acceptable default paths for this disto default installation.

$ find / -type d -name MHA
/usr/lib/perl5/vendor_perl/MHA

The fix was simple on this OS, but I expect there is

  [Read more...]
Cloning MySQL 5.6 instances
+1 Vote Up -0Vote Down

A tip for all those cloud users that like cloning database servers (as reported in my book Effective MySQL – Replication Techniques in Depth).

Starting with MySQL 5.6, MySQL instances have a UUID. Cloning servers to quickly create slaves will result in the following error message.

mysql> SHOW SLAVE STATUS\G
...
  Last_IO_Error: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server UUIDs; these UUIDs must be different for replication to work.
...

The solution is simple. Clear our the file based configuration file (located in the MySQL datadir) and restart the MySQL instance.

$ rm -f /mysql/data/auto.cnf
$ service mysql restart
Unnecessary 3am (emergency) call
+1 Vote Up -0Vote Down

Help, the database is on fire. Well, it probably is but the solution may also be easy. Here are a few steps for the part-time MySQL DBA/sysadmin/developer. Total time to address this solution was 2 minutes, the inability to not go back to sleep, not priceless.

First, access to the DB server is possible, and also the mysql command line client. If you are getting “Too Many Connections” read Why GRANT ALL is bad.

Given the message “the database is on fire”, the likely cause is rogue SQL.

mysql> show global variables like 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 5000  |
+-----------------+-------+
1 row in set (0.02 sec)

mysql> show global status like 'threads%';
  [Read more...]
Identifying empty tables in MySQL
+0 Vote Up -1Vote Down

The following simple INFORMATION_SCHEMA statement will identify and also verify tables that have no rows. These may be candidate tables to remove from your data model.

mysql --defaults-file=.my.cnf -N -e "select CONCAT('SELECT \"',table_schema,'.',table_name,'\" AS tbl, COUNT(*) AS cnt FROM ',table_schema,'.',table_name,';') as cmd from information_schema.tables where table_schema not in ('mysql','performance_schema','information_schema') and table_rows=0;" | mysql --defaults-file=.my.cnf -N
Indexing Talk Online
+1 Vote Up -1Vote Down

I am doing a quick blog post to announce that I have put an indexing talk online*. Most recently, I delivered this indexing talk at Confoo and Scale 11x.

The talk is on YouTube at Are You Getting the Best Out of Your MySQL Indexes? There are also PDF slides.
From the official conference description, if you want to know more:
MySQL indexes are often used to make performance better. However, they can make performance suffer if you are not using them properly. Oracle ACE Director Sheeri Cabral explains the pitfalls to avoid with indexes and how to utilize compound indexes to maximize index availability with the least amount of write overhead.

*I know I have not



  [Read more...]
A simple FAILED SQL statement breaks MySQL 5.6 replication
+1 Vote Up -0Vote Down

I setup 6 shiny new MySQL 5.6.13 MySQL servers, ready for testing and production deployment tomorrow.

I found that the New Relic MySQL Monitoring was throwing the following error.

[2013-08-08 03:53:33 +0000] com.newrelic.plugins.mysql.MySQL | SEVERE | An SQL error occured running 'SHOW ENGINE INNODB STATUS' Access denied; you need (at least one of) the PROCESS privilege(s) for this operation

Simple fix, the user I am gathering metrics requires the PROCESS privilege. Again simple enough.

mysql> grant PROCESS on xxx.* to xxx@'10.%';
ERROR 1221 (HY000): Incorrect usage of DB GRANT and GLOBAL PRIVILEGES
mysql> grant PROCESS on *.* to xxx@'10.%';
Query OK, 0 rows affected (0.00 sec)

As you can see I got

  [Read more...]
Developing Applications for use with Continuent Tungsten and Tungsten Replicator in SDJ
+1 Vote Up -0Vote Down

I’ve just had a new article published with the Software Developers Journal talking about how you can write applications to take full advantage of Continuent Tungsten and Tungsten Replicator.

As a developer of an application there really isn’t a problem better than finding that you have to scale up the application and the database that supports it to handle the increased load. The main bottleneck to most expansion is the database server and in many modern environments that replication is based around MySQL. Application servers are easy to add on to the front-end of your environment.

Read: Qt5 – How to Become a Professional

  [Read more...]
DP#8 The disadvantages of row at a time processing
+0 Vote Up -0Vote Down

It can be hard for software engineers to understand the following principle, however it is very important for improving performance and obtaining immediate scalability options. The principle is “Do Less Work”. That is, run less SQL statements.

Just one method to achieving the execution of less SQL statements is to eliminate Row At a Time (RAT) processing. In simple terms, do not perform identical repeating SQL statements in a loop. Relational algebra, and the Structure Query Language (SQL) specification is specifically designed to work with sets of data, or as I describe, Chunk At a Time (CAT) processing.

Customer Example

Your online social media website lets you send messages to multiple friends at one time. You enter the message, select the friends you want to receive the message and click send.

  [Read more...]
MySQL configuration file created in /usr/my.cnf
+0 Vote Up -0Vote Down

As part of uncovering a new security improvement in MySQL 5.6 with the default installation being secured with a unique root MySQL password, the MySQL provided rpm’s installed the MySQL configuration file in /usr.

I feel this maybe a bug, however this is just as an explanation for others to comment on.
The following steps reproduces this.

1. Launch a CentOS 6.4 AWS EC2 Instance

LOG=/tmp/create-instance.tmp.$$
INSTANCE_TYPE=m1.medium
ec2-run-instances ami-eb6b0182 --instance-type ${INSTANCE_TYPE} --region us-east-1 --availability-zone us-east-1b --key db --group db | tee ${LOG}
INSTANCE=`grep ^INSTANCE ${LOG} | awk '{print $2}'`
ec2-describe-instances ${INSTANCE} | tee ${LOG}
while [ `grep ^INSTANCE ${LOG} | awk '{print $6}'` !=

  [Read more...]
DP#4 The importance of using sql_mode
+0 Vote Up -0Vote Down

What if the data you retrieved from the database did not match the data the application claimed to had successfully stored? How comfortable would your organization feel about your skills and the products that are being used to store important information if data integrity was not guaranteed?

MySQL employs a terrible default technique known as silent truncation where the product determines that it knows about your data better than you. Never has the saying “do not assume” because it makes an “ass” out of “u” and “me” been more applicable.

Customer Example

A HTML form for new customers provide input fields for the customer first and last name. Good design was considered with the HTML form client validation to ensure that each field could not exceed 20 characters in length. However, the database design

  [Read more...]
Unexplained (trivial) MySQL behavior
+0 Vote Up -0Vote Down

The -N or –skip-column-names is a convenient option with the mysql client to skip the header line of output.
However I found when viewing the output via the terminal, some interesting and unexplained output.

$ mysql -h*** -u*** -p -e "SELECT VARIABLE_NAME,VARIABLE_VALUE FROM INFORMATION_SCHEMA.GLOBAL_STATUS"
+--------------------------------+----------------+
| VARIABLE_NAME                  | VARIABLE_VALUE |
+--------------------------------+----------------+
| ABORTED_CLIENTS                | 710001         |
| ABORTED_CONNECTS               | 31             |
| BINLOG_CACHE_DISK_USE          | 0              |
| BINLOG_CACHE_USE               | 0              |
| BYTES_RECEIVED                 | 2522301004     |
| BYTES_SENT                     | 317785976      |
| COM_ADMIN_COMMANDS             | 2890667        |
| COM_ASSIGN_TO_KEYCACHE

  [Read more...]
Improved Security with MySQL 5.6
+3 Vote Up -0Vote Down

Installed on a clean CentOS 6.4 AWS instance.

sudo su -
cd /tmp
wget http://cdn.mysql.com/Downloads/MySQL-5.6/MySQL-5.6.13-1.el6.x86_64.rpm-bundle.tar
tar xvf MySQL-5.6.13-1.el6.x86_64.rpm-bundle.tar
yum install -y libaio perl
rpm -i MySQL*.rpm

The following output is the sign that security is being considered with new MySQL versions. Woot!

A RANDOM PASSWORD HAS BEEN SET FOR THE MySQL root USER !
You will find that password in '/root/.mysql_secret'.

You must change that password on your first connect,
no other statement but 'SET PASSWORD' will be accepted.
See the manual for the semantics of the 'password expired' flag.

Also, the account for the anonymous user has been removed.

In addition, you can run:

  /usr/bin/mysql_secure_installation

which will also give you the option of removing the test database.
This is strongly recommended for
  [Read more...]
MySQL Presentations to the Colombia Oracle Users Group
+1 Vote Up -1Vote Down

My slides for presentations on MySQL Backup and Recovery Essentials and Understanding and using MySQL in the Cloud from the Oracle Technology Network (OTN) event in Medellín‎ Colombia are now available.

Thank you to the Colombia Oracle Users Group for inviting me to the event.

MySQL Proxy and microseconds
+1 Vote Up -0Vote Down

By default the included Lua within MySQL proxy (0.8.3) does not include socket, necessary for getting microsecond granularity. To setup you have to install Lua and socket on the OS first:

For CentO5

$ sudo yum install lua lua-socket

For Ubuntu

$ sudo apt-get install lua5.1 liblua5.1-socket2

The following enables use within MySQL Proxy.

cp /usr/share/lua/5.1/socket.lua /path/to/mysqlproxy/lib/mysql-proxy/lua
cp -r /usr/lib64/lua/5.1/socket /path/to/mysqlproxy/lib/mysql-proxy/lua
cp -r /usr/lib64/lua/5.1/mime /path/to/mysqlproxy/lib/mysql-proxy/lua

My lua script can now use syntax similar to:

require 'socket'

function read_query( packet )
...
  now=socket.gettime()
  print( string.format("# %s.%3d\n%s;\n",os.date("%X",now),select(2,math.modf(now))*1000 , query))
MySQL Monitoring With Cacti Using Percona Monitoring Plugins (1-minute resolution)
+0 Vote Up -0Vote Down

Today, just like many times before, I needed to configure a monitoring server for MySQL using Cacti and awesome Percona Monitoring Templates. The only difference was that this time I wanted to get it to run with 1 min resolution (using ganglia and graphite, both with 10 sec resolution, for all the rest of our monitoring in Swiftype really spoiled me!). And that’s where the usual pain in the ass Cacti configuration gets really amplified by the million things you need to change to make it work. So, this is a short checklist post for those who need to configure a Cacti server with 1 minute resolution and setup Percona Monitoring Plugins on it.

Configuring Cacti for 60-seconds polling

First of all, we

  [Read more...]
My MySQL bugs and feature requests
+1 Vote Up -0Vote Down

My MySQL bugs is a list I recently created and intend to keep up to date with issues I have seen.

First Madrid MySQL Users Group scheduled for the 4th July
+0 Vote Up -0Vote Down

As mentioned here and after talking to a few people we have created a meetup page, http://www.meetup.com/Madrid-MySQL-users-group/ and proposed the first meeting on Thursday, 4th July. If you are interested and in the area come along and say hello. It should be interesting to see a few others who work in the field.  If you can let us know you are coming so we have an idea of how much interest there is.

Announcing the MySQL Plugin for New Relic
+2 Vote Up -0Vote Down

Many application developers would know of New Relic. A SaaS performance and monitoring tool targeted towards your web application monitoring including PHP, Ruby, Java, .Net, Python and Node.

With the release today (June 19, 2013) of the New Relic Platform, custom monitoring of data stores including MySQL are now possible. Try it now free. This link will provide you a free standard account (no cost, no billing details necessary), that enables you to perform application monitoring, server monitoring, MySQL instance monitoring and monitoring of many other products via many plugins.

Over the next few posts I will be discussing some of the design decisions I made for this MySQL plugin. New

  [Read more...]
On operating system upgrades and a packager’s nightmare
+1 Vote Up -0Vote Down

A fairy tale

Once upon a time I did an operating system upgrade, a minor one that should do no harm, but just get me up to date by fixing any bugs in the version I had been using. It seemed like a good idea.

All seemed to be fine. I use a package provided by an external vendor and not the one produced by the operating system provider as this vendor provides a newer version of the package and I need that. The vendor has to make his package fit in the os environment his package is built for and normally does a pretty good job.

I use automation to build my systems and when I built a new one some issues appeared. Related to the new version of the OS the provider had enhanced one of his packages and the installation pulled in new dependencies. The install of the external package I use then broke as it conflicted with the new dependency

  [Read more...]
Previous 30 Newer Entries Showing entries 61 to 90 of 1146 Next 30 Older Entries

Planet MySQL © 1995, 2014, Oracle Corporation and/or its affiliates   Legal Policies | Your Privacy Rights | Terms of Use

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.