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Showing entries 1 to 30 of 16152 Next 30 Older Entries

Displaying posts with tag: mysql (reset)

Troubleshooting TokuDB Corruption
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I recently ran across some TokuDB table corruption, which was not easily identifiable at first, and the error log entry was not too verbose either, so I wanted to share that experience here.

Basically, TokuDB crashed, and then mysqld had problems restarting afterward. Just for reference, the error log had the following in the stack trace:

/usr/lib64/mysql/plugin/ha_tokudb.so(+0x71c48)[0x7fb25be75c48]
/usr/lib64/mysql/plugin/ha_tokudb.so(+0x71cbd)[0x7fb25be75cbd]
/usr/lib64/mysql/plugin/ha_tokudb.so(_Z29toku_deserialize_bp_from_disk...
/usr/lib64/mysql/plugin/ha_tokudb.so(_Z23toku_ftnode_pf_callback...
/usr/lib64/mysql/plugin/ha_tokudb.so(_Z30toku_cachetable_pf_pinned_pair..
/usr/lib64/mysql/plugin/ha_tokudb.so(_Z24toku_ft_flush_some_child...
/usr/lib64/mysql/plugin/ha_tokudb.so(_Z28toku_ftnode_cleaner_callback...
  [Read more...]
Troubleshooting TokuDB ERROR 1126 – API Version Mismatch or bitmap_free
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When setting up TokuDB, you may encounter error 1126.

I’ve seen 2 recent invocations of it, so I wanted to share them both here in case you run into this issue:

MariaDB [(none)]> install soname 'ha_tokudb';
ERROR 1126 (HY000): Can't open shared library
'/usr/lib/mysql/plugin/ha_tokudb.so' (errno: 2, undefined symbol: bitmap_free)
MariaDB [(none)]> install soname 'ha_tokudb';
ERROR 1126 (HY000): Can't open shared library 'ha_tokudb.so'
(errno: 8, API version for STORAGE ENGINE plugin TokuDB not
supported by this version of the server)

The latter is a bit more descriptive, but the former is fairly cryptic.

Given the latter, as you may have guessed it, if you run into either of these, you have the wrong version of ha_tokudb.so in your plugin directory – that is, it is not the correct version

  [Read more...]
Disabling Transparent Hugepages for TokuDB
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If you want to use TokuDB with MariaDB, MySQL, or Percona Server, you will need to disable support for transparent hugepages in Linux.

Fortunately, this is very easy to check, and to change.

An easy way to check is with:

cat /sys/kernel/mm/transparent_hugepage/enabled

This will return something like:

[always] madvise never

Note the word surrounded by “[]” is what this option is set to. So the above is set to “always”. To disable it, we want it set to “never”.

I’ve found the easiest way to change/set this is to add the below to your /etc/rc.local file (and then reboot your system):

if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
   echo never >
  [Read more...]
Enabling TokuDB in MariaDB is a Breeze
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TokuDB is gaining more and more popularity and many people are finding it very helpful for certain cases.

Using/enabling it in some distributions can be quite a pain, but enabling it in MariaDB is easy as 1-2-…, well, only 1-2, since that’s all there is to it!

1. Ensure you have the correct MariaDB version:

  • MariaDB 5.5.36+
  • MariaDB 10.0.9+
  • Note: Linux 64-bit systems only – specific packages include: Ubuntu, Debian, Fedora, CentOS, Red Hat
  • Note: If using the Linux tarball – it must be the version built with glibc 2.14+

2. Run this command:

INSTALL SONAME 'ha_tokudb';

or update my.cnf file with:

[mysqld]
plugin-load=ha_tokudb

There is one requirement from

  [Read more...]
Upgrade MySQL to a new version with a fresh installation & use shell scripts and mysqldump to reload your data
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There are several ways to upgrade MySQL (http://mysql.com). In this post, we will use a combination of shell scripts and the mysqldump application to export our MySQL (http://mysql.com) data, and then re-import it back into the upgraded version of MySQL (http://mysql.com).

In this example, we will be doing a minor version upgrade. We will be going from 5.6.17 to 5.6.19. This method may not work if you are upgrading from one major release to another – from 5.1 to 5.5, or 5.5 to 5.6. You will want to check each version and review the new features/functions and also what features/functions have been deprecated. We are also assuming that no one will be using the database during the time it takes

  [Read more...]
MySQL 5.5.39 Overview and Highlights
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MySQL 5.5.39 was recently released (it is the latest MySQL 5.5, is GA), and is available for download here:

http://downloads.skysql.com/archive/index/p/mysql/v/5.5.39

This release, similar to the last 5.5 release, is mostly uneventful.

There were two “Functionality Added or Changed” and 24 bugs fixed.

The “Functionality Added or Changed” changes are:

  • CMake support was updated to handle CMake version 3.
  • The timed_mutexes system variable has no effect and is deprecated.

Out of the 24 bugs, most seemed rather minor or obscure, but here are the ones I think are worth noting (crashing, security, wrong results, deadlock):

  • InnoDB: Opening a parent table that has thousands of child tables could
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MySQL Connector/Python on GitHub
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Last week we released Connector/Python v2.0 (alpha); today we publish the source on GitHub. Yes, we are using Git internally and are now able to push it out on each release. Previous versions are still available through LaunchPad.

Here is the full process to get Connector/Python installed in a virtual environment. You’ll need Git installed of course.

shell> git clone https://github.com/oracle/mysql-connector-python.git cpy
shell> virtualenv ENVCPY
shell> source ENVCPY/bin/activate
(ENVCPY)shell> cd cpy
(ENVCPY)shell> python setup.py install
(ENVCPY)shell> python
>>> import
  [Read more...]
Paris OpenStack Summit Voting – Percona Submits 16 MySQL Talks
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MySQL plays a critical role in OpenStack. It serves as the host database supporting most components such as Nova, Glance, and Keystone and is the most mature guest database in Trove. Many OpenStack operators use Percona open source software including the MySQL drop-in compatible Percona Server and Galera-based Percona XtraDB Cluster as well as tools such as Percona XtraBackup and 

  [Read more...]
MariaDB: Selective binary logs events
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In the first post in a series on MariaDB features we find interesting, we begin with selectively skipping replication of binlog events. This feature is available on MariaDB 5.5 and 10.

By default when using MySQL’s standard replication, all events are logged in the binary log and those binary log events are replicated to all slaves (it’s possible to filter out some schema). But with this feature, it’s also possible to bypass some events to be replicated on the slave(s) even if they are written in the binary log. Having those event in the binary logs is always useful for point-in-time recovery.

Indeed, usually when we need to not replicate an

  [Read more...]
Percona Server 5.1.73-14.12 is now available
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Percona Server version 5.1.73-14.12

Percona is glad to announce the release of Percona Server 5.1.73-14.12 on July 31st, 2014 (Downloads are available here and from the Percona Software Repositories). Based on MySQL 5.1.73, including all the bug fixes in it, Percona Server 5.1.73-14.12 is now the current stable release in

  [Read more...]
Testing that all projects need
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Today, I was reminded of a Jim Starkey quote on the Random Query Generator:

“The Colonoscopy of Database Software”
- Jim Starkey

If your project does not have something that you can adapt that quote to, odds are your testing is inadequate.

Examining the TokuDB MySQL storage engine file structure
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As we know different storage engines in MySQL have different file structures. Every table in MySQL 5.6 must have a .frm file in the database directory matching the table name. But where the rest of the data resides depends on the storage engine.

For MyISAM we have .MYI and .MYD files in the database directory (unless special settings are in place); for InnoDB we might have data stored in the single table space (typically ibdata1 in the database directory) or as file per table (or better said file per partition) producing a single file with .ibd extension for each table/partition. TokuDB as of this version (7.1.7) has its own innovative approach to storing the table contents.

I have created the table in the database test having the following

  [Read more...]
Prevent MySQL downtime: Set max_user_connections
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One of the common causes of downtime with MySQL is running out of connections. Have you ever seen this error? “ERROR 1040 (00000): Too many connections.” If you’re working with MySQL long enough you surely have. This is quite a nasty error as it might cause complete downtime… transient errors with successful transactions mixed with failing ones as well as only some processes stopping to run properly causing various kinds of effects if not monitored properly.

There are number of causes for running out of connections, the most common ones involving when the Web/App server is creating unexpectedly large numbers of connections due to a miss-configuration or some script/application leaking connections or creating too many connections in error.

The solution I see some people employ is just to increase

  [Read more...]
MySQL Cluster latest developments – webinar replay + Q&A
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I recently hosted hosting a webinar which explained what MySQL Clusrter is, what it can deliver and what the latest developments were. The “Discover the latest MySQL Cluster Developments” webinar is now available to view here (http://www.mysql.com/news-and-events/web-seminars/discover-the-latest-mysql-cluster-developments/" target="_blank). At the end of this article you’ll find a full transcript of the Q&A from the live session.

Details:

View this webinar to learn how MySQL Cluster 7.3, the latest GA release, enables developer agility by

  [Read more...]
Orchestrator 1.0.4 released
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Outbrain's orchestrator Version 1.0.4 is released.

Quick links: Orchestrator Manual, FAQ, Downloads

What's new?

Co-masters

orchestrator now does a much better visualization of Master-Master replication:

  [Read more...]
Galera Cluster using GTID: MySQL vs. MariaDB
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Using GTID to attach an asynchronous Slave sounds promising. Lets have a look at the two existing GTID implementations and their integration with Galera.

GTID@MariaDB

There is one GTID used by the cluster and every node increments the common seqno by itself. This works well as long all transactions are replicated by Galera (simplified InnoDB). Because Galera takes care of the Commit Order of the transactions on all nodes. So having identical GTID/seqno from the start there are no problems.

  node1> show global variables like 'gtid_binlog_pos';
  +-----------------+---------+
  | Variable_name   | Value   |
  +-----------------+---------+
  | gtid_binlog_pos | 0-1-504 |
  +-----------------+---------+

  node2> show global variables like 'gtid_binlog_pos';
  +-----------------+---------+
  |
  [Read more...]
MariadB Galera: Attaching an asynchronous Slave using GTID
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Galera the synchronous Master-Master replication is quite popular. It is used by Percona XtraDB Cluster, MariaDB Galera Cluster and even patched MySQL binaries exist. Quite often you want to add a slave to a Galera Cluster. This is going to work quite well. All you need is at least configure log_bin, log_slave_updates and server_id on the designated Masters and attach your Slave.

GTID@MariaDB

Even you can use traditional (non GTID) replication. Using non GTID replication is a hassle. As you need to search for the right offset on the new Master to attach your Slave on.

Using GTID promises to be easier. As you simply switch to the new Master and the replication framework finds the new position based on the GTiD automatically.

As a fact we have two GTID


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What I learned while migrating a customer MySQL installation to Amazon RDS
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Hi, I recently had the experience of assisting with a migration of a customer MySQL installation to Amazon RDS (Relational Database Service). Amazon RDS is a great platform for hosting your MySQL installation and offers the following list of pros and cons:

  • You can scale your CPU, IOPS, and storage space separately by using Amazon RDS. Otherwise you need to take downtime and upgrade physical components of a rack-mounted server.
  • Backups, software version patching, failure detection, and (some) recovery is automated with Amazon RDS.
  • You lose shell access to your DB instance
  • You lose SUPER privilege for regular users. Many SUPER-type statements and commands are provided for as a Stored Procedure.
  • It is easy to set up multiple read
  [Read more...]
Some MySQL security tips
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This is a brief list of security tips for MySQL. It is by no means complete.

  • Follow the sudo example. Don't let all you DBAs and Ops have the password for the root account. Have each and every one of them have their own personal super-duper account, with their own personal and private password. This makes it so easy when someone leaves the company. No need to change passwords, just to remove the employee's account.
  • Block root. Either remove it completely or forbid it from logging in. Yes, there's a way hack in MySQL to have a valid account blocked from logging in. One way of making this happen is via common_schema's sql_accounts. Here's how to block root account using common_schema:
  [Read more...]
Prewarm your EBS backed EC2 MySQL slaves
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This is the story of cold blocks and mismatched instances and how they will cause you pain and cost you money until you understand why.

Most of the clients that we support run on the Amazon cloud using either RDS or running MySQL on plain EC2 instances using (Provisioned IOPS) PIOPS EBS for data storage.

As expected the common architecture is running a master with one or more slaves handling the read traffic.

A common problem is that after the slaves are provisioned (normally created from an EBS snapshot) they lag badly due to slow IO performance.

Unfortunately what tends to be lost in the “speed of provisioning new resources” fetish is some limitations in terms of data persistence layer (EBS).

If you are using EBS and you have created the EBS volume from snapshot or created a new volume you have to pre-warm the EBS volume

  [Read more...]
HowTo: Using MySQL for Visual Studio in you first ASP.NET MVC Application with EF 6
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Last week it was released the RC version of MySQL for Visual Studio 1.2.2. In this blog post we'll be showing one of the new features in this release. And we will be doing a short demo about some of the first steps when starting to use MySQL with .NET applications.
Picking the right clustering for MySQL: Cloud-only services or flexible Tungsten clusters?
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As businesses head into the cloud, it is tempting to reach for the first product that offers to make database operation as simple as punching a few buttons on a menu.  However, there’s a big difference between firing up cloud database services such as Amazon RDS for testing or development and finding a solution that can handle hundreds of millions of transactions daily. This webinar explores how
MySQL Connector/Python v2.0.0 alpha
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A new major version of Connector/Python is available: v2.0.0 alpha has been been released and is available for download! As with any alpha-software, it’s probably not good to throw it in production just yet.

Our manual has the full change log but here’s an overview of most important changes for this relase.

Some incompatibilities

The world evolves, at least the software does, and Python is not different. I’m not as bold as the guys at Django who dropped support of Python v2.6 with the Django v1.7 release. I’m leaving it in because I’m nice.

  [Read more...]
Monitoring MySQL flow control in Percona XtraDB Cluster 5.6
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Monitoring flow control in a Galera cluster is very important. If you do not, you will not understand why writes may sometimes be stalled. Percona XtraDB Cluster 5.6 provides 2 status variables for such monitoring: wsrep_flow_control_paused and wsrep_flow_control_paused_ns. Which one should you use?

What is flow control?

Flow control does not exist with regular MySQL replication, but only with Galera replication. It is simply the mechanism nodes are using when they are not able to keep up with the write load: to keep replication synchronous, the node that is starting to lag instructs the other nodes that writes should be paused for some time so it does not get too far behind.

If you are not familiar with this notion, you

  [Read more...]
Putting MySQL Fabric to Use: July 30 webinar
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Martin and I have recently been blogging together about MySQL Fabric (http://www.mysql.com/products/enterprise/fabric.html) (in case you’ve missed this, you can find the first post of the series here), and on July 30th, we’re going to be presenting a webinar on this topic titled “Putting MySQL Fabric to Use.”

The focus of the webinar is to help you get started quickly on this technology, so

  [Read more...]
New webinar-on-demand: Geographically distributed multi-master MySQL clusters
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Global data access can greatly expand the reach of your business. Continuent Tungsten multi-site multi-master (MSMM) solutions enable applications to accept write traffic in multiple locations across on-premises and cloud providers. This includes the following important real-world use cases: Improve performance for globally distributed users registering hardware devices by permitting updates
DBaaS, OpenStack and Trove 101: Introduction to the basics
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We’ll be publishing a series of posts on OpenStack and Trove over the next few weeks, diving into their usage and purpose. For readers who are already familiar with these technologies, there should be no doubt as to why we are incredibly excited about them, but for those who aren’t, consider this a small introduction to the basics and concepts.

What is Database as a Service (DBaaS)?
In a nutshell, DBaaS – as it is frequently referred to – is a loose moniker to the concept of providing a managed cloud-based database environment accessible by users, applications or developers. Its aim is to provide a full-fledged database environment, while minimizing the administrative turmoil and pains of managing the surrounding infrastructure.

Real life example: Imagine you are working


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MySQL Fabric – Part 1 – Installing
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Send to Kindle

MySQL Fabric is a tool included on MySQL Utilities that helps you to manage your MySQL instances.
It works by basically adding a new layer between your application and MySQL instances, which can provide an easy way to use sharding and build a high available system.

For More information about what is MySQL Fabric, please follow the documentation.

To install our Fabric environment, we will have to configure 4 servers, I will use the follow names and IP on this tutorial:

fabric1 (192.168.0.200) - fabric
mysql1 (192.168.0.201) - mysql master
mysql2 (192.168.0.202) - mysql slave
mysql3 (192.168.0.203) - mysql slave

Note: I’m running CentOS


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Showing all available MySQL data types when creating a new table with MySQL for Excel
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In this blog post we are going to talk about one of the features included since MySQL for Excel 1.3.0, a new advanced option was added to the Export Data dialog to show all available MySQL data types on its Data Type combo-box to override its default behavior that shows only the most commonly used data types.

Remember you can install the latest GA or maintenance version using the MySQL Installer or optionally you can download directly any GA or non-GA version from the MySQL Developer Zone.

Why TokuDB hates Transparent HugePages
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If you try to install the TokuDB storage engine on a modern Linux distribution it might fail with following error message:

2014-07-17 19:02:55 13865 [ERROR] TokuDB will not run with transparent huge pages enabled.
2014-07-17 19:02:55 13865 [ERROR] Please disable them to continue.
2014-07-17 19:02:55 13865 [ERROR] (echo never > /sys/kernel/mm/transparent_hugepage/enabled)

You might be curious why TokuDB refuses to start with Transparent HugePages. Are they not a good thing… allowing smaller kernel page tables and less TLB misses when accessing data in the buffer pool? I was curious, so I asked Tim Callaghan this very question.

This problem originates with TokuDB using jemalloc memory allocator, which uses a particular trick to deal with memory fragmentation. The classical problem with memory



  [Read more...]
Showing entries 1 to 30 of 16152 Next 30 Older Entries

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