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MySQL Fabric — Second Steps, er, Threads

MySQL Fabric will be used set up a three node High Availability server farm and this is the second part of a series. If you missed the last post, I will be doing a live demo (gulp!) on Fabric for the Triangle MySQL User Group in Raleigh. But part of the pain of live demos is how do you get multiple servers set up to make a server farm. E-I-E-I-oh?

Of course getting the slaves up on one laptop and running correctly is the biggest expenditure of time for this demo. For this I will use Vagrant. I am using Vagrant to set up three identical servers using VirtualBox to provide the servers I need for the demo. I am using Ubuntu.
sudo apt-get install vagrant VirtualBox
mkdir vagerant
cd vagrant
vagrant box add db1 …

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a multisource replication scenario: 10 masters, 1 slave.

A customer asked whether we they could have 10 or more masters consolidate all the data into a single central slave. After getting a bit more information from them and seeing the application functionality, it was clear that MySQL Labs 5.7.5 Multi Source Replication could be a good candidate. Why?:
– Each master is independent from the rest of the masters.
– One-way traffic: there is only one way to update a row, and that’s from the master.
– All the masters use the same schema and table, but no single master will ever need to, nor be able to update a row from another master.
– PK determined via app & master env.

Multisource replication is still in, but here’s what I did to test it out.

First, I read:

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MySQL 5.7 labs and the HTTP Plugin – inserting, updating and deleting records in MySQL via HTTP

In the MySQL Labs version of MySQL version 5.7, there is a new HTTP plugin. The HTTP plugin documentation from the labs site provides this information (from MySQL Labs):

The HTTP Plugin for MySQL adds HTTP(S) interfaces to MySQL. Clients can use the HTTP respectively HTTPS (SSL) protocol to query data stored in MySQL. The query language is SQL but other, simpler interfaces exist. All data is serialized as JSON. This version of MySQL Server HTTP Plugin is a Labs release, which means it’s at an early development stage. It contains several known bugs and limitation, and is meant primarily to give you a rough idea how this plugin will look some day. Likewise, the user API is anything but finalized. Be aware it will change in many respects.

In …

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Using Perl to send tweets stored in a MySQL database to twitter

Twitter is not my favorite social media site. Using twitter is like driving downtown, screaming what you want to say out the window, and hoping someone hears you. There might be tens of thousands of people downtown, but your message will only be heard by a few. Your best bet is to repeat your message as often as possible.

However, twitter is free and if you want to reach as many people (theoretically) as possible, you might as well use it. But sending tweets on a scheduled basis can be a pain. There are client programs available which allow you to schedule your tweets (Hootsuite is one I have used in the past). You can load your tweets in the morning, and have the application tweet for you all day long. But you still have to load the application with your tweets – one by one.

A friend of mine asked me if there was a way to send the same 200 tweets over and over again, spaced out every 20 minutes or so. He has a consulting …

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SYS Schema First Steps

Oracle DBAs have has the luxury of their V$ variables for a long time while we MySQL DBAs pretended we were not envious. With MySQL 5.6 and 5.7 we were gifted with the PERFORMANCE_SCHEMA tables. But there is such a wealth of information in those tables that it is intimidating to plunge in to them.  Thankfully Mark Leith has given us the SYS Schema. The SYS Schema is a collection of views, functions and procedures to help MySQL administrators get insight in to MySQL Database usage.

The first step is to get a copy of the SYS SCHEMA files.
git clone

Next install the SYS Schema (here for MySQL 5.7)
mysql -u root -p < ./sys_57.sql

Now run MySQL and look at this …

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mysqldump – 25 tips for DBAs

1) Is mysqldump text backup or binary backup
It is a text backup . If you open the backup file you will see all the statements that can be used to recreate databases and objects . It also has the insert statements to populate the tables with data

2) What is the syntax for mysqldump ?
mysqldump -u [uname] -p[pass] –databases [dbname][dbname2] > [backupfile.sql]

3) How to backup all databases using mysqldump ?
mysqldump -u root -p –all-databases > backupfile.sql

4) How to backup specific databases using mysqldump ?
mysqldump -u root -p –databases school hospital > backupfile.sql

5) How to backup specific tables using mysqldump ?
mysqldump –user=root –password=mypassword -h localhost databasename table_name_to_dump table_name_to_dump_2 > dump_only_two_tables_file.sql

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MySQL and swapping

Did you ever encounter swap space issue with MySQL ? This problem is really annoying and here are some possible solutions :

1) Track memory usage.. Try to identify the bottleneck using query below. It is not trivial job to zero in on the problem heap.. There are several temp tables being created at run time. Also estimating the OS cache being used by system MYISAM tables is not easy

SELECT ( @@key_buffer_size + @@query_cache_size + @@innodb_buffer_pool_size + @@innodb_additional_mem_pool_size + @@innodb_log_buffer_size + 80 * ( @@read_buffer_size + @@read_rnd_buffer_size + @@sort_buffer_size + @@join_buffer_size + @@binlog_cache_size + @@thread_stack + @@tmp_table_size ) ) / (1024 * 1024 * 1024) AS MAX_MEMORY_GB;

2) Configure the swappiness to 10 or 15.. By default it might be set at 60

cat /proc/sys/vm/swappiness will give the current swappiness value on your system

3) Set Numa interleaving to ON. …

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On Hadoop RDBMS. Interview with Monte Zweben.

“HBase and Hadoop are the only technologies proven to scale to dozens of petabytes on commodity servers, currently being used by companies such as Facebook, Twitter, Adobe and”–Monte Zweben.

Is it possible to turn Hadoop into a RDBMS? On this topic, I have interviewed Monte Zweben, Co-Founder and Chief Executive Officer of Splice Machine.


Q1. What are the main challenges of applications and operational analytics that support real-time, interactive queries on data updated in real-time for Big Data?

Monte Zweben: Let’s break down “real-time, interactive queries on data updated in real-time for Big Data”. “Real-time, interactive queries” means that results need to be returned in milliseconds to a few seconds.
For “Data updated in real-time” to happen, …

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XFS and EXT4 Testing Redux

In my concluded testing post, I declared EXT4 my winner vs XFS for my scenario. My coworker, @keyurdg, was unwilling to let XFS lose out and made a few observations:

  • XFS wasn’t *really* being formatted optimally for the RAID stripe size
  • XFS wasn’t being mounted with the inode64 option which means that all of the inodes are kept in the first 2TB. (Side note: inode64 option is default in newer kernels but not on CentOS 6’s 2.6.32)
  • Single threaded testing isn’t entirely accurate because …
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MySQL: The most popular open source database for WWW

(Note : This an Article from last year when MySQL5.6 was released)

While Database technology is one of the oldest branches of computer science, it remains a fundamental computer technology that continues to attract new research. The current focus of Databases technology is towards adapting hot new tends like multi-core chips, solid state devices, NOSQL and Cloud. So what does a contemporary internet developer look for in a database for the internet era? And why does MySQL remain the most popular database for the web?


For a database to be useful while developing products for the Web, the most important requirements are that it should be quick and easy to download, quick to set up, powerful enough to get the job done, be fast and flexible to use and finally be scalable on the newest hardware. Compatibility with the latest technologies like the cloud also remains foremost in the minds of …

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