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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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MySQL 5.7.5- More variables in replication performance_schema tables

At MySQL, replication usability is of utmost importance to us. Replication information has long been part of SHOW commands, SHOW SLAVE STATUS occupying a major chunk of it. The other sources of replication information being:


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MySQL 5.7.5-labs: Multi-source Replication

Multi-source replication for MySQL has been released as a part of 5.7.5-labs-preview
downloadable from It is one among the several features that are
cooking in the replication technologies at MySQL.  (For a birds eye view of all
replication features introduced in 5.7 and labs, look  at the blog posts here and here.

Previously, we have introduced a preliminary multi-source feature labs preview. Based on the feed back from that labs release, we …

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Slow query log – Confusing information in manuals

Below is the excerpt from MySQL manuals on slow query log :

“By default, administrative statements are not logged, nor are queries that do not use indexes for lookups. This behavior can be changed using log_slow_admin_statements and log_queries_not_using_indexes, as described later. “

This manual entry is kind of misleading . It means that queries not using indexes are not logged by default. Let us see what the reality is :

1) Let us see if queries not using indexes are being logged.

Below table does not have index:

mysql> describe employee ;
| Field | Type    | Null | Key | Default | Extra |
| ID    | int(11) | YES  |     | NULL    |       |
1 row in set (0.00 sec)

mysql> show indexes from employee ;
Empty set (0.00 sec) …
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High-Availability at MySQL Central

This year’s MySQL Central at Oracle Open World was an exhilarating experience. In contrast to the previous year’s MySQL Connect events, MySQL have now got their own Central at the main Oracle Open World. In the previous years, we were always short on time and trying to get a lot of sessions into just two days was just to much. This time I could both present sessions, attend sessions by other users, and also to talk to people in the MySQL community: something that I really enjoy and also find very valuable to see where we should be heading.

This year, the “MySQL Fabric Team” representation on MySQL Central was me and Narayanan Venkateswaran, which is heading the sharding solution in MySQL Fabric. Together with the conference, we also released MySQL Fabric 1.5.2 as the GA release of MySQL Fabric 1.5 containing a few new features:

  • Server …
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