Emphasis on clustering solutions comes up quite a lot when talking to customers about High Availability. The reason is because clustering is supposed to provide an easier solution for maintaining high availability and so that you do not have to rely on other tools and techniques outside of the database server. I thought it would be good to share the gist of many of my discussions around clustering, in the form of a blog post. So here I will be doing a high-level comparison between MySQL NDB Cluster and Percona XtraDB Cluster.

The post Percona XtraDB Cluster – A Drop-in-place Clustering Solution for MySQL appeared first on ovais.tariq.

Today when I was studying for the MySQL 5.6 exams.

I was studying for these two items:

• Create and utilize table partitioning

• Obtain MySQL metadata from INFORMATION_SCHEMA tables

The first step is to create a table, partition it with a hash.

mysql> CREATE TABLE pfoo (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255))
    -> PARTITION BY HASH(id) PARTITIONS 4;
Query OK, 0 rows affected (0.04 sec)

mysql> INSERT INTO pfoo(name) VALUES('test01'),('test02'),('test03'),('test04'),
    -> ('test05'),('test06'),('test07'),('test08'),('test09'),('test10'),('test11');
Query OK, 11 rows affected (0.00 sec)
Records: 11  Duplicates: 0  Warnings: 0

mysql> SELECT * FROM pfoo;
+----+--------+
| id | name   |
+----+--------+
|  4 | test04 |
|  8 | test08 |
|  1 | test01 |
|  5 | test05 …

Recently i had to manage big database installation that was running out of disk space. The partition on which the mysql datadir was located only had a few gigabytes free. Resizing the partition was not possible without a long downtime so that was no option. The installation had only innodb-tables so using symlinks was also not possible.

Luckily they were using MySQL 5.6 and the server had another partition with more than enough disk space available so i decided to use that partition for the biggest tables.

First get the 15 biggest tables:

root@mysqlserver [(none)]> set global innodb_stats_on_metadata=0; select table_schema, table_name "Table Name",round(sum(data_length+index_length)/1024/1024/1024,4) "Size (GB)" from information_schema.tables group by table_schema,table_name ORDER BY round(sum(data_length+index_length)) DESC LIMIT 15;
 Query OK, 0 rows affected (0.00 sec)
 …

Following on from my fun post on Where are they now: MySQL Storage Engines, I thought I’d cover the few storage engines that are really just interfaces to a collection of things. In this post, I’m talking about MERGE.

The MERGE engine was basically a multiplexer down to a number of MyISAM tables. They all had to be the same, there was no parallel query execution and it saw fairly limited use. One of the main benefits was that then you could actually put more rows in a MyISAM table than your “files up to 2/4GB” file system allowed. With the advent of partitioning, this really should have instantly gone away and been replaced by it. It wasn’t.

It is another MySQL feature that exists likely due to customer demand at the time. It’s not a complete solution by any means, PARTITIONING is way more complete and …

Download PDF Presentation

At the recent MySQL Tech Tour Events in New York and Boston I gave a presentation on MySQL integration with NoSQL,Big Data and the Cloud.

This covered discussion on topics including:

• Memcached API for InnoDB
• InnoDB Online Alter
• InnoDB Full Text Search (FTS)
• Partitioning inprovements for import/export
• SSD Optimisations
• Replication Improvements
• And much more …

As it's the end of the year it might be time to check your partition definitions.

If you forget to add a new partition in time partitions with no MAXVALUE might start to throw errors:

mysql> create table nye (`event_id` int not null auto_increment,`edate` year(4) not null, description varchar(200), 

    -> primary key(`event_id`,`edate`)) 

    -> partition by range( edate ) (

    -> partition p2010 VALUES LESS THAN (2011), 

    -> partition p2011 VALUES LESS THAN (2012), 

-> partition p2012 VALUES LESS THAN (2013) );
Query OK, 0 rows affected (0.04 sec)

mysql> INSERT INTO nye(edate,description) VALUES('2010','twenty ten'); 

Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO nye(edate,description) VALUES('2011','twenty eleven');

Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO …

A Pattern for a Newly Hired DBA? I don’t think this experience is unique. It has been shared repeatedly among those starting a job as a DBA (database administrator) at a new company, especially when the organization has never had a dedicated DBA. The conversation usually goes something like this: – “Welcome aboard <insert name here>! Here [...] …

On the 8/16 I conducted a webinar titled: "Scale Up vs. Scale Out" (http://www.slideshare.net/ScaleBase/scalebase-webinar-816-scaleup-vs-scaleout):


ScaleBase Webinar 8.16: ScaleUp vs. ScaleOut from ScaleBase
The webinar was successful, we had many attendees and great participation in questions and answers throughout the session and in the end. Only after the webinar it only occurred to me that one specific graphic was missing from the webinar deck. It was occurred to me after answering several audience questions about "the difference between …

Like others we were not satisfied with the fix for a bug in MySQL which caused the query cache and partitioning to not work reliably together. The bug, in simple terms, was that if the query cache was enabled and you used partitioned tables and if a partitioned table was using a transactional engine like InnoDB or XtraDB, the query cache could, under certain circumstances, return incorrect results.

Returning incorrect results is a definite, high-priority bug. However, the upstream fix was to disable all caching of queries from …

A customer opened an issue recently to ask why the query cache wasn't working after he upgraded to MySQL 5.5.25. The reason really ended up surprising me.

As of MySQL 5.5.23, the Query Cache is disabled for partitioned tables!

This is a "fix" for bug #53775.

At first I thought perhaps the fix for the bug had resulted in the query cache being inadvertently disabled for partitioned tables, but the comments that go along with the commit make it pretty clear that disabling the query cache was the intended "fix". You can review the commit message and the code changed at revision 2661.803.1 in the MySQL Server 5.5 repository.

…