There are times when what you have is a partially running database and a bunch of backup innodb tablespace files (the .ibd files). If you're using innodb_file_per_table, then you have a separate .ibd file for each InnoDB table.

Now, you have your running database with a bunch of tables, and you want to replace some of them with the backup .ibd files. According to the MySQL docs, you'd do this:

1. ALTER TABLE foo DISCARD TABLESPACE; (this deletes the current .ibd file)
2. copy the old .ibd file into your database directory
3. ALTER TABLE foo IMPORT TABLESPACE;
   

Assuming your .ibd file was from the same database and you did not drop the table and recreate it sometime between when you made the backup .ibd and now, this should work. Except... if …

I’m pleased to announce the first release of Kontrollcomm – “The Server Command Automation Interface” is a web-based application that automates remote command execution on linux and unix based servers. There are three main areas of the application: Hosts, Templates, and Commands. The use is very simple: all of your hosts are setup in the [...]

Its been a while anyone talked about Intel’s Hyper-Threading performance when it comes to databases. There were enough posts about disabling Hyper-Threading  completely when it comes to MySQL/InnoDB workloads way back when we had enough issues with scalability of InnoDB on multi-core systems. But things has changed quite a bit in the fast year or [...]

I finally got some free time to write up this new tech paper on how to migrate the parts of your MySQL databases that make sense to InfiniDB.  For those of you already familiar with InfiniDB, you can skip past the front 'why migrate' sections and go right to the "Migration Strategies" part that covers some general procedures and then goes on to give examples of various migration approaches.  And no, there is no registration on the site needed to get this paper.

If you find anRead More...

Introduction

If your WordPress comment counts got messed up, whether because of a plugin (I'm talking about you, DISQUS) or you messed with your database manually and did something wrong (yup, that's what I just did), fear not – I have a solution for you.

But first, a little background.

Comment Counts In WordPress

Here's how comment counts work in WP:

• Posts live in a table called wp_posts and each has an ID.
• Comments reside in a table called wp_comments, each referring to an ID in wp_posts.
• However, to make queries faster, the comment count is also cached in the wp_posts table, rather than getting calculated on every page load.
  If this count ever gets out of sync with the actual number of comments for some reason, WordPress, while still displaying all comments properly, will simply show the wrong count. …

I will be presenting Galera replication in O'Reilly MySQL Conference & Expo on April 14. Here is the link to the presentation abstract:
Galera - Synchronous Multi-master Replication For InnoDB.
The presentation will be run jointly with Alexey Yurchenko and will focus mostly in the practicalities of managing Galera cluster, like:

• 
  
• Howto download and install MySQL/Galera cluster
  
• Configuration options, clustering use cases and topologies
  
• Managing Galera cluster, joining node(s) in cluster, backups etc...
  
• Application connectivity options
  
• Monitoring Galera cluster, troubleshooting best practices
  

This presentation will …

In Released and new coming features I did not mentioned two additional INFORMATION_SCHEMA tables available in XtraDB:
It is

• INNODB_TABLE_STATS
• INNODB_INDEX_STATS

These table show statistics about InnoDB tables ( taken from InnoDB data dictionary).

INNODB_TABLE_STATS is

• | table_name | table name in InnoDB internal style ('database/table') |
• | rows | estimated number of all rows |
• | clust_size | cluster index (table/primary key) size in number of pages|
• | other_size | other index (non primary key) size in number of pages|
• | modified | internal counter to judge whether statistics recalculation should be done |

INNODB_INDEX_STATS is

• | table_name | table name in …

Finally, it is available for orders: The MySQL Admin Cookbook is the first book I have written and it is now ready for shipping. You can find more information about it at the publisher's website, including a free sample chapter!

I have yet to receive my sample copy, however that should not keep you from going ahead early and ordering it, e. g. from amazon.de. For your convenience, here is a direct link:

On Amazon you can also have a look at the index and a few pages of the first chapter.

More international points of sale can be found on the publisher's website, …

Yes, it's been a while. I did not blog for quite a long time. In April, I posted an article on MySQL on Solaris, and with that article I meant to go back to my regular blogging, i.e. writing an article every week or so. Soon after that article, I took responsibility of the European Presales team for Sun Software, Application Server Platform to be precise. APS included MySQL, the Identity Management software, SOA products, Glassfish and Java. This job was very similar to what I used to do between 1998 and 2002 and I was really excited to work with a large team again.
Now that we are part of Oracle, I am back to my original role MySQL, in the European Presales team, now called Sales Consulting.
It's really nice to be back. I really missed the excitement and the hands on that characterises the MySQL business. APS was a fantastic place to work and the incredibly talented people I've met are genuinely one of the best team I have ever worked …

So you're running the benchmark/stress test - how do you tell if MySQL server is really loaded ? This looks like the trivial question but in fact, especially when workload consists of simple queries I see the load generation and network really putting a lot less load on MySQL than expected. For example you may have 32 threads (or processes) running queries as fast as they can... does it really mean there is an 32 concurrent queries ran all the time ? It may be the case or it may be not...

Take a look at this server for example:

PLAIN TEXT CODE:

1. [root@db01 ~]# mysqladmin -i1  extended | grep Threads_running
2. | Threads_running                       | 1                    |
3. | Threads_running        …