Note: this article was originally published on http://blogs.innodb.com on Dec 20, 2011 by Jimmy Yang.

InnoDB full-text search (FTS) is finally available in MySQL 5.6.4 release. The feature has been on trial through MySQL’s summer lab release, thus we had several blogs covering the feature. In this blog, we will leave the “how to” part of the feature to those blogs, and focus on some important characteristics of this new feature, so you will have a better understanding when trying on the feature.

The InnoDB Full-text Index as an Inverted Index

When comes to the basic design, InnoDB takes a traditional way to implementation the full-text index, which is a so called “Inverted Index”. It composes of a set of auxiliary “index tables” that stores the “Word” “Doc ID” pair, as well as each word’s position in the original …

Note: this article was originally published on http://blogs.innodb.com on Dec 20, 2011 by Kevin Lewis.

In the 5.6.4 release it is now possible to create an InnoDB database with 4k or 8k page sizes in addition to the original 16k page size. Previously, it could be done by recompiling the engine with a different value for UNIV_PAGE_SIZE_SHIFT and UNIV_PAGE_SIZE. With this release, you can set –innodb-page-size=n when starting mysqld, or put innodb_page_size=n in the configuration file in the [mysqld] section where n can be 4k, 8k, 16k, or 4096, 8192, 16384.

The support of smaller page sizes may be useful for certain storage media such as SSDs. Performance results can vary depending on your data schema, record size, and read/write ratio. But this provides you more options to optimize your performance.

When this new setting is used, the page size is set …

Recently I found in a forum the following request for help:

My MySQL instance crashed because of free disk space fault. I saw in /var/lib/mysql all the files: ibdata1, ib_logfile* and all the folders containing frm files. Well, when i solved the problem and run successfully the instance, some databases disappeared. One of those is the most important, and i don't know how many tables had and their structures. Is there any way for recover the entire lost database (structure and data) only having the ibdata1 file?

First of all the observation sounds a bit strange because files do not just disappear. So I fear that its not just the .frm files which are lost. But let's think positive and assume just the .frm files have gone...

To recover …

Recently I found in a forum the following request for help:

My MySQL instance crashed because of free disk space fault. I saw in /var/lib/mysql all the files: ibdata1, ib_logfile* and all the folders containing frm files. Well, when i solved the problem and run successfully the instance, some databases disappeared. One of those is the most important, and i don't know how many tables had and their structures. Is there any way for recover the entire lost database (structure and data) only having the ibdata1 file?

First of all the observation sounds a bit strange because files do not just disappear. So I fear that its not just the .frm files which are lost. But let's think positive and assume just the .frm files have gone...

To recover …

Not to be outdone by Vadim’s announcement, I also have one: Percona Toolkit’s manual is now available as PDF (requires registration). You can get it here: http://www.percona.com/software/percona-toolkit/

Thanks to Mauricio Stekl, who did all the hard work to create the PDF of the manual — and did it fast, too.

For years (12+) I have been building systems on every tier of the web. Everything from low-level OS optimizations, mySQL internals, interpreted language performance tricks to static content optimization.

Building CDN's are easy, but what makes Akami or Cloudfront attractive-presences known as edge nodes-they have around the world to syndicate your content closest to the requester. 
Their smart DNS servers send people to the closest edge node to serve content. This is great for serving Javascript, Images CSS (Video) because its static. 
Here is a good example. Your system can serve content in less then 5ms if the network is not involved. With the network overhead that content is served in 10ms time if you are close to the DC (say about 1200 miles). Yet your users on the east coast (assuming your dc is in the west coast) or better yet your users in Europe see this content in 355 ms. Around 300 ms or …

If a DBA needs to reset the mysql root password – one method of doing this is to run mysqld with -skip-grant-tables as a command line parameter. This is a bad practice for many reasons and as a DBA friend of mine says – it’s a lot like locking your door with the window open. If you are using mysql for especially secure data you should consider your options.

One option, and likely preferred, is to replace the default mysql from various sources with one built with this feature disabled – see http://dev.mysql.com/doc/refman/5.1/en/source-configuration-options.html#option_configure_disable-grant-options

I am not aware of any distro’s that are built with this option – but seems like a fair number of folks out there would appreciate having a build like this.

But …

Last month we did a few improvements in InnoDB memory usage. We solved a challenging issue about how InnoDB uses memory in certain places of the code.

The symptom of the issue was that under a certain workloads the memory used by InnoDB kept growing infinitely, until OOM killer kicked in. It looked like a memory leak, but Valgrind wasn’t reporting any leaks and the issue was not reproducible on FreeBSD – it only happened on Linux (see Bug#57480). Especially the latest fact lead us to think that there is something in the InnoDB memory usage pattern that reveals a nasty side of the otherwise good-natured Linux’s memory manager.

It turned out to be an interesting …

The problem and its cause

There have been several complaints over the years about InnoDB’s inability to scale beyond 256 connections. One of the main issues behind this scalability bottleneck was the read view creation that is required for MVCC (Multi Version Concurrency Control) to work. When the user starts a transaction this is what InnoDB does under the hood:

• Create or reuse a transaction instance – usually it is reused, the transactions are reused from a pool (trx_sys_t::mysql_trx_list).
• Initialize the transaction start time and assign a rollback segment
• Append the transaction to an active  transaction list ordered on trx_t::id in descending order

The append to  the trx_sys_t::trx_list and corresponding remove during commit is covered by trx_sys_t::mutex. After the transaction is “started” and if the transaction has an isolation greater …

InnoDB full-text search (FTS) is finally available in MySQL 5.6.4 release. The feature has been on trial through MySQL’s summer lab release, thus we had several blogs covering the feature. In this blog, we will leave the “how to” part of the feature to those blogs, and focus on some important characteristics of this new feature, so you will have a better understanding when trying on the feature.

The InnoDB Full-text Index as an Inverted Index

When comes to the basic design, InnoDB takes a traditional way to implementation the full-text index, which is a so called “Inverted Index”. It composes of a set of auxiliary “index tables” that stores the “Word” “Doc ID” pair, as well as each word’s position in the original text.

Incoming text strings in the inserting records are extracted out, tokenized and decomposed into individual words, and such words are then inserted into the auxiliary …