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Displaying posts with tag: innodb (reset)
Illustrating Primary Key models in InnoDB and their impact on disk usage

On a recent engagement I worked with a customer who makes extensive use of UUID() values for their Primary Key and stores it as char(36), and their row count on this example table has grown to over 1 billion rows.

The table is INSERT-only (no UPDATEs or DELETEs), and the bulk of their retrieval are PK lookups. Lookups by PK were performing acceptably, but they were concerned with the space usage by the table as we were approaching 1TB (running with innodb_file_per_table=1 and Percona Server 5.5).

This schema model presents an increasing burden for backups since they use Percona XtraBackup, and so the question was asked: does their choice of an effectively random Primary Key based on UUID() impact their on-disk storage, and to what extent? And as a neat trick I show towards the end of this post how you can calculate the …

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Using gdb to understand what locks (and when) are really set by InnoDB. Part I.

There is a story behind this post. To make it short, the detailed study presented here started when I noted old Bug #72748 in "No feedback" status few days ago. I considered this status totally wrong and started a discussion on Facebook about it (yes, this is what I usually do, I discuss handling of MySQL bugs in public).

The technical topic of this discussion (blaming aside) was the way AUTO-INC locks are set by InnoDB with default innodb_autoinc_lock_mode=1. Manual defines "bulk inserts" concept:

  • “Bulk inserts”
    Statements for which the number of rows to be inserted (and the number of required auto-increment values) is not known in …
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InnoDB 全文検索 : N-gram Parser

(この記事は InnoDB Full-Text : N-gram ParserYoshiaki Yamasaki が翻訳したものです)

私は今 …

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7 quick MySQL performance tips for the small business

We’ve heard lots in recent years about Big Data and the alternative models of data management and processing, like Hadoop and NoSQL. But truth be told, relational databases are still the workhorses of most of today’s small and medium sized businesses. Relational DBs date back over 40 years and SQL skills are fairly common, and they’re known to be highly secure.


MySQL is the world’s second most popular relational database management system (RDMS) and is the most popular open-source version of the database. It’s easily accessible and is often known to be part of the LAMP web development stack, standing for the ‘M’ in the acronym of popular tools, along with Linux, Apache, and PHP/Perl/Python. The fact that MySQL is free, easy to setup and scales fast are some of the main reasons why it’s the best match for many SMBs.


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Distributing innodb tables made simpler!

With the support for cloud backups in MEB, distributing innodb tables across multiple MySQL instances has become easier.

1. Backup - take a cloud(Amazon S3) backup of the tables to be shared using the --use-tts=with-full-locking option.

./mysqlbackup \
--host=localhost --user=mysqluser --protocol=TCP --port=3306 \
--cloud-service=s3 --cloud-aws-region=us-east-1 \
--cloud-bucket=mebbackup –cloud-object-key=items.img \
--cloud-access-key-id=<access-key> --cloud-secret-access-key=<secret-key> \
--include-tables=^mycompany\.items.* --use-tts=with-full-locking \
--backup-dir=/tmp/bkups/backupdir --compress --backup-image=- …

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InnoDB Full-Text: MeCab Parser

In addition to our general CJK support, as detailed in this blog post, we’ve also added a MeCab parser. MeCab is a Japanese morphological analyzer, and we now have a full-text plugin parser based on it!

How Would I Use It?

  1. Set the mecab_rc_file option — mecab_rc_file is a read-only system variable pertaining to the MeCab parser. The mecabrc file that it points to is a configuration file required by MeCab, …
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InnoDB Full-Text : N-gram Parser

The default InnoDB full-text parser is ideal for latin based languages where whitespace is the token or word separator, but for languages like Chinese, Japanese, and Korean (CJK)—where there is no fixed separators for individual words, and each word can be compromised of multiple characters—we need a different way to handle the word tokens. I’m now very happy to say that in MySQL 5.7.6 we’ve made use of the new pluggable full-text parser support in order to provide you with an n-gram parser that can be used with CJK!

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Deep dive into MySQL’s innochecksum tool

One of our Percona Support customers recently reported that Percona XtraBackup failed with a page corruption error on an InnoDB table. The customer thought it was a problem or bug in the Percona XtraBackup tool. After investigation we found that an InnoDB page was actually corrupted and a Percona XtraBackup tool caught the error as expected and hence the backup job failed.

I thought this would be an interesting topic and worthy of a blog post. In this article I will describe the innochecksum tool, when and how to use it and what are the possible fixes if an InnoDB table suffers from …

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Q&A: Multi-threaded Replication in MySQL 5.6 and MySQL 5.7

My webinar “Multi-threaded Replication in MySQL 5.6 and 5.7″ on February 25 generated several excellent questions following the presentation (available here for playback along with the slides). I didn’t have time to answer many of the questions during the session and so in this post I answer all of them. Thanks to everyone who attended!

Q: What do you expect from MTS with logical clock? Do you think performance would be good as with per database?
A: MTS with 5.6 is not usable if you have a single database. I do not have numbers, but this is quite frequent. With 5.7 everyone should be able to benefit from multi-threaded replication.

Q: When MySQL 5.6 was released, performance of MTS was lower, than in 5.5, for example. Is this addressed now?
A: I am not sure which …

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MySQL 5.7: InnoDB Intrinsic Tables


The MySQL Optimizer sometimes needs a temporary data-store during query processing, for storing intermediate results. Before MySQL 5.7, this need was serviced exclusively using a combination of the HEAP/MEMORY storage engine (for smaller tables) and the MyISAM storage engine (for larger tables). You can find more information on when disk based temporary tables (MyISAM or InnoDB) are used instead of MEMORY tables here.


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