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Displaying posts with tag: myisam (reset)
Fun with Bugs #47 - On Some Bugs Found Using oprofile

Users had to identify the reasons for MySQL performance problems somehow well before famous Performance Schema appeared in MySQL 5.5.3, and even before Domas invented his Poor Man's Profiler. Poor users had to use some OS-level tools, and among these tools the most important one was, probably, oprofile.

oprofile is a system-wide statistical profiling tool for Linux available since 2001 and 2.4.x kernels. It was applied to MySQL for many …

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MySQL 8.0: The end of MyISAM

This blog discusses the gradual end of MyISAM in MySQL.

The story that started 20 years ago is coming to its end. I’m talking about the old MyISAM storage engine that was the only storage provided by MySQL in 1995, and was available in MySQL for 20+ years. Actually, part of my job as a MySQL consultant for 10+ years was to discover MyISAM tables and advise customers how to convert those to InnoDB.

(Check your MySQL installation, you may still have MyISAM tables).

MySQL 5.7 still used MyISAM storage for the system tables in the MySQL schema.

In MySQL 8.0 (DMR version as of writing), the MyISAM storage engine is still available. But in a very limited scope:

  • After …
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Q: Does MySQL support ACID? A: Yes

I was recently asked this question by an experienced academic at the NY Oracle Users Group event I presented at.

Does MySQL support ACID? (ACID is a set of properties essential for a relational database to perform transactions, i.e. a discrete unit of work.)

Yes, MySQL fully supports ACID, that is Atomicity, Consistency, Isolation and Duration. (*)

This is contrary to the first Google response found searching this question which for reference states “The standard table handler for MySQL is not ACID compliant because it doesn’t support consistency, isolation, or durability”.

The question is however not a simple Yes/No because it depends on timing …

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corrupted / crashed MyISAM + mysql_repair_threads = stuck “Repair with N threads”

This post explains on the usage of mysql_repair_threads for repairing myisam table & the processlist status Repair with N threads

Test your knowledge: Percona XtraDB Cluster (PXC) quiz

I often talk with people who are very interested in the features of Percona XtraDB Cluster (PXC) such as synchronous and parallel replication, multi-node writing and high availability. However some get confused when operating a real PXC cluster because they do not fully realize the implications of these features. So here is a fun way to test your PXC knowledge: try to solve these 12 questions related to PXC! (you will find the answers at the end of the post.)


1. With Galera 3.x, support for MyISAM is experimental. When can we expect to have full MyISAM support?
a. This will never happen as Galera is designed for transactional storage engines.
b. This is planned for Galera 4.0.

2. Why aren’t all workloads a good fit for PXC?
a. Execution plans can change compared to a regular MySQL server, so performance is sometimes not as good as with a regular MySQL server.
b. Large …

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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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MySQL Admin 101 for System Admins – key_buffer_size

As discussed in my presentation to NYLUG, I wanted to provide system administrations with some really quick analysis and performance fixes if you had limited knowledge of MySQL.

One of the most important things with MySQL is to tune memory properly. This can be complex as there are global buffers, and per session buffers, memory tables, and differences between storage engines. Even this first tip has conditions.

Configuration of MySQL can be found in the my.cnf file (How can I find that). Some variables are dynamic and some are not, and these can change between versions. Check out The most important MySQL Reference Manual page that everybody should bookmark …

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Regarding MySQL 5.6 temporary tables format

default_tmp_storage_engine variable was introduced in 5.6.3, allowing the configuration of the default engine for temporary tables. This seems to be in the direction, as I commented before, of making MyISAM an optional engine. In 5.7, a separate tablespace is being created to hold those tables in order to reduce its performance penalty (those tables do not need to be redone if the server crashes, so extra writes are avoided).

However, I have seen many people assuming that because default_tmp_storage_engine has the value “InnoDB”, all temporary tables are created in InnoDB format in 5.6. This is not true: first, because implicit temporary tables are still being created in memory using …

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MySQL 5.6 Full Text Search Throwdown: Webinar Q&A

Yesterday (Oct. 22) I gave a presentation titled “MySQL 5.6 Full Text Search Throwdown.” If you missed it, you can still register to view the recording and my slides.

Thanks to everyone who attended, and especially to folks who asked the great questions. I answered as many as we had time for during the session, but here are all the questions with my complete answers:

Q: Does Solr automatically maintain its index against MySQL? Do you have to hit the Solr server with a specific query to keep the index ‘warm’?

There are several strategies for updating a Solr …

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Testing the Fastest Way to Import a Table into MySQL (and some interesting 5.7 performance results)

As I mentioned on my last post, where I compared the default configurations options in 5.6 and 5.7, I have been doing some testing for a particular load in several versions of MySQL. What I have been checking is different ways to load a CSV file (the same file I used for testing the compression tools) into MySQL. For those seasoned MySQL DBAs and programmers, you probably know the answer, so you can jump over to my 5.6 versus 5.7 results. However, the first part of this post is dedicated for developers and MySQL beginners that want to know the answer to the title question, in a step-by-step fashion. I must say I also learned something, as I under- and over-estimated some of the effects of certain …

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