An InnoDB table statistics is used for JOIN optimizations and helping the MySQL optimizer choose the appropriate index for a query. If a table’s statistics or index cardinality becomes outdated, you might see queries which previously performed well suddenly show up on slow query log until InnoDB again updates the statistics. But when does InnoDB perform the updates aside from the first opening of the table or manually running ANALYZE TABLE on it? The 2 instances below are documented from the MySQL and InnoDB plugin’s manual:

1. Metadata commands like SHOW INDEX, SHOW TABLE STATUS and SHOW [FULL] TABLES (or their corresponding queries from INFORMATION_SCHEMA.TABLES and INFORMATION_SCHEMA.STATISTICS)
2. When 1 / 16th of the table or 2Billion rows has been modified, whichever comes first. ./row/row0mysql.c:row_update_statistics_if_needed

…

I’ve been seeing a few occasions where Neil J. Gunther’s Universal Scalability Law doesn’t seem to model all of the important factors in a system as it scales. Models are only models, and they’re not the whole truth, so they never match reality perfectly. But there appear to be a small number of cases where systems can actually scale a bit better than linearly over a portion of the domain, due to what I’ve been calling an “economy of scale.” I believe that the Universal Scalability Law might need a third factor (seriality, coherency, and the new factor, economy of scale). I don’t think that the results I’m seeing can be modeled adequately with only two parameters.

Here are two publicly available cases that appear to demonstrate this phenomenon: Robert Haas’s recent blog post on PostgreSQL, titled …

70x Higher Performance, Cross Data Center Scalability and New NoSQL Interface

Its been an exciting week for all involved with MySQL Cluster, with the announcement of the second Development Milestone Release (7.2.1) at Oracle Open World. Highlights include:

- Enabling next generation web services: 70x higher complex query performance, native memcached API and integration with the latest MySQL 5.5 server

- Enhancing cross data scalability: new multi-site clustering and enhanced active/active replication

- Simplified provisioning: consolidated user privileges.

You can download the DMR for evaluation now from: http://dev.mysql.com/downloads/cluster/ (select Development Milestone Release tab).

You …

MySQL @ #OOW11 is complete and we finished off with a very interactive session with Karthikeyan from NetApp. This was the most interactive session I had seen @ #OOW this year.

Some topics covered included:

• NetApp : 
  • Deduplication
    • 30% to 40% space savings for MySQL on NetApp
  •  Snapshot and instant point in time data copies with minimal storage space
    • ONLINE MYSQL BACKUP USING NETAPP SNAPSHOT TECHNOLOGY 
  •   …

This year’s Surge conference was a great sophomore event to follow up last year’s inaugural conference. A lot of very smart people were there, and the hallway track was great.

I presented on three things: a lightning talk about causes of MySQL downtime; I chaired a panel on Big Data and the Cloud; and I showed how to derive scalability and performance metrics from TCP traffic. I’ve sent my slides to the Surge organizers, and I understand that they will be posting them as well as integrating them into the video of my session. In the meanwhile you can download my slides from Percona’s presentations page.

Further Reading:

• I’m speaking at Surge 2011
…

Oracle's turn-about announcement of a NoSQL product wasn't really surprising. When Oracle spends time and effort putting down a technology, you can bet that its secretly impressed, and trying to re-implement it in its back room. So Oracle's paper "Debunking the NoSQL Hype" should really have been read as a backhanded product announcement. (By the way, don't click that link; the paper appears to have been taken down. Surprise.)

I have to agree with DataStax and other developers in the NoSQL movement: Oracle's announcement is a …

The last day of #OOW is here and MySQL events continue. Even after the big Sting concert last night. I am now sitting in a MySQL Crash Course talk given by Alexander Nozdrin and Dmitry Lenev. The room is packed (~100) ! A poll of the room  showed that the majority here are all new to MySQL. Very encouraging to see the MySQL community growing !

This has been an amazing week in San Francisco with 45,000 new friends. The MySQL tracks have been warmly received by both the MySQL core in attendance and the Oracle family with its many branches. A special thanks to Sheeri Cabral and Sarah Novotny for their organization of two tracks of Community session on Sunday and their great presentations in the MySQL Database track. It has been a long week filled with all technical levels of presentations, product announcements, and meeting a lot of folks who use MySQL but are just joining our community.

So we start off Thursday with two sessions: NoSQL Interfaces to MySQL Cluster in Goldengate C1 at 9AM and What Causes Downtime in MySQL, and How Can You Prevent It next door at Goldengate C2 (all sessions in the Marriott)

Then we have the following in C2: MySQL Crash Course: Overview of Basic MySQL Concepts at 10:30, MySQL …

I remember my first computer. It was a TI-99/4A. I bought it back in 1982 (I think), and it cost around $300. The entire computer fit inside what looked like a really thick keyboard. It had a slot on the right for cartridges, and I had a cassette tape drive that I used for backing up the BASIC computer programs that I wrote. I thought that it was a great computer at the time, but I really didn’t have anything to compare it to. The games were the best part of the computer (really the only fun part – my BASIC skills were lacking). And even though the games were fairly lame by even 1982 standards, but they were still plenty of fun to play.

I also remember when I saw a Macintosh for the first time. I had followed Apple for some time, but I had never had the opportunity to actually see a Macintosh. I think it was in 1987 or 1988, when I was a student at the University of Georgia. I believe it was a Mac SE, and it had one megabyte of RAM and a …

My team was provisioning a ruby on rails application on a new Operating System with different ruby and client libraries and we came across a strange bug.

Intermittently we were seeing the failures in the application with the following messages in the passenger log:

NoMethodError: undefined method `each' for nil:NilClass

and

(NoMethodError) "undefined method `each' for nil:NilClass"

/usr/local/rvm/gems/ruby-1.9.2-p0/ruby/1.9.1/gems/mysql2-0.2.4/lib/active_record/connection_adapters/mysql2_adapter.rb:628:in `select'
/usr/local/rvm/gems/ruby-1.9.2-p0/ruby/1.9.1/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `select_all'
/usr/local/rvm/gems/ruby-1.9.2-p0/ruby/1.9.1/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract/query_cache.rb:54:in `block in select_all' …