Search Results for: search for data in row mysql

Optimizer hints in MySQL 5.7.7 – The missed manual

In version MySQL 5.7.7 Oracle presented a new promising feature: optimizer hints. However it did not publish any documentation about the hints. The only note which I found in the user manual about the hints is: It is now possible to provide hints to the optimizer by including /*+ … */ comments following the SELECT, […]

Checking table definition consistency with mysqldiff

Data inconsistencies in replication environments are a pretty common. There are lots of posts that explain how to fix those using pt-table-checksum and pt-table-sync. Usually we only care about the data but from time to time we receive this question in support: How can I check the table definition consistency between servers? Replication also allow […]

Yelp IT! A talk with 3 Yelp MySQL DBAs on Percona Live & more

Founded in 2004 to help people find great local businesses, Yelp has some 135 million monthly unique visitors. With those traffic volumes Yelp’s 300+ engineers are constantly working to keep things moving smoothly – and when you move that fast you learn many things. Fortunately for the global MySQL community, three Yelp DBAs will be […]

Choosing a good sharding key in MongoDB (and MySQL)

MongoDB 3.0 was recently released. Instead of focusing on what’s new – that is so easy to find, let’s rather talk about something that has not changed a lot since the early MongoDB days. This topic is sharding and most specifically: how to choose a good sharding key. Note that most of the discussion will also […]

Advanced JSON for MySQL

What is JSON JSON is an text based, human readable format for transmitting data between systems, for serializing objects and for storing document store data for documents that have different attributes/schema for each document. Popular document store databases use JSON (and the related BSON) for storing and transmitting data. Problems with JSON in MySQL It […]

Is MySQL’s innodb_file_per_table slowing you down?

MySQL’s innodb_file_per_table is a wonderful thing – most of the time. Having every table use its own .ibd file allows you to easily reclaim space when dropping or truncating tables. But in some use cases, it may cause significant performance issues. Many of you in the audience are responsible for running automated tests on your […]

‘Indexing’ JSON documents for efficient MySQL queries over JSON data

MySQL meets NoSQL with JSON UDF I recently got back from FOSDEM, in Brussels, Belgium. While I was there I got to see a great talk by Sveta Smirnova, about her MySQL 5.7 Labs release JSON UDF functions. It is important to note that while the UDF come in a 5.7 release it is absolutely […]

Looking deeper into InnoDB’s problem with many row versions

A few days ago I wrote about MySQL performance implications of InnoDB isolation modes and I touched briefly upon the bizarre performance regression I found with InnoDB handling a large amount of versions for a single row. Today I wanted to look a bit deeper into the problem, which I also filed as a bug. First […]

How small changes impact complex systems – MySQL example

If you’ve been studying complex systems you know what minor changes might cause consequences of much greater proportions, sometimes causing some effects that are not easily explained at first. I recently ran across a great illustration of such behavior while doing MySQL benchmarks which I thought would be interesting to share. I’m using a very […]

Sneak peek at the Percona Live MySQL Conference & Expo 2015

You know you’ll be there so why not save some $$ by registering now for the Percona Live MySQL Conference & Expo 2015 (April 13-16 in Santa Clara, Calif.). Super Saver registration discounts are available through Dec. 14 at 11:30 p.m. PST. (That’s just 10 days away!) What to expect this year? The Percona Live […]