July 30, 2014

INSERT ON DUPLICATE KEY UPDATE and summary counters.

INSERT … ON DUPLICATE KEY UPDATE is very powerful but often forgotten MySQL feature. It was introduced in MySQL 4.1 but I still constantly see people unaware of it. Myself I like this feature big deal because it is designed in truly MySQL style – very efficient solution for freqent task while keeping it beautiful […]

Another reason why SQL_SLAVE_SKIP_COUNTER is bad in MySQL

It is everywhere in the world of MySQL that if your replication is broken because an event caused a duplicate key or a row was not found and it cannot be updated or deleted, then you can use ‘ STOP SLAVE; SET GLOBAL SQL_SLAVE_SKIP_COUNTER=1; START SLAVE; ‘ and be done with it. In some cases this is fine and you can repair the […]

Summertime Percona MySQL training update

Now that June has arrived it is time to plan what you will do over the summer months. In addition to your summer vacation plans, give thought to MySQL training for you and your team. Summer is the time to brush up on those critical skills needed to ensure all systems are ready for the holiday […]

MySQL Wish for 2013 – Better Memory Accounting

With Performance Schema improvements in MySQL 5.6 I think we’re in the good shape with insight on what is causing performance bottlenecks as well as where CPU resources are spent. (Performance Schema does not accounts CPU usage directly but it is something which can be relatively easily derived from wait and stage information). Where we’re […]

Timezone and pt-table-checksum

I recently worked through an issue with a client trying to detect data drift across some servers that were located in different timezones.  Unfortunately, several of the tables had timestamp fields and were set to a default value of CURRENT_TIMESTAMP.  From the manual, here is how MySQL handles timezone locality with timestamp fields: Values for TIMESTAMP columns are […]

Checking the subset sum set problem with set processing

Hi, Here is an easy way to run the subset sum check from SQL, which you can then distribute with Shard-Query:

Notice there is no 16 in the list. We did not pass the check. There are enough 15s though. The distinct value count for each item in the output set, must at least […]

Modeling MySQL Capacity by Measuring Resource Consumptions

There are many angles you can look at the system to predict in performance, the model baron has published for example is good for measuring scalability of the system as concurrency growths. In many cases however we’re facing a need to answer a question how much load a given system can handle when load is […]

Implementing efficient counters with MySQL

On many web sites you would see a counter how many time given object – blog post, forum thread, image, movie etc was viewed. This is sometimes handy feature but it can be rather expensive from performance point of view. The nasty thing with counters as they are implemented the most trivial way – they […]

What I learned while migrating a customer MySQL installation to Amazon RDS

Hi, I recently had the experience of assisting with a migration of a customer MySQL installation to Amazon RDS (Relational Database Service). Amazon RDS is a great platform for hosting your MySQL installation and offers the following list of pros and cons: You can scale your CPU, IOPS, and storage space separately by using Amazon […]

Managing shards of MySQL databases with MySQL Fabric

This is the fourth post in our MySQL Fabric series. In case you’re joining us now, we started with an introductory post, and then discussed High Availability (HA) using MySQL Fabric here (Part 1) and here (Part 2). Today we will talk about how MySQL Fabric can help you scale out MySQL databases with sharding. Introduction At the […]