April 18, 2014

INSERT ON DUPLICATE KEY UPDATE and REPLACE INTO

Jonathan Haddad writes about REPLACE INTO and INSERT ON DUPLICATE KEY UPDATE. Really, Why MySQL has both of these, especially both are non ANSI SQL extensions ? The story here seems to be the following – REPLACE INTO existed forever, at least since MySQL 3.22 and was a way to do replace faster and what […]

Duplicate indexes and redundant indexes

About every second application I look at has some tables which have redundant or duplicate indexes so its the time to speak about these a bit. So what is duplicate index ? This is when table has multiple indexes defined on the same columns. Sometimes it is indexes with different names, sometimes it is different […]

Percona Toolkit 2.1.11 is now available

Percona is glad to announce the release of Percona Toolkit 2.1.11 on March 4th, 2013 (Downloads are available here). Bugs Fixed: Fixed bug 1279502: –version-check behaves like spyware The configuration for what information Percona Toolkit should retrieve is not hard-coded in the scripts. Instead, it is downloaded from v.percona.com. One of the possible parameters was the name […]

The ARCHIVE Storage Engine – does it do what you expect?

Sometimes there is a need for keeping large amounts of old, rarely used data without investing too much on expensive storage. Very often such data doesn’t need to be updated anymore, or the intent is to leave it untouched. I sometimes wonder what I should really suggest to our Support customers. For this purpose, the […]

How can we bring query to the data?

Baron recently wrote about sending the query to the data looking at distributed systems like Cassandra. I want to take a look at more simple systems like MySQL and see how we’re doing in this space. It is obvious getting computations as closer to the data as possible is the most efficient as we will […]

How InnoDB promotes UNIQUE constraints

The other day I was running pt-duplicate-key-checker on behalf of a customer and noticed some peculiar recommendations on an InnoDB table with an odd structure (no PRIMARY key, but multiple UNIQUE constraints). This got me thinking about how InnoDB promotes UNIQUE constraints to the role of PRIMARY KEYs. The documentation is pretty clear: [DOCS] When […]

Benchmarking Percona Server TokuDB vs InnoDB

After compiling Percona Server with TokuDB, of course I wanted to compare InnoDB performance vs TokuDB. I have a particular workload I’m interested in testing – it is an insert-intensive workload (which is TokuDB’s strong suit) with some roll-up aggregation, which should produce updates in-place (I will use INSERT .. ON DUPLICATE KEY UPDATE statements […]

Percona Toolkit 2.1.9 is ready

About a month ago, we held a bug raffle for Percona Toolkit 2.1.9.  The turnout was good and the resulting release is worth upgrading to, especially if you were affected by the backwards-incompatible changes to pt-heartbeat in 2.1.8.  Here are the release notes for Percona Toolkit 2.1.9 which highlight the bugs fixed: Percona Toolkit 2.1.9 has been released. […]

Concatenating MyISAM files

Recently, I found myself involved in the migration of a large read-only InnoDB database to MyISAM (eventually packed). The only issue was that for one of the table, we were talking of 5 TB of data, 23B rows. Not small… I calculated that with something like insert into MyISAM_table… select * from Innodb_table… would take […]

Edge-case behavior of INSERT…ODKU

A few weeks back, I was working on a customer issue wherein they were observing database performance that dropped through the floor (to the point of an outage) roughly every 4 weeks or so. Nothing special about the environment, the hardware, or the queries; really, the majority of the database was a single table with […]