We had discussion today which involved benchmarks of Join speed for MyISAM and Innodb storage engines for CPU bound workload, this is when data size is small enough to fit in memory and so buffer pool. I tested very simple table, having with about 20.000 rows in it on 32bit Linux. The columns “id” “i” […]
Gcache and IST The Gcache is a memory-based cache of recent Galera transactions that is local to each node in a cluster. If a node leaves and rejoins the cluster, it can use the gcache from another node that stayed in the cluster (i.e., its donor node) to fetch the transactions it missed (IST) as […]
I recently stumbled upon a post that Peter Zaitsev published back in 2007 titled “Innodb Performance Optimization Basics.” It’s a great post and reading it inspired me to examine what’s changed in the nearly six years that have followed in terms of MySQL, Percona Server – as well as in all of the other now-available […]
For people used to relational databases, using NoSQL solutions such as MongoDB brings interesting challenges. One of them is schema design: while in the relational world, normalization is a good way to start, how should we design our collections when creating a new MongoDB application? Let’s see with a simple example how we would create […]
On Friday I gave a presentation on “MySQL Query Patterns, Optimized” for Percona MySQL Webinars. 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 […]
I talk with lot of people who are really interested in Percona XtraDB Cluster (PXC) and mostly they are interested in PXC as a high-availability solution. But, what they tend not to think too much about is if moving from async to synchronous replication is right for their application or not. Facts about Galera replication […]
Innodb uses row level locks right ? So if you see locked tables reported in SHOW ENGINE INNODB STATUS you might be confused and rightfully so as Innodb table locking is a bit more complicated than traditional MyISAM table locks. Let me start with some examples. First lets run SELECT Query:
---TRANSACTION 12303, ACTIVE 26 sec
mysql tables in use 2, locked 0
MySQL thread id 53038, OS thread handle 0x7ff759b22700, query id 3918786 localhost root Sending data
select count(*) from sbtest,sbtest x
Trx read view will not see trx with id >= 12304, sees < 12301
As you can […]
It’s Friday again (already?) and as usual, we have a free ticket for Percona Live London. This time Tokutek is doing the honors of running the contest and selecting the winner. Instructions for entering the contest are on their blog, at the top of my recent guest post about covering indexes.
Infobright and InnoDB AMI images are now available There are now demonstration AMI images for Shard-Query. Each image comes pre-loaded with the data used in the previous Shard-Query blog post. The data in the each image is split into 20 “shards”. This blog post will refer to an EC2 instances as a node from here […]
This is the third in a series on whatâ€™s seriously limiting MySQL in certain circumstances (links: part 1, 2). This post is about subqueries, which in some cases execute outside-in instead of inside-out as users expect.