In my previous post I explained how it could be possible to recover, on some specific cases, a single table from a full backup in order to save time and make the recovery process more straightforward. Now the scenario is worse because we don’t have a backup or the backup restore process doesn’t work. How [...]
The case for getting rid of duplicate “sets”
May 17, 2011 By 2 Comments
The most useful feature of the relational database is that it allows us to easily process data in sets, which can be much faster than processing it serially. When the relational database was first implemented, write-ahead-logging and other technologies did not exist. This made it difficult to implement the database in a way that matched [...]
Shard-Query EC2 images available
May 11, 2011 By 2 Comments
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 [...]
MySQL caching methods and tips
April 4, 2011 By 5 Comments
“The least expensive query is the query you never run.” Data access is expensive for your application. It often requires CPU, network and disk access, all of which can take a lot of time. Using less computing resources, particularly in the cloud, results in decreased overall operational costs, so caches provide real value by avoiding [...]
Using Flexviews – part one, introduction to materialized views
March 23, 2011 By 3 Comments
If you know me, then you probably have heard of Flexviews. If not, then it might not be familiar to you. I’m giving a talk on it at the MySQL 2011 CE, and I figured I should blog about it before then. For those unfamiliar, Flexviews enables you to create and maintain incrementally refreshable materialized [...]
How well does your table fits in innodb buffer pool ?
December 9, 2010 By 12 Comments
Understanding how well your tables and indexes fit to buffer pool are often very helpful to understand why some queries are IO bound and others not – it may be because the tables and indexes they are accessing are not in cache, for example being washed away by other queries. MySQL Server does not provide [...]
Data mart or data warehouse?
July 15, 2010 By 13 Comments
This is part two in my six part series on business intelligence, with a focus on OLAP analysis. Part 1 – Intro to OLAP Identifying the differences between a data warehouse and a data mart. (this post) Introduction to MDX and the kind of SQL which a ROLAP tool must generate to answer those queries. [...]
A workaround for the performance problems of TEMPTABLE views
May 19, 2010 By 7 Comments
MySQL supports two different algorithms for views: the MERGE algorithm and the TEMPTABLE algorithm. These two algorithms differ greatly. A view which uses the MERGE algorithm can merge filter conditions into the view query itself. This has significant performance advantages over TEMPTABLE views. A view which uses the TEMPTABLE algorithm will have to compute the [...]
Pacemaker, please meet NDB Cluster or using Pacemaker/Heartbeat to start a NDB Cluster
May 19, 2010 By 10 Comments
Customers have always asked me to make NDB Cluster starts automatically upon startup of the servers. For the ones who know NDB Cluster, it is tricky to make it starts automatically. I know at least 2 sets of scripts to manage NDB startup, ndb-initializer and from Johan configurator www.severalnines.com. If all the nodes come up [...]
Joining on range? Wrong!
May 17, 2010 By 10 Comments
The problem I am going to describe is likely to be around since the very beginning of MySQL, however unless you carefully analyse and profile your queries, it might easily go unnoticed. I used it as one of the examples in our talk given at phpDay.it conference last week to demonstrate some pitfalls one may [...]
