Sarah Sproehnle's Blog (9)

I recently gave a talk about importing and exporting data between MySQL and Hadoop at Oracle Open World.  Here are the slides for that talk:

MySQLandHadoopNov2011.pdf

There's a lot of buzz lately about Hadoop. If you're completely new to Hadoop, I recommend the free videos from Cloudera (http://www.cloudera.com/resources/?type=Training). If you have a vague idea and want to play around, it's easy! Continue

I'll be giving 2 talks this year. Here's a quick description:





Want Faster Queries?

Fixing slow queries is often very easy if you know what to look for and it can give huge performance gains. In this talk I'll cover common SQL mistakes, how to identify "bad" queries, indexing techniques, using EXPLAIN to verify execution plan, etc.…





Continue

Over and over I see customers that don't understand what int(11) really means. Their confusion is understandable. Many know what defining a char(10) means (a fixed-sized character string that allows up to 10 characters). However, ints are different.



First of all, there are 5 types of integer. They are all fixed size.

Type

# of…

Continue

For easy MySQL failover, replication is a great solution. This post will cover the basics of performing a failover in case your master dies.

First, setup one-way replication (or two-way, but don't plan to use both servers for writes at the same time). Next, you'll want to direct all activity, or at least the writes, to the master. If the master dies, there are two major concerns:

1. Redirecting the clients to the slave. There are several ways to handle this, such as…

Continue

This post describes how MySQL Cluster executes queries. First of all, Cluster is a storage engine. It doesn't actually execute queries because it doesn't speak SQL. That is why you use a MySQL server, which parses your queries and sends low-level storage engine API calls to the Cluster data nodes. The data nodes know how to retrieve or store data. Or you can talk to the data nodes directly using the NDB API(s).



MySQL Cluster has various means of executing queries. They boil down… Continue

After Chris' great post, What's faster than ALTER, I got thinking about REPAIR. REPAIR TABLE can be slow, but may seem necessary if your table is corrupt.



A little background:

MyISAM tables are prone to corruption if they are receiving updates/inserts/deletes/etc and your server crashes. Doing a REPAIR TABLE can generally "fix" them, but it can take time. The larger the table,… Continue

There is thorough documentation about the Partitioning feature in MySQL 5.1. There are also nice articles like this one by Robin. However, I thought it would be useful to have a quick "how-to" guide to partitioning by dates. I'll use the world schema to keep it easy.



Partitioning a… Continue

MySQL replication is a great feature: it's easy to setup and relatively easy to manage, it can provide scalabilty and availability, a master can serve dozens of slaves, etc. However, sometimes people have the problem that the slaves can't keep up; they get further and further behind, which is a major problem. So this post talks about why that happens (sometimes) and what you can do about it.



Causes:

• The most common reason that a slave cannot keep up with the…

Continue