Archive for the ‘mysql’ Category
Wednesday, April 23rd, 2008
I'm not sure how I didn't see this earlier, but it looks like MySQL 5.1 is coming with a load balancer for replicated servers. I'm absolutely pumped about this - we've got a few sites running with multiple db slaves and it's so annoying having to check if they're ...
Posted in mysql | 2 Comments »
Tuesday, April 1st, 2008
While I've known how floating points are stored, I didn't know if decimal was stored any differently, or if it was more or less accurate. According to a post on the MySQL list:
Bruno Rodrigues Silva wrote:
> Dear all.
>
> The MySQL Manual inform that Decimal Data Type is used
> ...
Posted in mysql | 1 Comment »
Wednesday, February 6th, 2008
I need to compile something and use the MySQL C++ library. I have mysql and mysql++ already compiled, I won't go over how to do that now.
I added the following code to the top of my source:
#include <mysql++.h>
I got an error
/Users/jhaddad/dev/search_engine/main.cpp:4:21: error: mysql++.h: No such file or directory
Not ...
Posted in c++, mac, mysql, tutorial, xcode | 3 Comments »
Tuesday, November 13th, 2007
I'm setting up my first mysql cluster, and just wanted some clarification on a few things.
In the manual, it says:
Online schema changes. It is not possible to make online schema changes such as those accomplished using ALTER TABLE or CREATE INDEX, as the NDB Cluster engine does not support ...
Posted in cluster, mysql | No Comments »
Wednesday, October 31st, 2007
We were using replication to deal with certain queries that were producing table scans. I realize this is not a great long term solution but we were migrating a web site that was set up this way, so it wasn't really a choice.
We had a database that was a ...
Posted in mysql, replication | No Comments »
Thursday, October 11th, 2007
MySQL query cache can be useful, if it works. Here's how to check it's effectiveness.
show status like 'qc%';
+-------------------------+----------+
| Variable_name | Value |
+-------------------------+----------+
| Qcache_free_blocks | 6407 |
| ...
Posted in mysql | No Comments »
Monday, June 11th, 2007
Let me first state that I've only run MySQL on Linux and MacOS X, never Windows.
This is the first I've heard of Innodb having massive performance issues.
Check out Karl Seguin's blog post.
Posted in mysql | No Comments »
Wednesday, May 30th, 2007
I didn't find any simple ways to determine how hard our mysql database was working, so I whipped this up. It uses a 10 second delay to figure out the queries per second average.
time=10
orig=`mysql -e "show status" | awk '{if ($1 == "Questions") print $2}'`
sleep $time
last=`mysql -e "show status" ...
Posted in mysql, tips | 1 Comment »
Thursday, May 17th, 2007
After banging my head against a wall for a while, I finally found this thread from June 2005 in the MySQL support forums regarding using variables in the LIMIT clause. They don't support it yet. There's no time table that indicates when it will be supported either. ...
Posted in mysql | 3 Comments »
Wednesday, May 2nd, 2007
Aggregates are awesome. But sometimes you want to do 2 counts in a query, and have one of them be more restrictive than the other. Lets say our database focuses on pictures, and rating them on a scale from 1-100. We want to know the average rating, ...
Posted in mysql | No Comments »