For some time, I’ve been digging through Memcached related articles and blog posts over the web in order to understand how people are actually using it. Most of the articles are kinda equivalent. But the use of version in the cache seems more standard and improve form of managing the cache. When, cache keys are managed using version numbers, one does not have to worry about cache conflict issues also that may occur in certain update transactions because Memcached use LRU (Least Recently Used) to remove old cache values.

Here are some links I have gone through:

• http://code.google.com/p/memcached/ (Main resource)
• http://www.linuxjournal.com/article/7451
• http://blog.leetsoft.com/2007/5/22/the-secret-to-memcached
• http://dev.mysql.com/doc/refman/5.1/en/ha-memcached-faq.html
• http://www.igvita.com/2008/04/22/mysql-conf-memcached-internals/
• http://highscalability.com/strategy-break-memcache-dog-pile
• http://abhinavsingh.com/blog/2009/01/memcached-and-n-things-you-can-do-with-it/

I learned something new today regarding MySQL.

The use of binary operator if used in a query or as collation type in DDL can make some significant difference in the results. Generally, when we create some table in MySQL, we don’t use binary collation. For example:

CREATE TABLE students (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(255) NOT NULL
)ENGINE=MYISAM CHARACTER SET utf8 COLLATE utf8_unicode_ci;

Now Lets insert some data

INSERT INTO stduents set name = 'Prajwal Tuladhar';
INSERT INTO stduents set name = 'PrAJwal TUladhar';

If a query is run in the above table:

mysql> SELECT *
    -> FROM students
    -> WHERE name = 'Prajwal Tuladhar';
+----+------------------+
| id | name             |
+----+------------------+
|  1 | Prajwal Tuladhar |
|  2 | PrAJwal TUladhar |
+----+------------------+
2 rows in set (0.00 sec)

So, if we want case sensitive results from a case insensitive table as above:

mysql> SELECT *
    -> FROM students
    -&gt; WHERE <strong>binary</strong> name = 'Prajwal Tuladhar';
+----+------------------+
| id | name             |
+----+------------------+
|  1 | Prajwal Tuladhar |
+----+------------------+
1 row in set (0.00 sec)

Or we can just changed the collation of the table as:

ALTER TABLE `students`  DEFAULT CHARACTER SET utf8 COLLATE utf8_bin

More information about binary operator here.