Thursday, November 12, 2009

Gearman for MySQL


Gearman for MySQL
If you haven't yet heard about Gearman, it's time to have a look at it. Its distributed client server architecture are a perfect match for today's cloud oriented applications.
When talking about Gearman, much stress is often given on its scalability features, such as map/reduce and distributed loads. But Gearman has also a distinctive advantage in the feature department, because of its design that I like to describe as cooperation of the fittest.
While a traditional application is written entirely in a given language, or it must find ways of integrating multiple languages parts, Gearman encourages easy cooperation between parts written in different languages, eliminating the need for library translation, and allowing the best implementation of a feature to be used by another part of the application.
Today, November 12, at 14:00 UTC, there will be a MySQL University presentation on Gearman for MySQL.
One of the components created by Gearman enthusiasts is a MySQL Gearman UDF. Using this extension, you can easily define functions in any language you are familiar with, and then call that function from MySQL. Some examples shown in the presentation include shell access, regular expressions enhancements, storing results incrementally in a file, using language-specific library extensions, and your imagination can do the rest.
Using this sample worker code, you can then call the UDF function from MySQL with something like thge following:

select gman_do('reverse','abcd') as test;
+------+
| test |
+------+
| dcba |
+------+

SELECT gman_do('shell',
concat(' ls -lh ',
(select variable_value from information_schema.global_variables
where variable_name = "datadir" )))\G

total 40976
-rw-rw---- 1 gmax staff 5.0M Nov 11 13:34 ib_logfile0
-rw-rw---- 1 gmax staff 5.0M Nov 11 13:34 ib_logfile1
-rw-rw---- 1 gmax staff 10M Nov 11 13:34 ibdata1
-rw-rw---- 1 gmax staff 1.2K Nov 11 13:34 msandbox.err
drwx------ 2 gmax staff 2.4K Nov 11 13:34 mysql
-rw-rw---- 1 gmax staff 6B Nov 11 13:34 mysql_sandbox5140.pid
drwx------ 2 gmax staff 68B Nov 11 13:34 test


select gman_do('eval','2 * 3') ;
+-------------------------+
| gman_do('eval','2 * 3') |
+-------------------------+
| 6 |
+-------------------------+


select gman_do('eval',
concat('$_="',host,'";tr/a-z/b-za/; $_'))
as test from mysql.user;
+-------------+
| test |
+-------------+
| % |
| mpdbmiptu |
+-------------+

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