Month: August 2011

MySQL Global status difference using single query

MySQL

Have just read MySQL Global status difference using MySQL procedures / functions, by Andres Karlsson. Have commented, but realized I did not provide with a direct answer. In the comment, I suggested checking out a solution based on views, found in common_schema. But the solution in common_schema is split into two views, due to the fact views cannot handle derived tables subqueries.

Well, here’s a single query to do that: it checks GLOBAL_STATUS twice, 10 seconds apart in the following sample. It uses SLEEP() to actually wait between the two reads. Yes, you can do that with a query.

The following query shows all GLOBAL_STATUS values that have changed during the sample period.

[UPDATE] query updated to work with MySQL 5.6 optimizer Continue reading ยป “MySQL Global status difference using single query”

Finding CURRENT_USER for any user

MySQL

A MySQL account is a user/host combination. A MySQL connection is done by a user connecting from some host.

However, the user/host from which the connection is made are not the same as the user/host as specified in the account. For example, the account may be created thus:

CREATE USER 'temp'@'10.0.0.%' IDENTIFIED BY '123456';

The host as specified in the above account is a wildcard host. A connection by the ‘temp’ user from ‘10.0.0.3’ can map into that account. It thus happens that the connected user is ‘temp’@’10.0.0.3’, yet the assigned account is ‘temp’@’10.0.0.%’.

MySQL provides with the USER() and CURRENT_USER() which map to the connected user and the assigned account, respectively, and which lets the current session identify the relation between the two. Read more on this on the MySQL docs.

The problem

And the trouble is: MySQL only provides this functionality for the current session. Surprisingly, given a user/host combination, I cannot get MySQL to tell me which account matches those details.

The inconsistency

And I care because there is an inconsistency. Namely, when I do SHOW PROCESSLIST MySQL tells me the user & host from which the connection is made. It does not tell me the account for which the process is assigned. Continue reading ยป “Finding CURRENT_USER for any user”

Speaking at “August Penguin 2011”

MySQL

I will be speaking at August Penguin 2011 (ืื•ื’ื•ืกื˜ ืคื™ื ื’ื•ื•ื™ืŸ), on August 12th in Ramat-Gan, Israel.

August Penguin is the annual meeting of Hamakor society: an Israeli society for Free Software and Open-Source Code (read more here).

I’ll be holding a non-technical talk about MySQL, titled “MySQL and the Open Source Sphere”. In this talk I will be presenting my impressions of the nature of open source development of MySQL and surroundings: the core server, the various forks, patches, 3rd party tools, companies involved, etc. So this is a general “get to know who’s who & what’s what in the MySQL world”.

This is a 30 minutes talk. I will surely not cover every open source development in this field, so my apologies in advance to those I leave out. The truth is, there’s so much going on lately I can hardly keep up with reading the announcements. Truly, this is a wonderful time for open source development with MySQL.

Talk will be held in Hebrew.

See you there!