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Displaying posts with tag: code (reset)
Using Jenkins to parse sphinx warnings

At Percona, we’re now using sphinx for our documentation. We’re also using Jenkins for our  continuous integration. We have compiler warnings from GCC being parsed by Jenkins using the built in filters, but there isn’t one for the sphinx warnings.

Luckily, in the configuration page for Jenkins, the Warnings plugin allows you to specify your own filters. I’ve added the following filter to process warnings from sphinx:

For those who want to copy and paste: …

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MySQL HA Agent Mini HowTo

Why This Post
While testing Yoshinori Matsunobo's MHA agent I found that although the wiki has a very complete documentation, it was missing a some details. This article intends to close that gap and bring up some issues to keep in mind when you do your own installation. At the end of the article I added a Conclusions section, if you're not interested in the implementation details, but to read my take on the project, feel free to jump straight to the end from here.

My Test Case
Most of our production environments can be simplified to match the MHA's agent most simple use case: 1 master w/ 2 or more slaves and at least one more slave in an additional tier:

Master A --> …
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automysqlbackup 2.5.5

I spent my day doing updates to the automysqlbackup script.  Here is some of what I’ve added over the last year.

The bug number fixes are from SourceForge.

# 2.5.5 MTG – (2011-07-21)
#    – Bug – Typo Ureadable Unreadable config file line 424 – ID: 3316825
#    – Bug – Change “#!/bin/bash” to “#!/usr/bin/env bash” – ID: 3292873
#    – Bug – problem with excludes – ID: 3169562
#    – Bug – Total disk space on symbolic links – ID: 3064547
#    – Added DEBUG option to only print the commands that will be executed.
#    – Bug – WHICH command didn’t work if there …

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Timing queries in the 21st century (with LD_PRELOAD and sed)

So… Baron blogged about wanting higher precision timers from the mysql binary and that running sed on the binary wasn’t cutting it. However… I am not one to give up that easily!

This is what LD_PRELOAD was made for! Evil nasty hacks to make your life easier!

By looking at the source code, I can easily work out how this works… I just have to override two calls! They being sysconf() (we fake how many ticks per second there are) and times() (let’s return a much higher precision number).

Combined with the sed hack on the binary to change the sprintf call to print out the higher precision number, we have:

mysql> select count(*) from t1;
| count(*) |
|   710720 |
1 row in set (1.080110 sec)

Get it from my junkcode: …

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No implicit commit (on the road to transactional DDL)

A long time ago, in a time that can only serve to make some feel old and others older, MySQL didn’t support transactions. Each statement was executed as it went, there was no ROLLBACK (or COMMIT or crash recovery etc). Then there were transactions. Other RDBMSs implement auto_commit functionality, but for MySQL users, we think of it as the magic compatibility mode that (mostly) makes applications written for MyISAM magically work on InnoDB (okay, and making “you should use transactions” a really easy consulting gig :)

I’m currently working on finishing up a patch that removes the implicit COMMIT from DDL operations in Drizzle. Instead, you get an error message saying that Transactional DDL is not currently supported. I see a future where we have one of two situations (possibly depending on the storage engine): support DDL within normal transactions, DDL only transactions (cannot mix …

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Is your Storage Engine buggy or the database server?

If your storage engine returns an error from rnd_init (or doStartTableScan as it’s named in Drizzle) and does not save this error and return it in any subsequent calls to rnd_next, your engine is buggy. Namely it is buggy in that a) an error may not be reported back to the user and b) everything may explode horribly when rnd_next is called after rnd_init returned an error.

Unless it is running on MariaDB 5.2 or (soon, when the patch hits the tree) Drizzle.

Monty (Widenius, not Taylor) wrote a patch for MariaDB based on my bug …

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HandlerSocket plugin – NoSQL/SQL interactions

HandlerSocket is cool. But, it turns out there are a few issues.

Justin Swanhart points out HandlerSocket currently lacks atomic operations . Since HandlerSocket uses different connections for reading and writing, you can’t increment/decrement a value without creating a race condition.

Still, the idea of skipping SQL interpretation and just reading the data you know you want is a great one.  Writing data might even be better. But being able to use both SQL and NoSQL could be really wonderful.  What if we could use complex queries to update complex tables and pluck values out as needed.  For example, queries to analyze current weather conditions and produce forecasts that we could then retrieve via a location key? What about updating current condition data …

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Using HandlerSocket Plugin for MySQL with PHP

This document was updated and tested for CentOS 6.0

In my last two posts I installed the HandlerSocket plugin into MariaDB and showed how to use it with Perl.  That’s good, but if you are thinking of using HandlerSocket  I’m guessing you have a very high traffic website and it’s written in PHP.  In this post I’m going to connect HandlerSocket with PHP.  In the next post I’ll discuss using HandlerSocket on a production system.

There are a couple of HandlerSocket php modules projects.  I tried each of them and I found PHP-HandlerSocket was the best.  Both of them are still rough and neither of them have documentation beyond their source code.  Maybe this will move things forward.

Here are the applications you need to have installed that where not installed in my last two posts.  Run this to …

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MySQL 5.5 is GA and 5.5.8 missing from launchpad…

While it’s great that MySQL 5.5 is GA with the 5.5.8 release (you can download it here), I’m rather disappointed that the bzr repositories on launchpad aren’t being kept up to date. At time of writing, it looked like this:

Yep – nothing for five weeks in the 5.5 repo – nothing since the 5.5.7 release :(

There hasn’t been zero changes either – the changelog has a decent number of fixes.

Innobase 1.1.3 in Drizzle

In case you haven’t heard yet, I’ve merged in the latest InnoDB from MySQL 5.5.7 into Drizzle. The innobase plugin is now based on InnoDB 1.1.3.

This gets a lot of bug fixes and improvements from 1.1.2 (and on 1.1.1). Enjoy!

Showing entries 61 to 70 of 191
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