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Displaying posts with tag: server (reset)
ActiveMQ Tips: Flow Control and Stalled Producers Problem

It’s been a few months since we‘ve started actively using ActiveMQ queue server in our project. For some time we had pretty weird problems with it and even started thinking about switching to something else or even writing our own queue server which would comply with our requirements. The most annoying problem was the following: some time after activemq restart everything worked really well and then activemq started lagging, queue started growing and all producer processes were stalling on push() operations. We rewrote our producers from Ruby to JRuby, then to Java and still – after some time everything was in a bad shape until we restarted the queue server.

So, long story short, after a lots of docs and source code reading we’ve found really interesting thing. There is a “feature” added in the recent ActiveMQ release …

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XenServer 5 with OpenBSD

Here is my experience trying to run OpenBSD with XenServer 5 Enterprise.

  • XenServer console doesn’t function properly as it keeps overlaying text displayed previously or anything you have typed into the console. Makes it very difficult to read and see what you are doing. As well it appears numerpad with numlock on does not work either. The best work around is to SSH into OpenBSD.
  • Receiving the following error messages at boot up, “clock: unknown CMOS layout” and “rl0: watchdog timeout”. Yes the NIC is being detected as a Realteak 8139. If I check /var/run/dmesg.boot out of the two error messages I only see the “clock: unknown CMOS layout”. So I would assume the watchdog timeout message occurs after initial boot sequence.
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MySQL - Can You Concatenate Strings From a Column Into a Single Row?

How would one concatenate strings from a column (multiple rows) into a single row using MySQL? I see its possible with MS SQL Server 2005 and above. Any incite into how to achieve this in MySQL would be much appreciated.

MS SQL Server 2005 - Example

SELECT Web_Account_ID,
GroupNameConcat = REPLACE(
                Web_Account_Group_Name_ID AS [DATA()]
                tblWebAccountGroup WAG
                WAG.Web_Account_ID = WA.Web_Account_ID
        ORDER BY
            FOR XML PATH ('')
        ), ' ', ',')
FROM tblWebAccounts WA
ORDER BY Web_Account_ID

Query Results Example

Source: …

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MySQL virtual columns

Wouldn't it be cool to enhance MySQL creation table syntax to do this?

my_date DATE,
my_month VIRTUAL INT AS (DATE_FORMAT(d,'%Y%m'))

And later, when you insert '2008-08-23' in my_date, then automatically my_month will be set to 200808.
Yes, it would be cool, and it has been done. Andrey Zhakov, a so far unknown to me community contributor, has extended the server code to implement virtual columns (WL#411) and functional indexes (WL#1075)
Andrey has published …

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Best MySQL Server Under $10K?

I want to get opinions from outside of my daily circle of people on the best server hardware to use for MySQL. I remember from the conference somebody (Pipes?) mentioning a particular Dell server with multiple disk RAID10 that could supposedly be had for about $6k but I completely misplaced the model number (Frank, did you get my email?).

I know that a multi-disk RAID array with a bunch of fast disks (15k RPM?) is probably the most important method of improving performance, followed by the amount of RAM, so I'm trying to find the best combination/balance of the two. However, server prices on the Internet range so much that I don't even know where to begin to tell a good deal from a bad one. I don't think SSDs can play a role here, because we …

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Community Statistics for Netbeans Database Usage

"The database support in NetBeans allows users to connect to a database and view and modify the database structure and data. These graphs show which database servers users connect to most often."

Of particular note, besides the large usage of MySQL and Oracle, is the large usage of Java DB (Derby), and the significant PostgreSQL usage.

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