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10 Newer Entries Showing entries 61 to 70 of 82 10 Older Entries

Displaying posts with tag: configuration (reset)

More on variables ambiguities
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Continuing Variables ambiguities in names and values, there are two more issues I wish to present.

First, I’ve shown that variable values may be ambiguous. Thus, 1 and ON are interchangeable. But also 1 and YES.

The important thing to note is that it’s not always like that. You can’t just swap 1 for ON or YES as you will: it depends on the variable. Thus, a specific variable (e.g. query_cache_type) …

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Variables ambiguities in names and values
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Writing up some scripts, I see more and more ambiguities with regard to global variables.

For one thing, the names ambiguity between the hyphen (’-') and the underscore (’_'). So wait_timeout and wait-timeout are the same variable.

But just check out the many levels of inconsistency:

  • Command line arguments (e.g. run mysqld with option variables) use the hyphen convention
  • mysql –verbose –help shows the hyphen convention
  • SHOW GLOBAL VARIABLES uses the underscore convention
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What Exactly is Swappiness?
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This is an issue that keeps rearing its ugly head over and over again, and since it greatly affects performance, it is most important that DBAs of any DMBS running on Linux come to grips with it. So I decided to do some research and try different settings on my notebook. Here are my findings.

What can you find on the web?

A Wikipedia search for the word swappiness will come up empty (any volunteers out there want to write an article?). A Google search will show some pretty old material—the best article I found is from 2004: Linux: Tuning Swappiness. This article includes a …

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Lost and Found ?
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Sometimes you just have to laugh at the crazy things that can kill a good evening. I had this brilliant idea to change our replication setup on one of our Master-Master replication server setups this week. I got sick of having to restart MySQL every time we wanted to add a new database and have it included in the list of replicated databases - we were using replicate-do-db in our configs.So it

Linux and open source no puff in the clouds
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UPDATED - I had to update this post after a conversation with RightScale founder and CTO Thorsten von Eicken and for Sun’s Open Cloud announcement, which are both now included below.

There has been some substantial technology and news regarding open source software in cloud computing lately. More proof that open source is reaching into nearly all aspects of enterprise and broader IT, and also reinforcement of the idea that open source software will continue to have a pervasive and disruptive impact on the way organizations of all shapes and sizes do their computing and deal with their data.

First up is RightScale, which as detailed by 451 colleague …

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MySQL User Group Meetings in Israel
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This is a short note that the MySQL User Group Meetings in Israel are established (well, re-established after a very long period).

Thanks to Eddy Resnick from Sun Microsystems Israel who has set up the meetings. So far, we’ve had 2 successful meetings, and we intend to have more! First one was in Sun’s offices in Herzlia; second one, held last week, was at Interbit (a MySQL training center) in Ramat Gan. We hope to hold these meetings on a monthly basis, and the next ones are expected to be held at Interbit.

A new (blessed) law in Israel forbids us from sending invitations for these …

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Concluded my first MySQL University Session about MySQL backups using file system snapshots - some questions remained unanswered...
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Today I gave my first MySQL University session as a speaker, talking about Backing up MySQL using file system snapshots. The talk went quite well (at least that was my impression) and we had ~10 people attending. The slides (PDF) and a recording of the session are …

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Manually installing multiple MySQL instances on Linux: HOWTO
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Installing a single MySQL instance on a linux machine is a very simple operation. It may be as simple as:

apt-get install mysql-server

But you cannot use this method to install another MySQL instance. Moreover, if you try to manually install another instance, you may find that some collisions occur.

For example, when trying to install two 5.0 servers, apt-get or yum will just tell me “package is already installed”.

When trying to install a new 5.1 server along with 5.0, an implicit upgrade is performed.

But even if we try forcing the installation, there are collisions:

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cmon 0.13 released
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The main fixes in cmon 0.13 are:

  • filtering of clusterlog
  • better graphs interface with filtering
  • fixed bug in load average graphs. Now the loadavg graphs works
  • added replication role, socket when adding a mysql server to be monitored from the web interface.
  • corrected bug with how often mysql_variables are collected
  • fixed problems with graphs
  • added images directory
  • revamped graphs - now producing files in images directory,
  • ajax support for Storage graphs

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MySQL security: data integrity issues
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MySQL’s security model is not as elaborate as other popular databases. It’s missing quite a lot.

I wish to point out what I think are some very disturbing security holes, which may affect the database integrity.

This post is not about Roles, Kerberos, IPs and such. It’s about simple MySQL features, which allow common, unprivileged users, to break data integrity by using unprotected session variables.

I will consider three such issues.

We will assume a database with two tables, and two users.

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10 Newer Entries Showing entries 61 to 70 of 82 10 Older Entries

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