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Displaying posts with tag: sql (reset)
Why would anyone use a 32-bit OS in 2012?

I’ve been browsing some mailing lists and so on (it doesn’t matter which ones) and came across the Great 32-Bit Debate afresh. The debate always starts with someone saying “I need 32-bit support” or “this doesn’t work on 32-bit systems,” and someone else raising an objection to that, saying that nobody uses 32-bit systems anymore and anyone who does is doing something wrong.

Why would anyone use a 32-bit OS in the year 2012? I can think of a few very good reasons.

  1. The universe isn’t wholly x86_64 yet; there’s still ARM and other non-server systems.
  2. Developer laptops often run 32-bit operating systems, especially when Linux is the developer’s preference, because it works better with a lot of proprietary software such as Flash and audio drivers, and generally causes a lot less user headache. This is especially relevant because Ubuntu, Fedora, and other popular distributions are targeted towards …
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Designing a database interface for programmers

How do you connect to and converse with your database of choice (MySQL, in my case)? Chances are it’s largely formed by the programming language you choose. I’ve worked with a variety of programming languages. Anytime I begin learning a new one, I am reminded again that there’s more than one way to skin a cat.

Over the last few years, I’ve mostly programmed in Perl and shell. The shell interface to MySQL is simple: the mysql command-line tool. There is not much to think about. In Perl, however, the standard is to use DBI. I have grown accustomed to DBI over the years, but that doesn’t mean I like it. I think it’s one of the worst database APIs I’ve seen. The abstractions it uses (there are only two object abstractions: connections and “statement handles”) are awkward to the extreme.

It does get worse, though. PHP historically used libmysql’s C library for connecting to MySQL, and similarly used native …

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How to send input to many terminals

Do you ever find yourself wanting to open several terminal windows and send the same commands to all of them? I’ve had this need many times, and I’ve never found a completely satisfactory solution. I’ve also known a lot of people who’ve written various sets of scripts to help them accomplish such tasks.

In no particular order, here are a few ways I’ve done this in the past:

  1. Facebook’s pmysql client
  2. The dsh tool
  3. Several screen windows named remoteXXX, followed by a bash for-loop: while read cmd; do screen -X at remote# stuff "$cmd"; done
  4. Using many PuTTY windows and the puttycs tool
  5. Opening many tabs in KDE’s Kterm tool and selecting the options to send input to all tabs

Here …

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Implementing SQL with Unix utilities

As I’ve become a better shell programmer over the last year or two, I’ve been surprised to discover some tools I didn’t know about. It eventually dawned on me, as I did more and more brute-force processing of large datasets, as well as some of the more delicate things that went into Aspersa -> Percona Toolkit, that many tasks I used to do with SQL and spreadsheets can be accomplished easily with well-structured text files and Unix utilities. And they don’t require loading data into a database or spreadsheet (the latter of which almost always performs terribly).

To give an idea, here are some of the relational operations (in SQL speak) you can perform:

  1. SELECT col1, col2… can be implemented with several variants of Unix utilities: cut and awk are the two most obvious. I tend to use awk only when needed, or when it’s more convenient to combine …
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SHOW PROCESSLIST in MySQL 5.6

Mark Leith writes that it’s time to say goodbye to SHOW PROCESSLIST in MySQL 5.6, and use the Performance Schema replacement for it instead, because the older tools cause some blocking, and the Performance Schema replacement is completely non-blocking.

On the face of it that’s a good thing, but I wonder whether we’ll want to keep some blocking functionality around anyway. Inspecting systems that are doing concurrent work can be hard unless you can see a variety of views on them. One such is looking at the state of all the concurrent work at an instant in time. This is sometimes indispensable for troubleshooting: you will see causes and effects you’ll never see in counters and metrics, no matter how many you capture or how sophisticated the analysis.

I haven’t seen MySQL 5.6 in production usage …

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Percona Live CFP closing soon!

If you haven’t submitted your proposals for April’s Percona Live MySQL conference (the big annual one in Santa Clara California), now’s the time: the CFP closes in a couple of days!

Further Reading:

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Changes to InnoDB autoextend coming in MySQL 5.6

I was looking through James Day’s post on upcoming changes to MySQL configuration defaults in version 5.6, and one caught my eye in particular: innodb_autoextend_increment changes from 8 to 64MB, and now affects *.ibd files.

I don’t see any further documentation on this yet; I assume that’s in the works. I’m curious how this will actually behave. What will be the initial size of an empty InnoDB table using innodb_file_per_table? There might be some unintended consequences. Here’s a couple I can think of:

  1. Create a table and it’s 64MB from the start. This would cause some people to be unable to use InnoDB. In fact, as it currently stands, an empty table is 16kb, and I’ve heard some people say that’s a problem for them because they create many small tables and the 16kb …
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What’s the benefit of the cloud?

Given that most people don’t know what the cloud is, I guess we shouldn’t be surprised that most people can’t articulate the benefits of cloud computing clearly. I commonly hear “Scalability!” “Easy provisioning!” “Flexibility!” and so on. Of course, all of these are benefits you can get without the cloud. Theo says it pretty well, so I won’t belabor that point.

What do you think are the benefits of cloud computing?

In the end I can think of only one really unique benefit, and it’s indirect. It is this: the rise of cloud computing is creating a social phenomenon among engineers. The benefit isn’t the technology, or the economics, or any of that stuff. It’s the change …

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Adaptive fault detection in MySQL servers

I’ve just finished presenting my work on adaptive fault detection at Surge and Percona Live NYC. My slides are available on Slideshare, and embedded below.

Adaptive Fault Detection from xaprb

Further Reading:

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Binary log checksums in MySQL 5.6

MySQL 5.6 will have “checksums in the binary log,” which can be variously described, but one phrase I’ve heard a few times is, loosely, that it helps ensure replication integrity. This isn’t specific enough to make it clear what it does, and when I’ve talked about pt-table-checksum and its purpose (for example, on webinars), people often ask whether pt-table-checksum will be obsoleted by replication checksums in MySQL 5.6. The answer is no, they do completely different things. But it’s kind of confusing, a bit like semi-synchronous replication in that regard.

pt-table-checksum ensures that your replicas have the same logical dataset as their masters. They can drift for any number …

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