Identifying The Hottest Tables (Informix)

Yesterday I posted about how to identify the hottest table in a PostgreSQL database. Pretty much the same functionality is available for administrators of Informix databases as well; this kind of information is found in the sysmaster database which is the database engine's own database.

Identifying The Hottest Tables (PostgreSQL)

In recent versions of PostgreSQL there is a magical view called pg_stat_user_tables which provides per table information on usage; there is one row per table and eight counters per row.

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Querying Connectivity

You're application almost always needs to know if there is a working network connection. This is typically handled by placing the connection attempt in a try...catch block. That works, but can be slow, and it means the UI can't really adapt to the level of current connectivity. A much better solution is to query the NetworkManager [used by every mainstream distribution] via the System D-Bus for the current connectivity.

Converting M4B's to MP3

I ended up with some M4B audio files; these are "MPEG v4 system, iTunes AAC-LC" files. In order to reliably manage these files along with every other audio file [all of which are MP3] the simplest solution is just to convert them to MP3. In order to accomplish that I dumped them back out to WAV using mplayer and re-encoded them to MP3 using lame.

Where and what is /var/run/named?

    # service named start
    Starting name server BIND checkproc: Can not stat /var/run/named/named.pid: Too many levels of symbolic links
    - Warning: /var/run/named/named.pid exists! start_daemon: Can not stat /var/run/named/named.pid: Too many levels of symbolic links                                                          done

Changing Your FreeNode Password

There is no shortage of documentation for common IRC operations like registering your nick and managing channels. But I had quite the time figuring out the syntax for changing my password; turns out it's obvious:

    /ns set password new_password

There is no password confirmation - so make sure you type it correctly.

On a related note, for anyone new to IRC, it is possible to bind multiple nicks to your FreeNode account. Just switch to the nick you want to bind and then issue the "group" command.

Compression & Decompress Of A Stream

So far in Python I had not found a good method / module for performing compression and decompression of data as streams; most tools required files to be compressed which has some obvious limitations. But then I saw a mention of pyLZMA roll by. It supports compression and decompression of streams using the Lempel–Ziv–Markov chain algorithm.

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Printing Via LPR

If you have a Python app, or almost any kind of app, the accepted manner for printing is to use some kind of subprocess to invoke some command-line utility to submit the print job. Of course this requires that the underlying subsystems are aware of printers [and thus run a printer subsystem]. It also assumes the name of the command-line utility, the permissions are adequate to execute it, and all manner of other things. To put it simply: this is terrible! Why does my web server, workflow server, etc... need to run a print service?

SQLAlchemy & Upcoming Birthdays

OpenGroupware Coils uses SQLAlchemy as it's ORM. One of the desired features was a Logic command that efficiently returns contacts with upcoming birthdays. In raw SQL this query would be very simple to write - but how to do it in SQLAlchemy? The answer: sql.expression.extract which will create an expression column equivalent to EXTRACT. With EXTRACT it is possible to compare to the year-of-day represented by a date. The Python code looks like:

XSLT Transform to TXT, with LXML

Maybe this should be obvious, but it wasn't to me. I've got an XML document and an XSLT stylesheet. But that stylesheet just produces text, not XML; it is essentially a template for an e-mail. So I was extending OIE's transformAction for performing XSLT transforms that produce other than XML... but the documentation is a bit thin and every example is XML results. The trick is pretty simple, just

unicode(result)

and make sure [of course] that you have

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