Arsenal SAM7R Instruction Manual

The SAM7R-61 is a high quality Bulgarian-made AK47 rifle chambered in 7.62x39mm. It features a milled receiver and a chrome lined hammer-forged barrel.

Arsenal SAM7R-61

• 14mm muzzle threads
• muzzle break
• cleaning rod
• bayonet lug
• black polymer furniture
• intermediate length buttstock
• scope rail
• one 10-round magazine
• sling
• oil bottle
• cleaning kit

The SAM7R also comes in a California compliant model (the SAM7R-61C) that has a non-detachable magazine (you need to use their provided tool to release the mag).

Arsenal SAM7R Instruction Manual

pg_sample: extract a sample dataset from a larger PostgreSQL database

pg_sample is a PostgreSQL utility for making smaller versions of large databases.

download pg_sample 0.01

When you have a relatively large database (tables with, say, millions or billions of rows), it can be difficult to generate smaller datasets to work with, especially if foreign keys are heavily used.

That's where this script comes in. It will create smaller instances of each table along with any additional rows needed to satisfy foreign key constraints (circular dependencies are supported).

The script's operation closely resembles that of pg_dump. For example, assuming we have a large database named largedb, a smaller version could be produced with:

  createdb smalldb
  pg_sample largedb | psql smalldb

The smalldb would then contain a subset of largedb's data.

Here are the command-line options (many of which mirror pg_dump):

    -a
    --data-only
        Output only the data, not the schema (data definitions).

    -E *encoding*
    --encoding=*encoding*
        Use the specified character set encoding. If not specified, uses the
        environment variable PGCLIENTENCODING, if defined; otherwise, uses
        the encoding of the database.

    -f *file*
    --file=*file*
        Send output to the specified file. If omitted, standard output is
        used.

    --force
        Drop the sample schema if it exists.

    --keep
        Don't delete the sample schema when the script finishes.

    --limit=*number*
        The maximum number of rows to initially copy from each table
        (defaults to 100). Note that sample tables may end up with
        significantly more rows in order to satisfy foreign key constraints.

    --random
        Randomize the rows initially selected from each table. May
        significantly increase the running time of the script.

    --schema=*name*
        The schema name to use for the sample database (defaults to
        _pg_sample).

    --trace
        Turn on Perl DBI tracing. See the DBI module documentation for
        details.

    --verbose
        Output status information to standard error.

    The following options control the database connection parameters.

    -h *host*
    --host=*host*
        The host name to connect to. Defaults to the PGHOST environment
        variable if not specified.

    -p *port*
    --port=*port*
        The database port to connect to. Defaults to the PGPORT environment
        variable, if set; otherwise, the default port is used.

    -U *username*
    --username=*username*
        User name to connect as.

    -W *password*
    -password=*password*
        Password to connect with.

See also: pg_sample Github source repository

ip2host 1.11 Release

A new release of ip2host is now available. It's a small maintenance release incorporating changes from the Debian package maintainer. The source repository has also been moved to Github.

http://github.com/mla/ip2host

DESCRIPTION

    Resolves IPs to hostnames in web server logs. This is a faster, drop-in
    replacement for the logresolve utility distributed with the Apache web
    server.

CHANGELOG

ip2host 1.11

  * Silence warnings thanks to Andrew McNaughton and Gunnar Wolf
    http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=563129

Installing Adobe AIR on 64-bit Ubuntu 9.10 Linux

Adobe AIR isn't currently available for 64-bit Linux, but they provide instructions on running the 32-bit version.

I've converted the Ubuntu instructions into this shell script:
http://sites.google.com/site/mlawire/installing-adobe-air-1-5-on-64-bit-ubuntu-linux/install-adobe-air-ubuntu-64bit.sh

From a terminal:

wget http://sites.google.com/site/mlawire/installing-adobe-air-1-5-on-64-bit-ubuntu-linux/install-adobe-air-ubuntu-64bit.sh
chmod a+rx install-adobe-air-ubuntu-64bit.sh
sudo ./install-adobe-air-ubuntu-64bit.sh

This worked for me on Ubuntu 9.10. Please let me know if you try it on other Ubuntu releases or otherwise have trouble with it.

Keywords: Installing Adobe AIR 64-bit Linux Ubuntu

Doxygen Example

Doxygen is a documentation system for use with many languages, including C++, C, Java, and Python.

First, install Doxygen. Using Ubuntu, I installed the package with:

$ apt-get install doxygen

Next. enter the source directory of a project you're working on and run:

$ doxygen -g

That will create a config file named Doxyfile in the current directory. You can customize it, but we'll accept the defaults for now.

Now begin writing your documentation. Here's an example of documenting a simple C++ program:

#include <iostream>

using namespace std;

/**
 * @brief Example class to demonstrate basic Doxygen usage
 * @author MLA
 *
 * This is a simple class to demonstrate how Doxygen is used.
 * It implements the Euclidean algorithm to compute the greatest
 * common divisor of two numbers.
 */

class Euclid {
  public:
    
    /**
     * Compute the greatest common divisor of two integers.
     *
     * @param a first integer
     * @param b second integer
     * @return greatest common divisor of a and b
     */
    static const int gcd(const int a, const int b) {
      if (0 == b) return a;
      return gcd(b, a % b);
    }
};

Finally, run doxygen, which will process the files and generate documentation in the html subdirectory:

$ doxygen

For more details, see the Doxygen homepage.

C++ Constant for PI

Where's the definition for pi? Doesn't C++ provide a constant? What about C?

The C++ standard doesn't provide a value for pi but it's simple to define yourself:

#include <iostream>
#include <cmath> // M_PI is not standard

using namespace std;

class MathConst {
  public:
    static const long double PI;
};

const long double MathConst::PI = acos((long double) -1);

int main() {
  cout.precision(100);
  cout << "PI ~ " << MathConst::PI << endl;
}

Output:

$ g++ MathConst.cpp -o pi
$ ./pi 
PI ~ 3.14159265358979323851280895940618620443274267017841339111328125

That is accurate to 18 decimal places.

Here's a definition in C:

#include <math.h>
#include <stdio.h>

double pi() {
  const double pi = acos((double) - 1);
  return pi;
}

int main() {
  printf("%.20f\n", pi());
  return 0;
}

Postgresql: Indexes on Foreign Keys

This query identifies foreign keys that are potentially missing indexes (Postgresql does not create indexes on foreign keys automatically).

/*
  Look for foreign key constraints that are missing indexes on the
  referencing table.

  Orders results by the size of the referencing table, largest first,
  on the assumption that, all else being equal, they are the most likely
  to benefit from the addition of indexes.

  This is only meant as a starting point, and isn't perfect.
  It's possible, for example, that it will report a missing index
  when in fact one is available. e.g., it won't realize that an index on
  (f1, f2) could be used with a fk on (f1). However, it will recognize
  that an index on (f1, f2) can be used with a fk on (f2, f1).

  Usage: psql -q dbname -f pg-find-missing-fk-indexes.sql
*/

CREATE FUNCTION pg_temp.sortarray(int2[]) returns int2[] as '
  SELECT ARRAY(
      SELECT $1[i]
        FROM generate_series(array_lower($1, 1), array_upper($1, 1)) i
    ORDER BY 1
  )
' language sql;

  SELECT conrelid::regclass
         ,conname
         ,reltuples::bigint
    FROM pg_constraint
         JOIN pg_class ON (conrelid = pg_class.oid)
   WHERE contype = 'f'
         AND NOT EXISTS (
           SELECT 1
             FROM pg_index
            WHERE indrelid = conrelid
                  AND pg_temp.sortarray(conkey) = pg_temp.sortarray(indkey)
         )
ORDER BY reltuples DESC
;