4J

Here's an interesting product called "d3o" that provide amazing impact protection.

Some movies:

First, the official d3o movie:



And here's a Discovery channel clip:



Can't wait to play with it myself :-)

Found this video on the SEACOM site. Interesting background.

Ah... This is how ADSL should be :-)

Trailer



And here is a look at two other short clips:

"Alive in Joburg" on which District 9 was based:



And"Tetra Vaal":

Building on the script of yesterday, I have created a subroutine that will create a table if it doesn't exist. It also uses a DB connect retry for up to an hour in cases where the DB is not available.

The input arg's of the sub:

1. The table name
2. The table create definition

Here is the script:

sub CheckTables {

       my( $tblname, $tbldef ) = @_;

       # Connect to DB
       my $cont     = 0;
       my $tries    = 0;
       my $dbh1;
       while( not $cont ) {

               $tries++;
               eval {
                      
                       $dbh1 = DBI->connect( "dbi:mysql:database=$dbdb;host=$dbhost;port=$dbport", "$dbuser", "$dbpass" );

               };

               if( $@ ) {
      
                       sleep( 1 );
                      
               } else {
      
                       $cont++;

               }

               if( $tries > 3600 ) {
      
                       # We have been trying for an hour - give up
                       print "CheckTables_GIVE_UP\t1\n";
                       exit;
                              
               }

       }

       my $sql         = "show tables like '$tblname'";
       my $sth         = $dbh1->prepare( $sql );
       my $exists      = 0;
       if( $sth->execute() ) {
                      
               while( my $t = $sth->fetchrow_array() ) {
              
                       if( $t =~ /^$tblname$/ ) { $exists = 1; }

               }              
                      
       }

       # If table didn't exist, create it
       if( not $exists ) {
      
               # Attempt to create table
               $dbh1->do( $tbldef );

               # Check again
               $sth    = $dbh1->prepare( $sql );
               if( $sth->execute() ) {
                      
                       while( my $t = $sth->fetchrow_array() ) {
              
                               if( $t =~ /^$tblname$/ ) { $exists = 1; }

                       }              
                      
               }

       }

       $dbh1->disconnect;

       return $exists;

}

While working on Hadoop, I found that connecting to a DB to get or insert data presented a problem as you often need more connections then what's available. My solution right now is to "wait" for a connection to become available - without using any fancy queuing mechanisms:

# Connect to DB
my $cont   = 0;
my $tries  = 0;
my $dbh1;
while( not $cont ) {

       $tries++;
       eval {
                      
               $dbh1 = DBI->connect( "dbi:mysql:database=$dbdb;host=$dbhost;port=$dbport", "$dbuser", "$dbpass" );

       };

       if( $@ ) { sleep( 1 ); } else { $cont++; }

       if( $tries > 3600 ) {
      
               # We have been trying for an hour - give up
               print "GIVE_UP\t1\n";
               exit;
                      
       }

}

And that's it. When the while loop finally exists, you have a DB handle to use. In the above example we retry for more then an hour - which should be sufficient for most scenarios.

Hope some one else find it useful as well.

Labels: database, hadoop, mysql, perl