my ( $self, $table ) = @_;

  $self->{targetdb}{tables}{$table}{its_a_big_un} = 1;

  my $self = shift;

  for my $tablename ( keys %{$self->{targetdb}{tables}} ) {
    my $sourcetable;

    if( exists $self->{targetdb}{tables}{$tablename}{transfer} ) {
      next;
    }

    if( exists $self->{targetdb}{tables}{$tablename}{link} ) {
      $sourcetable = $self->{targetdb}{tables}{$tablename}{link};
      if( $sourcetable eq "" ) {
	# skip this table
	next;
      }
    } else {
      # find the sourcetable
      if( exists $self->{targetdb}{tables}{$tablename}{select} ) {

	# custom select, no check
	next;
      } elsif( ! exists $self->{sourcedb}{tables}{$tablename} ) {

	die "Couldnt find source for $tablename. Enter empty sourcetable.";

      } else {
	$sourcetable = $tablename;
      }
    }

    my @newcols = @{$self->{targetdb}{tables}{$tablename}{columns}};
    my @oldcols = @{$self->{sourcedb}{tables}{$sourcetable}{columns}};
    
    my %rename;

    if( exists $self->{targetdb}{tables}{$tablename}{columnrename} ) {
      %rename = %{$self->{targetdb}{tables}{$tablename}{columnrename}};
    } else {
      %rename = ();
    }

    # find all source columns and build select statement 

    for my $colname ( @newcols ) {
      my $selname;
      
      if( exists $rename{$colname} ) {
	$selname = $rename{$colname};
	if( $selname eq "" ) {
	  $selname = "NULL";
	}
      } else {
	my $colExists = 0;
	for my $oldcol ( @oldcols ) {
	  if(  $oldcol eq $colname ) {
	    $selname = $colname;
	    $colExists = 1;
	    last;
	  }
	}
	if( ! $colExists ) {
	  die "Couldnt fill $tablename.$colname\n";
	}
      }
    }
  }

  my $self = shift;
  for my $tablename ( keys %{$self->{targetdb}{tables}} ) {
    $self->target_dbh()->do( "delete from $tablename" );
  }

  my $self = shift;

  $self->source_dbh()->disconnect();
  $self->target_dbh()->disconnect();

  my ( $self, $newtable, $oldcol, $newcol ) = @_;
  $self->{targetdb}{tables}{$newtable}{columnrename}{$newcol} = $oldcol;

  my ( $self, $newtable,  $newcol ) = @_;
  $self->{targetdb}{tables}{$newtable}{columnrename}{$newcol} = "";

  my ( $self, $newtable, $select ) = @_;
  $self->{targetdb}{tables}{$newtable}{select} = $select;

  my $self = shift;
  my @ordered_table_list= @_;
  $self->{targetdb}{dofirst} =\@ ordered_table_list;
}

1;

  my ( $class, @args ) = @_;
  
  my $self = {};
  bless $self, $class;

  $self->source_dbh( $args[0] );
  $self->target_dbh( $args[1] );

  $self->read_dbs();

  return $self;

  my $self = shift;

  my $dbh;

  for my $db_name ('targetdb', 'sourcedb' ) {
    if( $db_name eq 'targetdb' ) {
      $dbh = $self->target_dbh();
    } else {
      $dbh = $self->source_dbh();
    }

    my $sth = $dbh->prepare( "show tables" );
    $sth->execute();

    while( my $arref = $sth->fetchrow_arrayref() ) {
      $self->{$db_name}{tables}{$arref->[0]} = {};
    }

    my @tables = keys %{$self->{$db_name}{tables}};
    for my $table ( @tables ) {
      $sth = $dbh->prepare( "show columns from $table" );
      $sth->execute();
      while( my $arref = $sth->fetchrow_arrayref () ) {
	push( @{$self->{$db_name}{tables}{$table}{columns}}, $arref->[0] );
      }
    }
  }

  my ( $self, $newtable, $row_modifier ) = @_;
  $self->{targetdb}{tables}{$newtable}{row_modify} = $row_modifier;

  my ( $self, $arg ) = @_;
  
  ( defined $arg ) &&
    ( $self->{'source_dbh'} = $arg );

  return $self->{'source_dbh'};

  my ( $self, $sourcetable, $targettable, $tmpfile ) = @_;
  
  my $sourcedb = $self->source_dbh();
  my $targetdb = $self->target_dbh();

  # look for custom select
  my $select = "";
  if( exists $self->{targetdb}{tables}{$targettable}{select} ) {
    $select = $self->{targetdb}{tables}{$targettable}{select};
  } else {
    # check if all columns have matching names
    my @newcols = @{$self->{targetdb}{tables}{$targettable}{columns}};
    my @oldcols = @{$self->{sourcedb}{tables}{$sourcetable}{columns}};
    
    my %rename;

    if( exists $self->{targetdb}{tables}{$targettable}{columnrename} ) {
      %rename = %{$self->{targetdb}{tables}{$targettable}{columnrename}};
    } else {
      %rename = ();
    }

    # find all source columns and build select statement 

    for my $colname ( @newcols ) {
      my $selname;

      if( exists $rename{$colname} ) {
	$selname = $rename{$colname};
	if( $selname eq "" ) {
	  $selname = "NULL";
	}
      } else {
	my $colExists = 0;
	for my $oldcol ( @oldcols ) {
	  if(  $oldcol eq $colname ) {
	    $selname = $colname;
	    $colExists = 1;
	    last;
	  }
	}
	if( ! $colExists ) {
	  die "Couldnt fill $targettable.$colname\n";
	}
      }

      $select .= " $selname,";
    }
    chop( $select );
    $select = "SELECT $select from $sourcetable";
  }    
		   
  # MySQL specific ...
  # DBD doesn't use cursors; loads whole table during execute()
  # problem for large tables - "mysql_use_result" gets around this
  my $sth;
  if (defined $self->{targetdb}{tables}{$targettable}{its_a_big_un}) {
    $sth = $self->source_dbh()->prepare( $select , { mysql_use_result => 1 } );
  }
  else {
    $sth = $self->source_dbh()->prepare( $select );
  }
  $sth->execute();
  
  my $row;
  if( exists $self->{targetdb}{tables}{$targettable}{row_modify} ) {
    my $rowmod = $self->{targetdb}{tables}{$targettable}{row_modify};

    while( my $arref = $sth->fetchrow_arrayref() ) {

      $row = &{$rowmod}($arref);

      print $tmpfile ( join( "\t",@{$row} ),"\n" );
    }
  } else {
    while( my $arref = $sth->fetchrow_arrayref() ) {
      $row = join( "\t", @$arref );
      print $tmpfile "$row\n";
    }
  }

  my ( $self, $oldtable, $newtable ) = @_;
  $self->{targetdb}{tables}{$newtable}{link} = $oldtable;

  my ( $self, $newtable ) = @_;
  $self->{targetdb}{tables}{$newtable}{link} = "";

  my ( $self, $arg ) = @_;
  
  ( defined $arg ) &&
    ( $self->{'target_dbh'} = $arg );

  return $self->{'target_dbh'};

  my ( $self, $arg ) = @_;
  
  ( defined $arg ) &&
    ( $self->{'tmp_dir'} = $arg );

  return $self->{'tmp_dir'};

  my $self = shift;
  
  local *FH;
  my $tmpdir;

  if( ! defined $self->tmp_dir() ) {
    $self->close_dbh();
    die( "No tmp_dir specified" );
  } else {
    $tmpdir = $self->tmp_dir();
  }

  # first we should check if all standard trnasfers can go
  # otherwise testing this is a pain
  $self->check_possible_transfer();
  my @ordered_tables = $self->{targetdb}{dofirst};
  my %all_tables = %{$self->{targetdb}{tables}};
  for my $tablename ( @ordered_tables ) {
    delete $all_tables{$tablename};
  }
  for my $tablename ( keys %all_tables ) {
    push( @ordered_tables, $tablename );
  }

  for my $tablename ( @ordered_tables ) {
    my $skip = 0;
    print STDERR "Transfer $tablename ";

    open( FH, ">$tmpdir/$tablename.txt" ) or die "cant open dumpfile";
    
    if( exists $self->{targetdb}{tables}{$tablename}{transfer} ) {
      my $transfunc = $self->{targetdb}{tables}{$tablename}{transfer};
      &$transfunc( $self->source_dbh(), $self->target_dbh(), $tablename,\* FH );
    } else {
      my $sourcetable;
      if( exists $self->{targetdb}{tables}{$tablename}{link} ) {
	$sourcetable = $self->{targetdb}{tables}{$tablename}{link};
	if( $sourcetable eq "" ) {
	  # skip this table
	  $skip = 1;
	}
      } else {
	# find the sourcetable
	if( exists $self->{targetdb}{tables}{$tablename}{select} ) {

	  # if we have custom select, sourcetable doesnt make sense
	  $sourcetable = undef;

	} elsif( ! exists $self->{sourcedb}{tables}{$tablename} ) {

	  die "Couldnt find source for $tablename. Enter empty sourcetable.";

	} else {
	  $sourcetable = $tablename;
	}
      }
      if( ! $skip ) {
	$self->standard_table_transfer( $sourcetable, $tablename,\* FH );
      }
    }

    close FH;

    if( ! $skip ) {
      $self->target_dbh->do( "load data infile '$tmpdir/$tablename.txt' into table $tablename" );
    }

    # upload ?
    unlink "$tmpdir/$tablename.txt";
    print STDERR " finished\n";
  }

  # close databases
  
}


# this function checks if a standard transfer is possible.
# custom selects and custom transfer functions are not checked
# it will only return if it can do the transfer otherwise die