1
 ?    is list:

    [ [node1], 'key1a', 'key2a' ]
    [ [node2], 'key1a', 'key2b' ]
    [ [node3], 'key1b', 'key2a', 'key3a' ]

The nodes are ordered by key, depth-first.

The $node argument can be used to focus on a sub-tree.
If not specified it defaults to $dbh->{Profile}{Data}.

The $path argument can be used to specify a list of path elements that will be
added to each element of the returned list. If not specified it defaults to a a
ref to an empty array.

=head2 as_text

  @txt = $dbh->{Profile}->as_text();
  $txt = $dbh->{Profile}->as_text({
      node      => undef,
      path      => [],
      separator => " > ",
      format    => '%1$s: %11$fs / %10$d = %2$fs avg (first %12$fs, min %13$fs, max %14$fs)'."\n";
      sortsub   => sub { ... },
  );

Returns the collected data ($dbh->{Profile}{Data}) reformatted into a list of formatted strings.
In scalar context the list is returned as a single concatenated string.

A hashref can be used to pass in arguments, the default values are shown in the example above.

The C<node> and <path> arguments are passed to as_node_path_list().

The C<separator> argument is used to join the elements of the path for each leaf node.

The C<sortsub> argument is used to pass in a ref to a sub that will order the list.
The subroutine will be passed a reference to the array returned by
as_node_path_list() and should sort the contents of the array in place.
The return value from the sub is ignored. For example, to sort the nodes by the
second level key you could use:

  sortsub => sub { my $ary=shift; @$ary = sort { $a->[2] cmp $b->[2] } @$ary }

The C<format> argument is a C<sprintf> format string that specifies the format
to use for each leaf node.  It uses the explicit format parameter index
mechanism to specify which of the arguments should appear where in the string.
The arguments to sprintf are:

     1:  path to node, joined with the separator
     2:  average duration (total duration/count)
         (3 thru 9 are currently unused)
    10:  count
    11:  total duration
    12:  first duration
    13:  smallest duration
    14:  largest duration
    15:  time of first call
    16:  time of first call

=head1 CUSTOM DATA MANIPULATION

Recall that C<< $h->{Profile}->{Data} >> is a reference to the collected data.
Either to a 'leaf' array (when the Path is empty, i.e., DBI_PROFILE env var is 1),
or a reference to hash containing values that are either further hash
references or leaf array references.

Sometimes it's useful to be able to summarise some or all of the collected data.
The dbi_profile_merge_nodes() function can be used to merge leaf node values.

=head2 dbi_profile_merge_nodes

  use DBI qw(dbi_profile_merge_nodes);

  $time_in_dbi = dbi_profile_merge_nodes(my $totals=[], @$leaves);

Merges profile data node. Given a reference to a destination array, and zero or
more references to profile data, merges the profile data into the destination array.
For example:

  $time_in_dbi = dbi_profile_merge_nodes(
      my $totals=[],
      [ 10, 0.51, 0.11, 0.01, 0.22, 1023110000, 1023110010 ],
      [ 15, 0.42, 0.12, 0.02, 0.23, 1023110005, 1023110009 ],
  );        

$totals will then contain

  [ 25, 0.93, 0.11, 0.01, 0.23, 1023110000, 1023110010 ]

and $time_in_dbi will be 0.93;

The second argument need not be just leaf nodes. If given a reference to a hash
then the hash is recursively searched for for leaf nodes and all those found
are merged.

For example, to get the time spent 'inside' the DBI during an http request,
your logging code run at the end of the request (i.e. mod_perl LogHandler)
could use:

  my $time_in_dbi = 0;
  if (my $Profile = $dbh->{Profile}) { # if DBI profiling is enabled
      $time_in_dbi = dbi_profile_merge_nodes(my $total=[], $Profile->{Data});
      $Profile->{Data} = {}; # reset the profile data
  }

If profiling has been enabled then $time_in_dbi will hold the time spent inside
the DBI for that handle (and any other handles that share the same profile data)
since the last request.

Prior to DBI 1.56 the dbi_profile_merge_nodes() function was cal