On Jun 23, 2007, at 11:52 AM, Matt S Trout wrote:
On Fri, Jun 22, 2007 at 03:28:20PM -0400, Christopher Heschong wrote:
So I have this search:
my $addr = 16843009;
$rs->search( {
address => { '<=', $addr },
$addr => \'<= (address - 1 + (2 << 31 - bits))'
});
(Essentially, this finds the parent networks of an IP address
whose int
val is $addr (aka 1.1.1.1))
And I want to turn it into a join (so I can prefetch it), but I'm
running
into problems. I've tried something like this:
__PACKAGE__->belongs_to( parent => 'MyApp::DB::Network',
{
'foreign.address' => { '<=', 'self.address' },
'self.address' => \'<= (foreign.address - 1 + (2
<< 31 -
foreign.bits))'
},
{ join => [qw(network)] }
);
but it looks like DBIx::Class joins won't accept anything but /
^foreign./
named keys. Any ideas on how I could get something like this to
work?
Short answer: not easily in the current release.
Slightly longer answer: you can add a where => attr to your rel
defs, which
might get you a bit further. Also, I don't think that join => is doing
anything useful.
Long answer: This strikes me as the wrong solution - it doesn't
look like
it's really indexable so the join is going to be horribly
inefficient. Maybe
you'd be better off with a trigger that sets a parent field on
update, maybe
there's another way to denormalise this to be saner ... how about
storing
the top-end address as well so you can do it as a join with a
BETWEEN, thus
rendering it amenable to fairly quick lookup on a range index somehow?
So it turns out that if you have, say a bunch of networks stored like
this, getting the Children is pretty much impossible the way I was
trying to do this. I did what you said and I trigger an update of a
parent_id field on insert. And on the parent delete/update/insert
too of course. Works beautifully, much faster...
Now I just have to figure out why my prefetch isn't actually keeping
me from doing fewer DB queries. Thanks!
--
/chris/
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