I'm getting an error message similar to an earlier message,
http://lists.scsys.co.uk/pipermail/dbix-class/2014-August/011746.html
I've got code like this:
$planet_rs =
Lacuna->db->resultset('Map::Body')->
search(
{
'sitterauths.sitter_id' => $real_empire->id,
'me.class' => { '!=' =>
'Lacuna::DB::Result::Map::Body::Planet::Station' },
},
{
join => { empire => 'sitterauths' },
prefetch => 'empire',
order_by => ['me.name'],
});
It's giving me the same error:
DBIx::Class::ResultSet::_construct_results(): Unable to properly collapse
has_many results in iterator mode due to order criteria - performed an eager
cursor slurp underneath. Consider using ->all() instead at /data/Lacuna-
Server/lib/Lacuna/DB/Result/Empire.pm line 622
The earlier message implied that it would be fixed in 0.082700_05, but I'm
using 0.082810 at the moment. So, either it wasn't fixed, or I'm encountering
something different.
Further searching uncovers
https://www.mail-archive.com/dbix-class@lists.scsys.co.uk/msg07082.html - in
which Peter Rabbitson indicates
that I would 'need to order_by "leftmost part" for this message to go away' --
but I don't understand what "leftmost part" means in this context.
If it helps, Map::Body has 0 or 1 empires (can be null), and sitterauths has a
dual-column primary key, referring to two empire through their IDs. So, while
ordering by empire is neither helpful nor hurtful to me, ordering by
sitterauth makes no sense (though it will likely not harm me, either, if I
sort in there). However, I've tried an order_by of [ 'empire.id', 'me.name'
], or even [ 'empire.id','sitterauths.sitter_id','me.name' ], and still end up
with the error message.
I'm expecting that once I roll this out into production and it gets wide use,
we'll have a thousand rows ("Map::Body" objects) being returned, and up to 40
or 50 empires, so I'd rather not resort to ->all to save some memory in the
Plack processes.
Any guidance on how to update this order_by to get DBIC to only fetch one row
at a time would be appreciated.
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