Shawn Marincas wrote:
> It seems that the above query won't work in any case since searching
> for tag_id IN a set will still returned the results OR'd together, and
> I need the set of products which contain BOTH tags. I've been toying
> with it some more and came up with a solution which uses a subquery,
> still not sure if this is the optimum solution yet or not.
If you're worried about optimization, the one thing I would watch for is
to ensure that the DBMS is still able to optimize the subquery by
determining the most restrictive initial set of data, or otherwise
implementing that optimization manually. With something like tags I
would assume that some are far more general than others so this could
have a significant impact. This is something that would normally occur
with a self-join, but a subquery is likely a more fitting solution in
your case.
I may also suggest coupling this with a digest form of the tags (similar
to a SET data type) which can then be run through a bitwise AND. This
would require organizing the tags (possibly into word-sized categories)
but should allow for very quick checks that wouldn't add overhead as
searches grew more complex.
>
> $filtered_product_rs = $schema->resultset('Product')->search({
> 'product_tags.tag_id' => $tag2_rs->tag_id,
> 'me.product_id' => {
> -in => [
> $schema->resultset('Product')->search_rs({
> 'product_tags.tag_id' => $tag_rs->tag_id
> },{
> join => 'product_tags'
> })->get_column('product_id')->all
> ]
> }
> }, {
> join=> 'product_tags'
> });
>
>
> On Fri, Sep 18, 2009 at 7:35 PM, Wallace Reis <
[hidden email]
> <mailto:
[hidden email]>> wrote:
>
> On Fri, Sep 18, 2009 at 3:06 PM, Shawn Marincas
> <
[hidden email] <mailto:
[hidden email]>> wrote:
> > I have a table Products and a table Tags with a many_to_many
> relationship
> > setup, the purpose of which would be to easily generate a
> resultset of
> > products with the given tag(s). However, I'm running in to
> problems when I
> > want to generate a resultset of product records filtered with
> multiple
> > tags. I was thinking that one of the following would work:
> >
> > my $tag1 = 'A';
> > my $tag2 = 'B';
>
> my $product_rs = $schema->resultset('Product')->search_rs({
> 'tag.tag_id' => { -in => [qw/A B/] }
> }, {
> join => { 'product_tags' => 'tag' }
> });
>
> > But apparently the many_to_many relationship accessor only
> returns a list of
> > row_objects rather than a resultset itself, so I can't perform
> resultset
> > searches on that. So I tried the following to chain together
> two searches:
>
> You've used the ->search method in your code in list context, so it
> calls ->all over the resultset and returns a list of row objects.
>
> --
> wallace reis/wreis Catalyst and DBIx::Class
> consultancy with a clue
> Software Engineer and a commit bit:
>
http://shadowcat.co.uk/catalyst/> Shadowcat Systems Limited
>
http://www.shadowcat.co.uk http://www.linkedin.com/in/wallacereis>
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