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    <p>I don't know if it will solve you problem but for complex queries like that I almost always just use <a href="https://github.com/ernie/squeel" rel="nofollow">Squeel</a>.</p> <p>Then do something like this:</p> <pre><code>@posts = Post.joins(:tags) .where{tags.name.like_any names_array} .group("post_id") .having("count(post_id) = #{names_array.size}") </code></pre> <p>The SQL hopefully looks something like this</p> <pre><code>SELECT "posts".* FROM "posts" INNER JOIN "tags" ON "tags"."post_id" = "posts"."id" WHERE (("tags"."name" LIKE "TagA" OR "tags"."name" LIKE "TagB")) GROUP BY post_id HAVING count(post_id) = 2 </code></pre> <p>If I remember squeel is pretty good at using ILIKE instead of LIKE depending on the database used. (atleast better than AR)</p> <p>Also you could do this using AR without <a href="https://github.com/ernie/squeel" rel="nofollow">squeel</a> but I REALLY like some of the ideas and helpers that come with <a href="https://github.com/ernie/squeel" rel="nofollow">squeel</a> like <code>_all</code></p> <hr> <p>As for an explination...</p> <p>Assume I searched for TagsA and B.</p> <p>What that does is finds all the Posts with those tags.</p> <p>So you'll have something like:</p> <ul> <li>PostA TagA</li> <li>PostA TagB</li> <li>PostB TagA</li> <li>PostB TagB</li> <li>PostC TagA</li> </ul> <p>Then it will group all those different Post results by the joined tags using post_id.</p> <ul> <li>PostA TagA TagB</li> <li>PostB TagA TagB</li> <li>PostC TagA</li> </ul> <p>Then it will check the number of Tags the SQL line has by checking how many forgien_ids are present. Since A and B have 2 tags you know it matched all you input.</p>
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    1. COThanks a lot, the code looks much cleaner with squeel. Do you know if squeel has any impact on the query performance ?
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    2. COI'm pretty sure there isn't, but I can't guarantee it.
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