https://waylonwalker.com/tags/orm/atom.xml 2024-01-12T02:18:35Z All posts with the tag "orm" Waylon Walker markata-go https://waylonwalker.com/thought-195/ 2024-01-12T02:18:35Z 2024-01-12T02:18:35Z

!https://sqlmodel.tiangolo.com/tutorial/limit-and-offset/

<div class="embed-card embed-card-external"> <a href="https://sqlmodel.tiangolo.com/tutorial/limit-and-offset/" class="embed-card-link" target="_blank" rel="noopener noreferrer"> <div class="embed-card-image"> <img class="glightbox" src="https://sqlmodel.tiangolo.com/assets/images/social/tutorial/limit-and-offset.png" alt="Read a Range of Data - LIMIT and OFFSET - SQLModel — SQLModel, SQL databases in Python, designed for simplicity, compatibility, and robustness." loading="lazy"/ data-glightbox="description: Read a Range of Data - LIMIT and OFFSET - SQLModel — SQLModel, SQL databases in Python, designed for simplicity, compatibility, and robustness."> </div> <div class="embed-card-content"> <div class="embed-card-title">Read a Range of Data - LIMIT and OFFSET - SQLModel</div> <div class="embed-card-description">SQLModel, SQL databases in Python, designed for simplicity, compatibility, and robustness.</div> <div class="embed-card-meta">sqlmodel.tiangolo.com</div> </div> </a> </div> <p>Today I was running some sqlmodel queries through the sqlalchemy orm. Admittedly I’ve not done enough orm queries before, and I’ve done quite a bit of raw sql. I was trying to get objects from two separate models that had relationships setup.</p> <pre class="chroma"><code><span class="line"><span class="cl"><span class="n">session</span><span class="o">.</span><span class="n">query</span><span class="p">(</span><span class="n">User</span><span class="p">,</span> <span class="n">Images</span><span class="p">)</span><span class="o">.</span><span class="n">where</span><span class="p">(</span><span class="n">User</span><span class="o">.</span><span class="n">id</span> <span class="o">==</span> <span class="mi">3</span><span class="p">)</span><span class="o">.</span><span class="n">all</span><span class="p">()</span> </span></span></code></pre><p>It is incredibly slow, and gives me the following warning.</p> <pre class="chroma"><code><span class="line"><span class="cl"><span class="n">SELECT</span> <span class="n">statement</span> <span class="n">has</span> <span class="n">a</span> <span class="n">cartesian</span> <span class="n">product</span> <span class="n">between</span> <span class="n">FROM</span> <span class="n">element</span><span class="p">(</span><span class="n">s</span><span class="p">)</span> </span></span></code></pre><p>What I learned from the SQLModel docs is that you should give it a join to correct this and go much faster.</p> <pre class="chroma"><code><span class="line"><span class="cl"><span class="n">session</span><span class="o">.</span><span class="n">query</span><span class="p">(</span><span class="n">User</span><span class="p">,</span> <span class="n">Images</span><span class="p">)</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">Images</span><span class="p">)</span><span class="o">.</span><span class="n">where</span><span class="p">(</span><span class="n">User</span><span class="o">.</span><span class="n">id</span> <span class="o">==</span> <span class="mi">3</span><span class="p">)</span><span class="o">.</span><span class="n">all</span><span class="p">()</span> </span></span></code></pre><div class="admonition note"> <p class="admonition-title">Note</p> <p>This post is a <a href="/thoughts/" class="wikilink" data-title="Thoughts" data-description="These are generally my thoughts on a web page or some sort of url, except a rare few don&#39;t have a link. These are dual published off of my..." data-date="2024-04-01" data-preview="These are generally my thoughts on a web page or some sort of url, except a rare few don&#39;t have a link. These are dual published off of my...">thought</a>. It’s a short note that I make about someone else’s content online <a href="/tags/thoughts/" class="hashtag-tag" data-tag="thoughts" data-count="2" data-reading-time="3" data-reading-time-text="3 minutes">#thoughts</a></p> </div> Waylon Walker hello@waylonwalker.com https://waylonwalker.com