Databases
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  1. PO
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    <p>Actually, select_related is what you are looking for. select_related creates a JOIN so that all the data that you need is fetched in one statement. prefetch_related runs all the queries at once then caches them.</p> <p><strong>The trick here is to "join in" only what you absolutely need to in order to reduce the performance penalty of the join.</strong> "What you absolutely need to" is the long way of saying that you should pre-select only the fields that you will read later in your view or template. There is good documentation here: <a href="https://docs.djangoproject.com/en/1.4/ref/models/querysets/#select-related" rel="nofollow">https://docs.djangoproject.com/en/1.4/ref/models/querysets/#select-related</a></p> <p>This is a snippet from one of my models where I faced a similar problem:</p> <pre><code>return QuantitativeResult.objects.select_related( 'enrollment__subscription__configuration__analyte', 'enrollment__subscription__unit', 'enrollment__subscription__configuration__analyte__unit', 'enrollment__subscription__lab', 'enrollment__subscription__instrument_model' 'enrollment__subscription__instrument', 'enrollment__subscription__configuration__method', 'enrollment__subscription__configuration__reagent', 'enrollment__subscription__configuration__reagent__manufacturer', 'enrollment__subscription__instrument_model__instrument__manufacturer' ).filter(&lt;snip, snip - stuff edited out&gt;) </code></pre> <p>In this pathological case, I went down from 700+ queries to just one. The django debug toolbar is your friend when it comes to this sort of issue.</p>
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    1. POList of parents objects and their children with fewer queries
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    1. USNgure Nyaga
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    1. COThat's an impressive query reduction! But does `select_related` allow following a foreign key in the 'reverse' direction? (I agree that django debug toolbar is a invaluable tool...)
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    2. COI was not able to follow a FK in the reverse direction. In one troublesome case, I had to fall back to raw SQL ( with the attendant loss of portability )
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Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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