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Editorial Team
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Asked: 2026-05-16T14:12:37+00:00

I have a query similar to this FROM products AS p, .. LEFT JOIN

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I have a query similar to this

FROM products AS p, ..
LEFT JOIN ( SELECT .. ) AS popularity on popularity.products_id = p.products_id
LEFT JOIN ( SELECT .. ) AS reviews on reviews.products_id = p.products_id
WHERE..
AND..
..

The nested SELECTs from the LEFT JOIN are static, I mean the returned result is not influenced by external values. Those two SELECTs use data from within the db and calculate a result. The results of these queries change rarely, when some user makes a review for a product for example.

The problem is that these SELECTs take a lot of time to complete, they go through each row of their respective tables.

Is there a way I could make this query faster by transforming it into several smaller queries? Or caching the nested selects in some way?

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1 Answer

  1. Editorial Team

    I agree it’s hard to answer without more information. However, check out this post: http://www.xaprb.com/blog/2006/04/30/how-to-optimize-subqueries-and-joins-in-mysql. I’ve found it quite helpful in the past.

    If you look at the very last paragraph, you’ll see a technique for saving results of the nested selects in a temporary table.

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