SQL大查询优化

Question

I have the following query:

SELECT `Product_has_ProductFeature`.`productId`, `Product_has_ProductFeature`.`productFeatureId`, `Product_has_ProductFeature`.`productFeatureValueId`
FROM `Product_has_ProductFeature`
WHERE `productId` IN (...'18815', '18816', '18817', '18818', '18819', '18820', '18821', '18822', '18823', '18824', '18825', '18826', '18827', '18828', '18829', '18830', '18831', '18832', '18833', '18834'..)

I have around 50000 productId's. The execution is 20 seconds long. How can I make it faster?

Answer 1

This is more of a comment.

Returning 50,000 rows can take time, depending on your application, the row size, the network, and how busy the server is.

When doing comparisons, you should be sure the values are of the same type. So, if productId is numeric, then drop the single quotes.

If the values are all consecutive, then eschew the list and just do:

where productid >= 18815 and productid <= 18834

Finally, an index on productid is usually recommended. However, in some cases, an index can make performance worse. This depends on the size of your data and the size of memory available for the page and data cache.

MySQL implements in efficiently (using a binary tree). It is possible that much of the overhead is in compiling the query rather than executing it. If you have the values in a table, a join is probably going to be more efficient.