Tag: UNION
UNION ALL, data types and performance
© Laurenz Albe 2022 A while ago, I wrote about the performance impact of query parameter data types. Recently I encountered a similar problem with UNION ALL that baffled me for a while, so I’d like to share it with you. UNION ALL to implement polymorphism Different entities can have something in common. For example, […]
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Rewrite OR to UNION in PostgreSQL queries
Rewriting OR is not always the best solution © Laurenz Albe 2022 In my article that reviles OR, I showed how in certain cases, it is possible to rewrite OR in a WHERE condition to a longer query with UNION that can perform much better (the “ugly” OR). Now people have asked me repeatedly why […]
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