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by Conlectus
2030 days ago
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MySQL has worse guarantees in several cases, though. For example, using `SERIALIZABLE` isolation means your queries can deadlock when run in parallel. Likewise, selecting a column not present in a GROUP BY leads to random values being returned. |
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That hasn't been the default behavior for something like 5 years.
Beyond that the values aren't "random" as much as "one of the values from the set" which can be a useful feature in cares where you want any of the values and don't want the performance hit that comes with using an aggregate function particularly on very very large sets.