0 sats \ 4 replies \ @Lumor 14 Jul 2023 \ on: That moment when you increase query performance by 600x by adding two characters tech
Sheesh. Care to name the guilty SQL implementation?
Postgres 14.7
To be fair, it's understandable that postgres doesn't know that
extract(epoch from ts) does not change the order of m.ts.
For postgres, it's just a random function which could do anything, I guess. So it can't use the index since it needs to calculate that value for every row first. To spot stuff like this is part of my job as a developer :)reply
Ah, yeah, I guess "overwriting" with "AS ts" in this case would understandably cause such issues, missed that detail. Well done finding it. 🙂
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It would be the same on any implementation IMHO. At least it's the same with MySQL too.
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Yeah, overwriting field names should be avoided if possible.
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