PostgreSQL's `DISTINCT ON` extension is useful for navigating bitemporal data in... | Hacker News

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		ryandv 73 days ago \| parent \| context \| favorite \| on: SQL Anti-Patterns PostgreSQL's `DISTINCT ON` extension is useful for navigating bitemporal data in which I want, for example, the latest recorded version of an entry, for each day of the year. There are few other legitimate use cases of the regular `DISTINCT` that I have seen, other than the typical one-off `SELECT DISTINCT(foo) FROM bar`.

dotancohen 73 days ago [–]

Without DISTINCT ON (which I've never used) you can use a window function via the OVER clause with PARTITION BY. I'm pretty sure that's standard SQL.

ryandv 73 days ago | [–]

Yes, this is the implementation I have seen in other dialects.

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