Postgres SELECT DISTINCT Does Not Scale(dbos.dev) |
Postgres SELECT DISTINCT Does Not Scale(dbos.dev) |
Postgres doesn't have it yet https://wiki.postgresql.org/wiki/Loose_indexscan
Correct. This is documented in depth: DISTINCT sorts the results first.
The article's use case seems to imply the author did not know about GROUP BY, nor does it imply the author knew about indexes, nor ANALYZE. Postgres 18's new skip scan indexing also could help here, so ensuring the planner chooses that could help.
The article explains that skip scan doesn't do anything here.
> nor does it imply the author knew about indexes, nor ANALYZE
Indexes were talked about a lot, and they explicitly mentioned looking at the query plan.