Am 17.07.19 um 14:48 schrieb Tomas Vondra:
> Either that, or try creating a covering index, so that the query can
> do an
> index-only scan. That might reduce the amount of IO against the table,
> and
> in the index the data should be located close to each other (same page or
> pages close to each other).
>
> So try something like
>
> CREATE INDEX ios_idx ON table (field, user_id);
>
> and make sure the table is vacuumed often enough (so that the visibility
> map is up to date).
yeah, and please don't use varchar(64), but instead UUID for the user_id
- field to save space on disk and for faster comparison.
Regards, Andreas
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