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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