In my case:
https://dba.stackexchange.com/q/325355/118215
I have a table:
create table "appointments"(
id SERIAL PRIMARY KEY,
client_id INTEGER NOT NULL,
appointment_timestamp TIMESTAMP WITHOUT TIME ZONE NOT NULL,
store_id INTEGER NOT NULL,
CONSTRAINT fk_user FOREIGN KEY(client_id) REFERENCES "client"(id),
CONSTRAINT fk_store FOREIGN KEY(store_id) REFERENCES "store"(id)
);
I want in it to find the most recent appointment in appointments for each user. An approach of mine is to use a lateral join:
select
*
from
"client"
left join lateral (
select
*
from
appointments join store on appointments.store_id = store.id
where appointments.client_id = client.id
order by appointment_timestamp DESC
limit 1
) as latest_appointment on true
But seems kinda slow to me. Is there a way to speed it up?
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