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Re: Left Join with Limit 1

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Running the queries individually and using a limit on the golite ip db
results are back immediately 1-2ms but when using the first query it
takes 2-3 seconds.

Is there a way to use a limit in the join?

This sounds like the real issue is a missing/incorrect index, but if you're on 9.4+ you can use a lateral join like this:


SELECT S.referrer_ip,
       I.geoname_id
FROM viewing_stats AS S
LEFT JOIN LATERAL (
    SELECT *
    FROM geolite_city_ip4
    WHERE S.referrer_ip::inet <<= network
    LIMIT 1
) I
ON true
WHERE viewing_id=74;

You might also want some kind of ordering in that subquery so that the results are deterministic.


Paul


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