Optimizing SQL JOIN query

Question

I have two database table 'friends' and 'published_post'

`friends` --- contains 650K rows 
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| fb_id_user(bigint)  |   fb_id_friend(bigint) | fb_username(text) |
---------------------------------------------------------


`published_post` ----- contains 6K rows
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| id(primary_key)(int)  |   fb_id(bigint) | post(text) |  post_date(DATE_TIME) |
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suppose a user has facebook id '12345'. I want to get all the post(form published_post table) given by his friends(from friends table where fb_id_user = '12345') in descending order of 'post_time'. Any suggestion how this query can be done efficiently would be very helpful.

Answer 1

SELECT
    pp.*
FROM published_post pp
LEFT JOIN friends f ON f.fb_id_user = pp.fb_id
WHERE pp.fb_id_friend = '12345'
ORDER BY f.post_date DESC