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Re: Query optimize on large database
Posted by: Pavel Volkov
Date: July 18, 2016 04:28AM

Yeah, there's a typo in my 1st post query. (group by d1.owner_id must be d2.owner_id)

Ofc, the correct one is:

SELECT d2.owner_id, COUNT(*) AS kolvo
FROM data d1
JOIN data d2 USING(Artist,Title)
WHERE d1.owner_id = @user_id
GROUP BY d2.owner_id

Again - structure is [owner_id, Artist, Title]. More than 100 000 users there.

Requirement is to get number of songs matching the specified user's songlist and group it by other user's with indicating the number of matches.

For example we got @user_id = 123 at the input, so we must get list like

[owner_id , matches]

2: 5
52: 4
74: 2
433: 10
... and so on doing fullscan

Sorry for maybe not so PLAIN english :)

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