Ruby on Rails

It would probably run a lot faster if you had a view and separate indexes on the two uid columns. I haven't got access to my MySQL at the moment, so i can't check the syntax for creating a view but you should be able to find that yourself. Something like:

CREATE VIEW friendshipview AS (<the union select statement>)

Creating separate indexes on the columns used in the select statements should speed things up quite a bit, an index should speed up by a factor of 10^2 or 3. If you have a very active database you might also consider rebuilding the index regularly, with OPTIMIZE TABLE <table name>.

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Fra: rubyonrails-talk@googlegroups.com [mailto:rubyonrails-talk@googlegroups.com] På vegne af Fresh Mix
Sendt: 22. december 2011 21:33
Til: rubyonrails-talk@googlegroups.com
Emne: [Rails] Re: SV: Simple friendship table

Brynjolfur Thorvardsson wrote in post #1037658:

> (SELECT uid2 AS uid, status FROM friendships WHERE uid1 = 1) UNION
> (SELECT uid1,status FROM friendships WHERE uid2 = 1)

It works fine, but it is slow :(

Only one entry per friendship (1 500 000 rows in database)

SELECT with UNION: 1.2108 sek

Dublicate entryes ( total 3 000 000 rows in database)

SELECT without UNION: 0.0007 sek

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