Ok! I've implemented the indexes and things are now warp speed! Mysql is great, I was the one screwing up... lghs. Also because I was imposing a conversion to binary of all the fields, to make sure the different cases werenīt ignored when comparing similar records:

select pivot.received_id 
from catalog inner join pivot on 
( binary catalog.author = binary pivot.author and 
binary catalog.titulo = binary pivot.titulo and 
binary catalog.label = binary pivot.label and 
binary catalog.description = binary 
pivot.description and 
binary catalog.price = binary pivot.price );
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Iīve put the indexes and things didnīt get any better. Then I decided to get less perfectionist, and took away all the binaries... ok, mysql, no problem, ths isnīt really thaaaat necesary for me. Well, then the join that was taking 3 minutes, surprised me with the output screen in, guess what, 1 second!

Thanks for all the inputs, my fellow coders.And sorry for not having mentioned this 'binary' issue, as I thought it might not be it. But as you directed me to the only one thing that could explain the slowness, and it didnīt solve it, I could start suspecting about the binary.

Take care

Andre