Christopher Browne wrote:

>If horarios_general is a table of millions of entries, where thousands
>get updated each hour, 
>
i dont think so...

>there is sense in agonizing over whether or not
>to add a serial column as a surrogate primary key.
>If, on the other hand, it's going to have a few rows modified per day,
>it isn't worth thinking too hard about it, and the difference between
>a single serial PK and a composite of his six columns will be
>immaterial.
>  
>
Im pretty sure this will be the case, in fact, i will be inserting few 
rows per week,
its good to know the details though.

thanks
---
miguel