Re: Slow query with a lot of data

[Moritz Onken <onken@xxxxxxxxxxxxxxxx>]

> >
>
> Well, you're getting the database to read the entire contents of the  
> domain_categories table in order. That's 12 million rows - a fair  
> amount of work.
>
> You may find that removing the "user = 1337" constraint doesn't make  
> the query much slower - that's where you get a big win by clustering  
> on domain. You might also want to cluster the results table on domain.

Running the query for more than one user is indeed not much slower.  
That's what I need. I'm clustering the results table on domain right  
now. But why is this better than clustering it on "user"?

> If you want the results for just one user, it would be very helpful  
> to have a user column on the domain_categories table, and an index  
> on that column. However, that will slow down the query for all users  
> a little.

A row in domain_categories can belong to more than one user. But I  
don't need to run this query for only one user anyway.

Thanks so far,