Re: Best method to compare subdomains

On 2013-01-16, Robert James <srobertjames(at)gmail(dot)com> wrote:
> Is there a recommended, high performance method to check for subdomains?
>
> Something like:
> - www.google.com is subdomain of google.com
> - ilikegoogle.com is not subdomain of google.com
>
> There are many ways to do this (lowercase and reverse the string,
> append a '.' if not there, append a '%', and do a LIKE). But I'm
> looking for one that will perform well when the master domain list is
> an indexed field in a table, and when the possible subdomain is either
> an individual value, or a field in a table for a join (potentially
> indexed).

write a function that does the string mangling you describe above and
then index on the result.

then you can use like and the index will help.

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