Change Attribute Some Links on Content - php

Question

I'm building plugin wordpress for change attribute some links on content of post. I have function like this :
public static function encrypt_link_content( $content ){
if ( strpos( $content, 'safelinkThis' ) !== false ) {
// get dom from string of content
$content = str_get_dom($content);
// find link with attribute data-role=safelinkThis
$all_links = $content('a[data-role=safelinkThis]');
$count_links = count($all_links);
$i = 0;
$_links = self::get_links_post($count_links);
foreach ($all_links as $a) {
$href = $a->href;
$encrypt = self::zi_encrypt($href);
$a->href = $_links[$i]."?link=".$encrypt;
$i += 1;
}
$content = (string) $content;
}
return $content;
}
That function is work, Attribute href of link have been changed.
example of content :
Find us on :
Go to facebook
Go to google
Go to Twitter
Will be change to like this :
Find us on :
Go to facebook
Go to google
Go to Twitter
I'm use http://code.google.com/p/ganon/ library to find dom in string.
Now
I have a custom table for store domain exception, The name is wp_sf_domain. I won't change a link if it have href attribute with domain exception from wp_sf_domain.
I know, I can use this
global $wpdb;
$sf_table_name = $wpdb->prefix . 'sf_domain';
foreach ($all_links as $a) {
$href = $a->href;
$aDomain = parse_url($href)['host'];
$record = $wpdb->get_results( "SELECT * FROM $sf_table_name WHERE domain='$aDomain'" );
if(count($record) == 0){
// change this link
}
}
But I think this is a bad practice if I have many links on content, I should check one by one to database.
How can I compare between host of link on content with list domain in database and change a link attribute href if host of link not include in database?