Get the post permalink within the loop but without additional DB query

I notice that to link to each post, I am calling get_permalink() and this is creating an extra DB query for each post.

Not true. If you check the link to the very old trac ticket #18822 in the post that you have linked to, this issue was raised by @kaiser in 2011. The question was answered by @scribu

For example:
$posts = get_posts();
foreach ( $posts as $post )
    var_dump( get_permalink( $post->ID ) );
will not cause extra queries as all those posts are cached. You can
also pass the whole $post object to get_permalink for no extra queries
as get_post() accepts an object. In fact get_post() will only perform
a query if you pass an object when the object has the filter property
set and that post ID isn’t already cached.

As always, I do not go on theory, but on facts, and the way I get my facts is in testing

Set yourself up with the following query and run it, and note the time and db calls

timer_start();  
$posts = get_posts();
foreach ( $posts as $post ) {

    // REST TO COME LATER

}
echo '<p>' . get_num_queries() . ' queries in ' . timer_stop(1, 5) . ' seconds. </p>';

On my local install I get the following results:

20 queries in 0.02539 seconds

(NOTE: The amount of queries is not just for the query, but the total amount of queries that run on the page, this included menus, widgets, custom queries, main query etc. Times may vary on every page load)

Now, change the query as indicated below

timer_start();  
$posts = get_posts();
foreach ( $posts as $post ) {

    get_permalink( $post->ID );

}
echo '<p>' . get_num_queries() . ' queries in ' . timer_stop(1, 5) . ' seconds. </p>';

And this is my result

20 queries in 0.02539 seconds.

As you can see, and as I have proved, the cache is first check before making a query as described in the trac ticket.

CONCLUSION

You can use get_permalink() and you don’t have to worry about extra db calls due the cache system in WordPress. You should take your time as well and work through the trac ticket

CONCLUSION

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