get page id's - not get pages?

Question

I'm trying to do something like this: Hide a page in the admin end without a plugin?

However, I don't want to hardcode the page-ids. I want to get the page id's based on template-name.

$pages = get_posts(array(
        'post_type' => 'page',
    'meta_key' => '_wp_page_template',
    'meta_value' => 'product.php'
)); 

^^This probably does the job, but it gets entire pages, and I start worrying about efficiency, especially when I only need id's and there could be thousands of pages being returned by this command.

I know SQL pretty well, so if I should just write my own query, then let me know.

Or maybe I don't need to worry about this at all?

Answer 1

Use the parameter 'fields':

$pages = get_posts(
    array(
        'post_type'  => 'page',
        'meta_key'   => '_wp_page_template',
        'meta_value' => 'product.php',
        'fields'     => 'ids'
    )
); 

Not tested, but it should fetch just the IDs.