What is considered a default query for the request filter?

As stated in one of the answers in this question and in the codex entry for the request filter, said filter gets called only in a default query, such as the main query used for a loop. My question is, what else is or isn’t considered a default query? Would creating a new WP_Query object be considered such?

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The “default” query is the one WordPress does itself, based on the URL and such, automatically.

Any query you create manually, via a new WP_Query or by calling query_posts(), will not use the ‘request’ filter.

There is only one “default” query, and you cannot trigger it via any code in the template.

request is only applied once, by parse_request(), a method of the WP class. There is only one reference to this, it is by another method of WP, main(). main() is referenced one time, by wp(). wp() is referenced in a few different contexts by a number of different functions and files: wp_trackback.php, get_feed(), wp-blog-header.php, wp_edit_posts_query(), and wp_edit_attachments_query(). So, looking through that, nothing that `WP_Query calls is listed.

Short answer: I’d say no, it does not call request.

All that said, my work is based on working backwards with phpxref (hence the links), so I may have missed something, or it may have missed something. A better way to ask your question might be to ask on what you’re trying to do, not on your implementation of it.

Just a note: main() does call query_posts(), which (I think) does the default query and such, but an instance of WP_Query alone shouldn’t be enough to trigger this from what I’ve seen.