Twenty Fourteen: reduce the number of queries when there is no featured post

[Chouby]

Thanks to the transient used by Feature_Content::get_featured_post_ids, the featured post ids are not queried at each page load. The transient is however never set if there is no featured post resulting in performance loss.

[Chouby]

according to my tests, the proposed patch suppresses 6 queries

[obenland]

If we trust our cache busting enough, we could just put those sticky post ids in the transient, if there are no tagged posts. ;)

[lancewillett]

@obenland Want to look at this one again?

[ryanshoover]

@obenland's patch works great for me.
No featured posts:
26 queries dropped to 24 queries with the patch

1 featured post:
54 queries dropped to 29 queries

Minor gain when there are no featured posts, significant gain with featured posts.

[lancewillett]

Saw a problem in testing: $featured = get_posts( array() ); the variable assignment here should be $featured_ids instead, right?

[obenland]

Replying to lancewillett:

the variable assignment here should be $featured_ids instead, right?

Correct, good catch.

[lancewillett]

This is my testing results with the updated patch:

With no featured posts:
34 queries on first load, down to 26 queries on second load

With featured posts:
43 queries on first load down to 35 on second load

(Using Debug Bar plugin with define( 'SAVEQUERIES', true ); in my wp-config.php file.)

[lancewillett]

Use correct variable for featured IDs

[lancewillett]

In 29174:

Twenty Fourteen: optimize featured content lookup to reduce the number of queries for featured posts. Props Chouby and obenland, closes #26744.

[afercia]

hi Lance, all,
did you consider to use WP_Query in combination with update_post_thumbnail_cache() instead of get_posts? I wonder why update_post_thumbnail_cache() is a bit obscure and not documented in the Codex, is it still recommended? Read about it in #19949 and looks like a great way to reduce queries when there are many thumbnails to get at once. With 6 featured posts and 6 thumbnails could save 10 queries.
However, it would require to change something also in Jetpack.