Recent comments widget triggers query for each post not in cache

[nacin]

Ideally, we should reduce this to a single query.

[scribu]

Sorry, I misread the 3.1 schedule. This can still go in until Nov. 15.

[jane]

Punting due to beta.

[westi]

I think in general this Widget makes too many queries as we also run queries for all the links to work out which page the comments are on when comment paging is enabled.

[chalet16]

patch

[chalet16]

More safety patch (add and also remove object cache)

[westi]

I've reviewed your patch and have the following comments.

1. You shouldn't directly access/delete cache objects from within the widget code
2. It would be better to do two queries one to fetch the comments and one with get_posts to fetch and cache the posts.

[westi]

Patch from ​http://www.google-melange.com/gci/task/show/google/gci2010/wordpress/t129162975592

[westi]

Another patch from ​http://www.google-melange.com/gci/task/show/google/gci2010/wordpress/t129162975592

[nacin]

We can now use _prime_post_caches() here.

[mitchoyoshitaka]

Quick patch using _prime_post_caches

[nacin]

A term cache *might* be necessary if the permalink has term structures like %category%. I'm fine with the patch as is, but something to think about.

[mitchoyoshitaka]

I propose that we open another ticket to create something like a permalinks_include_terms() function (which may have other uses elsewhere?), but otherwise land this for the time being. Nacin, thoughts?

[nacin]

Replying to westi:

I think in general this Widget makes too many queries as we also run queries for all the links to work out which page the comments are on when comment paging is enabled.

I forgot about this part.

[nacin]

Let's at least get _prime_post_caches() in for 3.4. I am thinking we do this as a play-it-safe:

_prime_post_caches( $post_ids, strpos( get_option( 'permalink_structure' ), '%category%' ), false );

[nacin]

And by 3.4, I mean 3.5. Tough to keep track these days.

[nacin]

In [22278]:

Prime post caches for the Recent Comments widget. props mitchoyoshitaka. see #15400.

[nacin]

Opened #22261 for pagination-related queries.