DB schema clean-ups

[Denis-de-Bernardy]

While looking into #9422, it occurred to me that some DB fields weren't necessarily used today. Namely:

links.link_category int(20) seems to be overridden by the terms schema.

The same goes for posts.post_category int(4).

It might be that they've been left around for obsolete plugins, though. In case this isn't the case, the attached patch, for 2.8 trunk, will remove them.

Marking as needs-testing, in case their absence has any impact I've missed by scanning the source code.

use int(11) rather than bigint(20) unsigned, for smaller indexes (and thus faster queries)

more relevant text fields: text is 65kb, mediumtext is 16MB, longtext is 4GB - an rss field stored in wp_options is only rarely larger than 65kb, and no post would ever be larger than 16MB

the same patch, keeping comment_author and post_title as text fields in case this was needed for any reason

smaller int fields. surely no post will have over 65k comments?

drop user_status field -- see ​http://comox.textdrive.com/pipermail/wp-hackers/2009-January/023550.html

(In [10895]) Drop post_category and link_category from the schema. Props Denis-de-Bernardy. see #9435

Is this correct?

By dropping post_category and link_category, new installs will not see those columns, but upgraded databases will still have the two columns.

Correct. dbDelta() doesn't handle deleting old columns.

user_status, BTW, is needed by bbPress.

I take it the other ones are not to be used? close as fixed, or move to 2.9 for the text/varchar/int cleanups?

2.9 sounds good for the type cleanups.