Add blog author data near top of export file

[briancolinger]

Reading WXR to find post authors is slow. The entire file has to be scanned to find all authors.
Putting them near the top of the file would allow the importer to read the user list without having to scan the entire file.
I've attached a patch to enable this.

[briancolinger]

re-structuring the xml tags for users

[briancolinger]

Changed the XML tags to follow convention.
<wp:users> root tag for containing users.
<wp:user> tag to contain each user record.

[dd32]

Is this used by the importer at present? Or is this for non-WP platforms?

[xibe]

Indeed. It's one thing to change the export format, it's another to allow the importer to use it properly.

[briancolinger]

No, the importer does not read this format yet. I can make a patch for the importer check the version of the WXR, then use the data if it is present.

[dd32]

Patch review:

• Would SELECT DISTINCT perhaps be better than a GROUP BY?
• <wp:users> might not be the best naming, since it only contains post authors, <wp:authors> might suit better?
• Seems putting it in a <wp:users> is out of sync with the file, It holds everything as a flat index, ie. <wp:user>....</wp:user><wp:user>....</wp:user>, Without a wrapper around it all.

[Denis-de-Bernardy]

other notes:

• get_results(select *) rather than a get_col(select id) would be sweeter. then we fill the cache so as to avoid a zillion queries on sites with multitudes of authors
• also, it's important to only retrieve post authors (possibly comment authors as well?), rather than all users from an entire WPMU install
• importer most welcome too

[briancolinger]

I've made some of the suggested changes to the export patch. As far as the importer changes go, I would like to get these exporter changes finalized first.

[nacin]

(In [15961]) Importer and exporter overhaul, mega props duck.

Exporter overhaul:

• Add author information to export
• Greater usage of slug identifiers
• Don't export auto-drafts, spam comments, or edit lock/last meta keys
• Inline documentation improvements
• Remove filtering for now (@todo)
• Bump WXR version to 1.1, but remain back compat in the importer

Importer overhaul (​http://plugins.trac.wordpress.org/changeset/304249):

• Use an XML parser where available (SimpleXML, XML Parser)
• Proper import support for navigation menus
• Many bug fixes, specifically improvements to category and custom taxonomy handling
• Better author/user mapping

Fixes #5447 #5460 #7400 #7973 #8471 #9237 #10319 #11118 #11144 #11354 #11574 #12685 #13364 #13394 #13453 #13454 #13627 #14306 #14442 #14524 #14750 #15055 #15091 #15108.

See #15197.