Moving pages is completely broken in 1.21wmf12
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	• Catrope
	Mar 21 2013, 2:00 AM

Description

Trying to move any page to a title that didn't previously exist causes an exception in 1.21wmf12.

I captured the following backtrace from nlwikimedia, using a debugging hack that includes $title->getPrefixedText() (which turned out to be the title the page was being moved to) in the exception message. I could also reproduce this my trying to move [[Test]] to [[Test2]] on test2.wikipedia.org .

2013-03-21 01:51:52 mw1055 nlwikimedia: [458e1031] /w/index.php?title=Speciaal:PaginaHernoemen&action=submit Exception from line 71 of /usr/local/apache/common-local/php-1.21wmf12/includes/LinksUpdate.php: The Title object for Wikimedia:De kroeg/Archief/2007 did not provide an article ID. Perhaps the page doesn't exist?
#0 /usr/local/apache/common-local/php-1.21wmf12/includes/parser/ParserOutput.php(474): LinksUpdate->__construct(Object(Title), Object(ParserOutput), true)
#1 /usr/local/apache/common-local/php-1.21wmf12/includes/content/AbstractContent.php(242): ParserOutput->getSecondaryDataUpdates(Object(Title), true)
#2 /usr/local/apache/common-local/php-1.21wmf12/includes/WikiPage.php(2066): AbstractContent->getSecondaryDataUpdates(Object(Title), NULL, true, Object(ParserOutput))
#3 /usr/local/apache/common-local/php-1.21wmf12/includes/Title.php(3847): WikiPage->doEditUpdates(Object(Revision), Object(User), Array)
#4 /usr/local/apache/common-local/php-1.21wmf12/includes/Title.php(3683): Title->moveToInternal(Object(Title), '', false)
#5 /usr/local/apache/common-local/php-1.21wmf12/includes/specials/SpecialMovepage.php(462): Title->moveTo(Object(Title), true, '', false)
#6 /usr/local/apache/common-local/php-1.21wmf12/includes/specials/SpecialMovepage.php(97): MovePageForm->doSubmit()
#7 /usr/local/apache/common-local/php-1.21wmf12/includes/SpecialPage.php(613): MovePageForm->execute(NULL)
#8 /usr/local/apache/common-local/php-1.21wmf12/includes/SpecialPageFactory.php(487): SpecialPage->run(NULL)
#9 /usr/local/apache/common-local/php-1.21wmf12/includes/Wiki.php(291): SpecialPageFactory::executePath(Object(Title), Object(RequestContext))
#10 /usr/local/apache/common-local/php-1.21wmf12/includes/Wiki.php(565): MediaWiki->performRequest()
#11 /usr/local/apache/common-local/php-1.21wmf12/includes/Wiki.php(458): MediaWiki->main()
#12 /usr/local/apache/common-local/php-1.21wmf12/index.php(59): MediaWiki->run()
#13 /usr/local/apache/common-local/live-1.5/index.php(3): require('/usr/local/apac...')
#14 {main}

Version: unspecified
Severity: critical

Details

Reference: bz46397

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Status	Assigned	Task
Declined	None	T45899 DataValues test failures
Resolved	None	T39209 LinkCache doesn't currently know about this title
Resolved	aaron	T48397 Moving pages is completely broken in 1.21wmf12

Event Timeline

• bzimport raised the priority of this task from to Unbreak Now!.Nov 22 2014, 1:35 AM

• bzimport added a project: MediaWiki-General.

• bzimport set Reference to bz46397.

• Catrope created this task.Mar 21 2013, 2:00 AM

If this isn't able to be fixed by tomorrow afternoon, let's roll back the wmf12 deploy.

Tim: Since you're awake first, can you debug and update us here, please?

Chris: Is this functionality covered in our test suite? If not, let's put it in the backlog.

On test2.wikipedia.org, moved "Title A" to "Title B". "Title A" now has an incorrect page_latest, an incorrect page_len, and an incorrect page_is_redirect:

mysql> select * from page where page_title = 'Title_A' and page_namespace = 0\G

1. row ******* page_id: 6762 page_namespace: 0 page_title: Title_A

page_restrictions:

page_counter: 0

page_is_redirect: 0

 page_is_new: 1
 page_random: 0.523019457806
page_touched: 20130321061504
 page_latest: 0
    page_len: 0

1 row in set (0.00 sec)

Bug 46403 has been marked as a duplicate of this bug. ***

This is most likely due to Iea16d672 (thanks Robla for pointing me in this direction).

Title::moveToInternal() moves the page and then calls $nt->resetArticleID($oldid) to reset the article ID. Then a new WikiPage is constructed with the title $nt, and updates are called on this WikiPage object. Before Iea16d672, $newpage->getId() would have returned the new ID due to it being stored in $nt->mArticleId, but after Iea16d672, $newpage->getId() calls $newpage->loadPageData(), which fetches the page_id from the *slave* database. Of course, it is not in the slave yet, since the update query and the select query are separated by microseconds.

It is easy to reproduce locally with $wgAllDBsAreLocalhost = true, with zero master load.

(In reply to comment #5)

It is easy to reproduce locally with $wgAllDBsAreLocalhost = true, with zero
master load.

That is to say, the update transaction is still open, so even a separate master connection does not see the new page_id. It's not necessary to actually have replication to see the issue.

I have rolled back all wikis to MW 1.21wmf11 and thus will lower the priority.

Also see https://gerrit.wikimedia.org/r/#/c/55017/