[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2011-07-08 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

Dan Collins  changed:

   What|Removed |Added

 Status|NEW |RESOLVED
 CC||en.wp.s...@gmail.com
 Resolution||FIXED

--- Comment #34 from Dan Collins  2011-07-09 02:55:42 UTC 
---
It seems that between Tim and Ariel the repair scripts have been run and all
test cases except the most recent one referenced to bug 8689, however that bug
has been  resolved, and the referenced revision text appears to be available.
Marking this as fixed?

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-05-28 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

--- Comment #33 from Derk-Jan Hartman  2010-05-28 
14:34:58 CEST ---
Ariel, can you check 44320111 from bug 8689 against that list ?

Perhaps the list of unrecoverable revisions be added to the ticket or something
? That would help match any other cases we find against this problem and help
finding issues that are something other than this problem.

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-05-27 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

--- Comment #32 from Ariel T. Glenn  2010-05-28 06:09:52 
UTC ---
(In reply to comment #31)

According to the fixup script, those revisions are unrecoverable. 

I had a look at a few random revisions 9752546, 11243046, 11397897 from the
time period you mentioned. The text pointer for these revisions goes to a
single location in cluster5, with the same id and itemid.  I seem to be able
retrieve something from there manually, plugging the pointer into
ExternalStore::fetchFromUrl(), but it's one text item, not a concatenated set
of texts.  I can't say if your history unmerge had anything to do with it.

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-05-27 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

--- Comment #31 from Graham87  2010-05-28 02:58:51 UTC ---
The bug is almost resolved, then. I'm still curious about the problem with the
plasma article that I described in comment 29; it turns out to affect all edits
from 12:22, 28 January 2005 (UTC_) to 00:00, 16 April 2005 (UTC). I'd like to
know whether (a) it is a result of this bug and (b) whether the affected
revisions are recoverable.

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-05-27 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

Ariel T. Glenn  changed:

   What|Removed |Added

 CC||ar...@wikimedia.org

--- Comment #30 from Ariel T. Glenn  2010-05-28 02:40:33 
UTC ---
So Tim ran the fixup script on all other wikis on Feb 27th and none of them
were affected.  I don't know if there is anything else that needs to be checked
before this bug is closed, though.

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-03-31 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

--- Comment #29 from Graham87  2010-03-31 14:42:47 UTC ---
Does this error message at the plasma page have anything to do with bug 20,757,
or the fix for it:
http://en.wikipedia.org/w/index.php?title=Plasma&oldid=9752546

I undid a braindead history merge from "plasma" to "plasma physics", before the
script was run in the English Wikipedia. Since the history merge tangled many
edits together from January 2005, I wonder if my machinations at the plasma and
plasma physics pages in January 2010 caused something to break.

I'm fairly sure that the above revision was visible before I untangled the
history at plasma physics.

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-02-11 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

--- Comment #28 from Tim Starling  2010-02-12 00:13:05 
UTC ---
They're not really relevant to this bug. Maybe they are listed on some other
bug report already.

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-02-11 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

Phillip Patriakeas  changed:

   What|Removed |Added

 CC||dragonlordofxant...@gmail.c
   ||om

--- Comment #27 from Phillip Patriakeas  
2010-02-11 16:54:00 UTC ---
Are you going to provide a list of the unrecoverable revisions?

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-02-10 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

--- Comment #26 from Tim Starling  2010-02-11 02:56:12 
UTC ---
All the test cases on the English Wikipedia should be fixed now:

* 1.3 million revisions were broken by this bug and are now fixed
* 177 revisions were unrecoverable due to being damaged by a previous
compression script some years ago, while cluster4 and cluster5 were current.
* 333 revisions were unrecoverable due to the text row being missing, probably
due to a bug in the original 2005 compression script. 

The fix script still needs to be run on the other wikis, so this bug has to
stay open for now.

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-02-08 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

--- Comment #25 from Tim Starling  2010-02-08 22:37:26 
UTC ---
Report different issues on a separate bug report please.

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-02-08 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

--- Comment #24 from Platonides  2010-02-08 22:35:54 UTC 
---
That doesn't explain the existance of wrong ConcatenatedGzipHistoryBlob objects
(the serialized mItems length doesn't match with the real one).
Perhaps they were indeed different issues :S

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-02-08 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

--- Comment #23 from Graham87  2010-02-08 08:26:45 UTC ---
Thanks Tim for looking into this. I've added some text about this bug to:
http://en.wikipedia.org/wiki/MediaWiki:Missing-article



It'd be confusing to have this error message pop up when someone is checking
the history of a page. Since I had to read through your explanation twice to
understand, I hope that "database glitch" is OK for now as a layman's
explanation.

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[Bug 20757] Corruption of text from early 2005 due to HistoryBlobStub pointers broken by recompressTracked.php

2010-02-07 Thread bugzilla-daemon
https://bugzilla.wikimedia.org/show_bug.cgi?id=20757

Tim Starling  changed:

   What|Removed |Added

Summary|some text of old revisions  |Corruption of text from
   |in early 2005 is blank in   |early 2005 due to
   |the English Wikipedia   |HistoryBlobStub pointers
   ||broken by
   ||recompressTracked.php

--- Comment #22 from Tim Starling  2010-02-08 07:35:53 
UTC ---
OK I've checked a lot of these test cases, and they all seem to be the same, so
I'm changing the summary. All of the relevant revisions should now be serving
errors instead of pretending to be blank.

The original version of compressOld.php concatenated several revisions into one
"blob" and stored it in a random row in the old table. Then the other old rows
which needed data from the concatenated blob would get a pointer object, called
a HistoryBlobStub. This pointer object gave an old_id and content hash which
located the text for that revision.

After we started using external storage (ES), all the bulk data was moved out
of the core database. Now, to load a HistoryBlobStub, MW would first load the
old_id where the concatenated text used to be, where it would find a second
pointer (with old_flags=external), then it would follow the second pointer to
load the blob from ES. This was an inefficient situation, so I introduced a new
pointer type (the "two-part CGZ URL") which pointed directly from the rows
where the stub objects used to be, into ES. 

I then wrote a script called resolveStubs.php, and ran it, removing all
HistoryBlobStub objects from the database. Or at least, that's what I thought I
did. It transpires that these missing revisions above are all HistoryBlobStub
objects that somehow escaped resolveStubs.php. 

The current generation of recompression script, trackBlobs/recompressTracked,
has no appropriate handling for HistoryBlobStub. It leaves the HistoryBlobStub
objects in place, but removes the CGZ objects they point to, creating a broken
pointer. 

Due to a bug in Revision.php, the broken pointer was displayed as a blank page
instead of an error message. This is fixed in r62119.

Luckily I was fairly paranoid when I wrote trackBlobs/recompressTracked, and
all the data required for recovery appears to have been retained. It's just a
matter of writing a bug fix script.

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