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From "Szabo, Viktor" <Viktor.Sz...@morganstanley.com>
Subject RE: possible compact bug in 1.1.1
Date Mon, 20 Feb 2012 22:42:16 GMT
Yes, the re-insertion took place after the compaction completed.

Should it matter? Does it matter?

Thanks,
Viktor

-----Original Message-----
From: CGS [mailto:cgsmcmlxxv@gmail.com] 
Sent: 20 February 2012 23:22
To: user@couchdb.apache.org
Subject: Re: possible compact bug in 1.1.1

Hi,

Was the compaction finished when you tried to insert the document?

CGS




On Mon, Feb 20, 2012 at 10:16 PM, Szabo, Viktor < Viktor.Szabo@morganstanley.com> wrote:

> Hi,
>
> An application we have is using bulk writes to insert objects into the 
> database, and occasionally some documents get lost. It turns out this 
> happens for the very same reason described below. If we're re-insering 
> a doc using an id that has been deleted earlier, if the contents match 
> the payload that was saved when the id got used for the first time, 
> the doc remains in "deleted" state and the client gets a misleading 
> response. This only happens when the database is compacted after the 
> delete operation is executed.
>
> I still feel that this is pretty nasty - what do you guys think?
>
> Looking at the reply coming from _bulk_docs, there's no way I can tell 
> if I can read back my doc from the database or not.
>
> Below are the steps to reproduce.
>
> Thanks,
> Viktor
>
> $ curl -X POST -H "Content-type: application/json"
> http://server/database/_bulk_docs -d '{"docs" : [ { "_id" : "bug", "key"
> : "value" } ] }'
> [{"id":"bug","rev":"1-59414e77c768bc202142ac82c2f129de"}]
>
> $ curl -X GET http://server/database/bug 
> {"_id":"bug","_rev":"1-59414e77c768bc202142ac82c2f129de","key":"value"
> }
>
> $ curl -X DELETE
> http://server/database/bug?rev=1-59414e77c768bc202142ac82c2f129de
> {"ok":true,"id":"bug","rev":"2-9b2e3bcc3752a3a952a3570b2ed4d27e"}
>
> $ curl -X GET http://server/database/bug 
> {"error":"not_found","reason":"deleted"}
>
> $ curl -X POST -H "Content-type: application/json"
> http://server/database/_bulk_docs -d '{"docs" : [ { "_id" : "bug", "key"
> : "value" } ] }'
> [{"id":"bug","rev":"3-82b9390af5b7c003e03c0dd7e6aac45a"}]
>
> $ curl -X GET http://server/database/bug 
> {"_id":"bug","_rev":"3-82b9390af5b7c003e03c0dd7e6aac45a","key":"value"
> }
>
> $ curl -X DELETE
> http://server/database/bug?rev=3-82b9390af5b7c003e03c0dd7e6aac45a
> {"ok":true,"id":"bug","rev":"4-1f98d35af7fd5ce66197980f295e5dba"}
>
> $  curl -X POST -H "Content-type: application/json"
> http://server/database/_compact
> {"ok":true}
>
> $ curl -X GET http://server/database/bug 
> {"error":"not_found","reason":"deleted"}
>
> $ curl -X POST -H "Content-type: application/json"
> http://server/database/_bulk_docs -d '{"docs" : [ { "_id" : "bug", "key"
> : "value" } ] }'
> [{"id":"bug","rev":"1-59414e77c768bc202142ac82c2f129de"}]
>
> $ curl -X GET http://server/database/bug 
> {"error":"not_found","reason":"deleted"}
>
>
> -----Original Message-----
> From: Marcello Nuccio [mailto:marcello.nuccio@gmail.com]
> Sent: 23 November 2011 14:38
> To: user@couchdb.apache.org
> Subject: Re: possible compact bug in 1.1.1
>
> When a new document is created, the response is 201, not 200.
> If the posted document is identical to the one saved, the revision is 
> the same (otherwise it would have been a conflict). So the revision 
> you have is not obsolete.
>
> Marcello
>
> 2011/11/23 Szabo, Viktor (Enterprise Infrastructure)
> <Viktor.Szabo@morganstanley.com>:
> > I'd rather know about the fact that I haven't just successfully 
> > created a doc, but re-submitted a revision that was already known - 
> > and is already obsolete as revisions with higher version numbers 
> > already
> exist.
> >
> > Cheers,
> > Viktor
> >
> > -----Original Message-----
> > From: Marcello Nuccio [mailto:marcello.nuccio@gmail.com]
> > Sent: 23 November 2011 13:41
> > To: user@couchdb.apache.org
> > Subject: Re: possible compact bug in 1.1.1
> >
> > Can you elaborate on why you want a conflict?
> > I find it confusing to have a conflict when, in fact, there can't be 
> > any
> conflict since nothing has changed.
> >
> > Marcello
> >
> > 2011/11/23 Szabo, Viktor (Enterprise Infrastructure)
> > <Viktor.Szabo@morganstanley.com>:
> >> Thanks Paul, this makes sense.
> >>
> >> If it counts, I vote for forcing a conflict ;)
> >>
> >> Cheers,
> >> Viktor
> >>
> >> -----Original Message-----
> >> From: Paul Davis [mailto:paul.joseph.davis@gmail.com]
> >> Sent: 22 November 2011 20:54
> >> To: user@couchdb.apache.org
> >> Subject: Re: possible compact bug in 1.1.1
> >>
> >>
> >> Your example here is actually hitting a very specific edge case as
> demonstrated by Marcello's test. As of many versions ago, revisions 
> are generated using a hashing scheme of the document contents. In your 
> particular case the requests you're issuing contain the same identical 
> data in such a way that CouchDB will generate a revision of the doc.
> >>
> >> Given this, we then have to look at how this plays into replication.
> >> Basically, when we merge the revision trees we get to the case 
> >> where
> it's "oh, we already have this version, cool" because we do already 
> have this version.
> >>
> >> Whether or not that behavior is best, or if we should force a 
> >> conflict
> if we don't add a leaf during a write is another question. In other 
> words, the system is working fine, but this particular behavior can be 
> a bit unexpected.
> >>
> >> -------------------------------------------------------------------
> >> --
> >> -
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> NOTICE: Morgan Stanley is not acting as a municipal advisor and the 
> opinions or views contained herein are not intended to be, and do not 
> constitute, advice within the meaning of Section 975 of the Dodd-Frank 
> Wall Street Reform and Consumer Protection Act. If you have received 
> this communication in error, please destroy all electronic and paper 
> copies and notify the sender immediately. Mistransmission is not 
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> reserves the right, to the extent permitted under applicable law, to 
> monitor electronic communications. This message is subject to terms 
> available at the following
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NOTICE: Morgan Stanley is not acting as a municipal advisor and the opinions or views contained
herein are not intended to be, and do not constitute, advice within the meaning of Section
975 of the Dodd-Frank Wall Street Reform and Consumer Protection Act. If you have received
this communication in error, please destroy all electronic and paper copies and notify the
sender immediately. Mistransmission is not intended to waive confidentiality or privilege.
Morgan Stanley reserves the right, to the extent permitted under applicable law, to monitor
electronic communications. This message is subject to terms available at the following link:
http://www.morganstanley.com/disclaimers. If you cannot access these links, please notify
us by reply message and we will send the contents to you. By messaging with Morgan Stanley
you consent to the foregoing.

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