Mike Wallace created COUCHDB-2774:
-------------------------------------
Summary: COPY request create a target document with a different
revision hash
Key: COUCHDB-2774
URL: https://issues.apache.org/jira/browse/COUCHDB-2774
Project: CouchDB
Issue Type: Bug
Security Level: public (Regular issues)
Components: Database Core
Reporter: Mike Wallace
HTTP COPY requests create an identical copy of the source document. As the body
of the target is unchanged the revision hash should also be unchanged, however
that is not currently the case:
$ URL=http://localhost:15984
$ curl -X PUT $URL/doge
{"ok":true}
$ curl -X PUT $URL/doge/shibe1 -d '{"such doge":"very doc"}'
{"ok":true,"id":"shibe1","rev":"1-6429670183877c94fed5cc7996cd880a"}
$ curl -X COPY $URL/doge/shibe1 -H 'Destination: shibe2'
{"ok":true,"ok":true,"id":"shibe2","rev":"1-c73d863c32ec87653923959eae56920b"}
$ curl -X GET $URL/doge/shibe2
{"_id":"shibe2","_rev":"1-c73d863c32ec87653923959eae56920b","such doge":"very
doc"}
The reason for the difference is because the document opened in the copy
handler has a binary body [1]. When the revision hash is generated on update
the binary is passed into couch_db:new_revid/1 and hence the hash is different.
If we change the binary body to an ejson body and save the doc then the
revision hash is the same [2].
There are two possible solutions. One is to add a clause to
couch_db:new_revid/1 which converts any binary doc bodies to ejson [3], the
alternative is to open the doc with the ejson_body option in the chttpd_db
handler fun.
I prefer the second approach, using ejson_body to open the doc in chttpd_db,
since it is simpler and further up the stack, so less likely to have any
unfortunate side-effects.
Unless anyone comments to the contrary I'll PR the second option.
[1] https://github.com/apache/couchdb-chttpd/blob/master/src/chttpd_db.erl#L774
[2] https://gist.github.com/mikewallace1979/592b65b2e51ca5f9a1a7
[3]
https://github.com/apache/couchdb-couch/commit/2b44b8d6eb865e24e05866e7aa8dd57d076a01d6
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