[
https://issues.apache.org/jira/browse/COUCHDB-3314?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15928433#comment-15928433
]
Joan Touzet commented on COUCHDB-3314:
--------------------------------------
Further to the IRC discussion with [~janl], [~rnewson] and [~paul.joseph.davis]
I raised the concern that this could frustrate users who independently
calculate document checksums and are unable to predict the {{_rev}} value.
However, the ability to *specify your own {{\_rev}} value* should avoid this
problem. It should also allow the 'same doc creation at two disconnected sites
get the same {{\_rev}}' scenario to work, assuming the client code at both
sites _also_ includes the precalculated {{\_rev}}.
Or, as [~rnewson] put it:
{quote}
10:53 <+rnewson> so, the semantic is this. on doc creation (brand new id or old
id to deleted doc) gets a random _rev _unless_ a rev is specified (if it is, we
use it, and I think bump it)
{quote}
If the above is true I'm +1, with the usual caveats of "document this very
clearly."
> Add an option in doc creation APIs to specify a random value for an initial
> doc revision
> ----------------------------------------------------------------------------------------
>
> Key: COUCHDB-3314
> URL: https://issues.apache.org/jira/browse/COUCHDB-3314
> Project: CouchDB
> Issue Type: New Feature
> Components: Database Core, HTTP Interface
> Reporter: Mayya Sharipova
>
> Currently the initial revision of a document is deterministic. For instance,
> anyone that has created an empty document probably recognizes the revision
> starting with "1-967a00dff...". In order to account for situations when a
> document is continually purged and recreated we're going to add randomness to
> this initial revision by specifying a 0-$rev in the request coordinator. We
> will then include this in the revision generation but drop the 0-$rev entry
> from the revision's path.
> Thus, the new API will look like this:
> acurl -X PUT
> https://http://adm:[email protected]:5984/test-db/newdoc1?rev=0-adfdafa123 -d
> '{}'
> And similarly for _bulk_docs
> For a user who wants to create a doc, then purge it, and then re-create, it
> is recommended to recreate it with another random revision.
> It is important to note that the 0-$rev only affects document creation. Once
> a document exists, updates to the document will continue to update their hash
> in the same deterministic fashion. Ie, once a document exists, identical
> updates will result in identical revisions.
> _________________
> The following changes need to be made in the code:
> 1. API changes to allow to specify random rev in doc PUT requests, _bulk_docs
> 2. Internals:
> 2.1 Use a new revision here:
> https://github.com/apache/couchdb-couch/blob/master/src/couch_db.erl#L886
> 2.2 Don't include provided 0-$rev entry to the revision's path (find wherever
> new_revid is called from; could be 2-3 places)
> 2.3 Reject a 0-$rev during replication
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
