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From "Jens Alfke (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (COUCHDB-1670) Replicator crashes if numbers in checkpoint docs are expressed in scientific notation
Date Wed, 06 Feb 2013 18:39:14 GMT

    [ https://issues.apache.org/jira/browse/COUCHDB-1670?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13572655#comment-13572655
] 

Jens Alfke commented on COUCHDB-1670:
-------------------------------------

> since is opaque. You have to pass back exactly what you got from couchdb.

I don't think that's a reasonable expectation. The JSON is going to be transformed anyway
(to insert the _rev), so at some point it's going to be translated into an internal format
and then regenerated. The output has to be an equivalent JSON document, but that doesn't mean
byte-for-byte equivalence. For instance, object keys could be in a different order, Unicode
escapes could be turned into literals or vice versa, and numbers might be represented differently,
like changing to/from scientific notation or suppressing trailing zeros after the decimal
point.
                
> Replicator crashes if numbers in checkpoint docs are expressed in scientific notation
> -------------------------------------------------------------------------------------
>
>                 Key: COUCHDB-1670
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-1670
>             Project: CouchDB
>          Issue Type: Bug
>          Components: Replication
>            Reporter: Jens Alfke
>
> The CouchDB 1.2 replicator process crashes with an Erlang exception when parsing a checkpoint
document read back from a remote database, if numbers in the document were JSON-encoded in
scientific notation instead of as integers. This includes the properties source_last_seq,
end_last_seq, start_last_seq.
> That is, the following encoding works fine:
>     ..., "source_last_seq": 1234567, ...
> whereas this completely-equivalent encoding causes an exception:
>     ..., "source_last_seq": 1.234567e+06, ...
> This issue raised its head as a result of a CouchDB-compatible engine I'm writing (the
Couchbase Sync Gateway) which can serve as a passive replication endpoint. It's implemented
in Go, and the Go JSON package has the side effect of (a) parsing all JSON numbers into type
'double', and (b) encoding all doubles into JSON using scientific notation if they're more
than six digits long. The net effect is that when CouchDB stores a checkpoint into the Sync
Adapter's database and then later reads it back, it barfs due to the scientific notation.

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