Mike Rhodes created COUCHDB-2947:
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Summary: Applying limit and continuous to _changes results in odd
behavior when writing documents during request
Key: COUCHDB-2947
URL: https://issues.apache.org/jira/browse/COUCHDB-2947
Project: CouchDB
Issue Type: Bug
Components: Database Core
Reporter: Mike Rhodes
If I have a database that is continuously receiving updates, applying
continuous and limit parameters to my database query gives odd behaviour.
Take this URL:
http://localhost:5984/database/_changes?since=0&limit=1&feed=continuous
If I call this URL while running a script writing documents to the database at
a great enough rate that the continuous changes timeout is not hit, the
behaviour isn't as I'd expect.
What I'd expect to happen:
1 doc is emitted, the _changes feed emits the last_seq line, then the request
is terminated.
What actually happens:
Once `limit` items have been returned, entries continue being emitted until
writing documents to the database stops. After writing stops, entries stop
being emitted into the response. If I start writing again, the response starts
to emit changes entries again. If I don't start writing again, the request
eventually times out via the default setting in couch.ini and emits the
last_seq line and closes.
If a timeout is applied in the URL, this overrides the default timeout as
expected, but otherwise the behaviour remains the same.
Note that the _changes feed isn't catching up to the current seq, it's just
continuing to emit while the documents are being written. Once writing to the
database stops, the request stops emitting changes wherever it's managed to get
up to. From what I can tell, the emitted entries into the changes feed are in
the right sequence, so we're not missing items from the feed, just emitting too
many of them.
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