Quorum write + sync replication: guarantees


(shikhar) #1

I have been digging into the consistency guarantees provided by
ElasticSearch and I am a bit confused by looking at the code. It seems like
the only time we look at how many replicas the write succeeded on is prior
to issuing the write
https://github.com/elasticsearch/elasticsearch/blob/20278f491ac3e62be30544a862344a9b8b1f647c/src/main/java/org/elasticsearch/action/support/replication/TransportShardReplicationOperationAction.java#L398-L418
[1].

So I want to ask a question which should hopefully have a clear answer.

  • write consistency level is quorum
  • replication type is sync
  • a write is issued. it succeeds on primary but not on a quorum of all the
    shards (primary shard & replicas). will this result in a failure response?

If yes, I would love to see some corroboration!

Cheers,

Shikhar

[1] related issue: definition of quorum in ES code is off. github issue
https://github.com/elasticsearch/elasticsearch/issues/6482.

--
You received this message because you are subscribed to the Google Groups "elasticsearch" group.
To unsubscribe from this group and stop receiving emails from it, send an email to elasticsearch+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/elasticsearch/CAHWG4DP-mMc-UoQ-RYMB1iA9770v-3QE3FxzTdEUoFxKz_N-sQ%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.


(shikhar) #2

On Thu, Jun 12, 2014 at 6:09 PM, shikhar shikhar@schmizz.net wrote:

It seems like the only time we look at how many replicas the write
succeeded on is prior to issuing the write
https://github.com/elasticsearch/elasticsearch/blob/20278f491ac3e62be30544a862344a9b8b1f647c/src/main/java/org/elasticsearch/action/support/replication/TransportShardReplicationOperationAction.java#L398-L418
[1].

I meant "how many replicas the write could succeed on"... of course how
many it actually succeded on can only happen after the fact :slight_smile:

--
You received this message because you are subscribed to the Google Groups "elasticsearch" group.
To unsubscribe from this group and stop receiving emails from it, send an email to elasticsearch+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/elasticsearch/CAHWG4DMkhJ59ALK4ZRS%2BQkDYpwhNPZ%3D_AXTNgf6prGnyHLGwDQ%40mail.gmail.com.
For more options, visit https://groups.google.com/d/optout.


(system) #3