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  1. Lucene - Core
  2. LUCENE-5438

add near-real-time replication



    • Improvement
    • Status: Resolved
    • Major
    • Resolution: Fixed
    • None
    • 6.0
    • modules/replicator
    • None
    • New


      Lucene's replication module makes it easy to incrementally sync index
      changes from a master index to any number of replicas, and it
      handles/abstracts all the underlying complexity of holding a
      time-expiring snapshot, finding which files need copying, syncing more
      than one index (e.g., taxo + index), etc.

      But today you must first commit on the master, and then again the
      replica's copied files are fsync'd, because the code operates on
      commit points. But this isn't "technically" necessary, and it mixes
      up durability and fast turnaround time.

      Long ago we added near-real-time readers to Lucene, for the same
      reason: you shouldn't have to commit just to see the new index

      I think we should do the same for replication: allow the new segments
      to be copied out to replica(s), and new NRT readers to be opened, to
      fully decouple committing from visibility. This way apps can then
      separately choose when to replicate (for freshness), and when to
      commit (for durability).

      I think for some apps this could be a compelling alternative to the
      "re-index all documents on each shard" approach that Solr Cloud /
      ElasticSearch implement today, and it may also mean that the
      transaction log can remain external to / above the cluster.


        1. LUCENE-5438.patch
          29 kB
          Michael McCandless
        2. LUCENE-5438.patch
          46 kB
          Michael McCandless
        3. LUCENE-5438.patch
          173 kB
          Michael McCandless
        4. LUCENE-5438.patch
          344 kB
          Michael McCandless



            mikemccand Michael McCandless
            mikemccand Michael McCandless
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