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  1. Core Server
  2. SERVER-11683

Figure out mongod split triggering mechanism

    • Type: Icon: Task Task
    • Resolution: Duplicate
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: None
    • Component/s: Sharding
    • None

      Plan for 2.6:
      Wire existing logic to the write commands in mongos while preserving previous behaviour as much as possible.

      Plan for beyond 2.6:
      Move auto split mechanism to the shards. A separate entity will be tasked to keep track of the document sizes being inserted. This entity will have no knowledge of the entire chunk ranges and config for a collection and will only know ranges being fed to it. Basically, the api would look something like:

      class AutoSplitTracker {
      public:
        bool newDoc(const BSONObj& minChunkKey, const BSONObj& maxChunkKey, const BSONObj& doc) {
          // Check inconsistency in mix/max pair with our own map and delete inconsistent entries.
          // Inconsistent entries are caused by the changes in chunk boundaries due to the chunks being merged or splitted.
      
          _map[minChunkKey].increment(doc.objsize());
      
          if (_map[minChunkKey].size() > splitThreshold) {
             // use splitVector to determine if we actually need to split
          }
        }
      }
      

            Assignee:
            randolph@mongodb.com Randolph Tan
            Reporter:
            greg_10gen Greg Studer
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              Created:
              Updated:
              Resolved: