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  1. Core Server
  2. SERVER-19075

printShardingStatus/sh.status should show overall chunk count summary

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    • Sharding EMEA

    Description

      Determining the overall balance of a cluster from the output of sh.status() requires scrolling through all the sharded collections. If there are a lot of sharded collections[1], this is a pain.

      Thus the output should include an overall summary of the chunk distribution among the shards.

      Either augment the existing "shards" output to include the number of chunks, e.g.:

       > sh.status()
       --- Sharding Status ---
         sharding version: {
               "_id" : 1,
               "minCompatibleVersion" : 6,
               "currentVersion" : 7,
               "clusterId" : ObjectId("556f97135efa42f9f4eaedd1")
       }
         shards:
      -        {  "_id" : "shard01",  "host" : "genique:11112" }
      -        {  "_id" : "shard02",  "host" : "genique:11113" }
      +        {  "_id" : "shard01",  "host" : "genique:11112", numChunks: 34 }
      +        {  "_id" : "shard02",  "host" : "genique:11113", numChunks: 22 }
         balancer:
               Currently enabled:  yes
               Currently running:  no
               Failed balancer rounds in last 5 attempts:  0
               Migration Results for the last 24 hours:
                       No recent migrations
         databases:
               ...
      

      Or else add a new top-level "chunks" section (mimicking the per-collection output), e.g.:

       > sh.status()
       --- Sharding Status ---
         sharding version: {
               "_id" : 1,
               "minCompatibleVersion" : 6,
               "currentVersion" : 7,
               "clusterId" : ObjectId("556f97135efa42f9f4eaedd1")
       }
         shards:
               {  "_id" : "shard01",  "host" : "genique:11112" }
               {  "_id" : "shard02",  "host" : "genique:11113" }
         balancer:
               Currently enabled:  yes
               Currently running:  no
               Failed balancer rounds in last 5 attempts:  0
               Migration Results for the last 24 hours:
                       No recent migrations
      +  chunks:
      +        shard01    34
      +        shard02    22
         databases:
               ...
      

      [1]: Or worse, a lot of sharded collections with just under 20 chunks (or verbose=true was used) and/or shard keys that exceed 1 line in tojson().

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            backlog-server-sharding-emea [DO NOT USE] Backlog - Sharding EMEA
            kevin.pulo@mongodb.com Kevin Pulo
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              Updated:
              Resolved: