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POSharding do not balance data to two shards
 

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  1. POSharding do not balance data to two shards
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    <p>I have added two shards as follows:</p> <pre><code> shards: { "_id" : "rs0", "host" : "rs0/serv1:27017,serv2:27017,serv3:27017" } { "_id" : "rs1", "host" : "rs1/serv3:27017,serv4:27017,serv5:27017" } </code></pre> <p>I have sharded my collection posts as follows:</p> <p>databases:</p> <pre><code>{ "_id" : "mypost", "partitioned" : true, "primary" : "rs0" } mypost.posts shard key: { "_id" : "hashed" } chunks: rs0 2 { "_id" : { "$minKey" : 1 } } --&gt;&gt; { "_id" : NumberLong(0) } on : rs0 Timestamp(1, 0) { "_id" : NumberLong(0) } --&gt;&gt; { "_id" : { "$maxKey" : 1 } } on : rs0 Timestamp(1, 1) </code></pre> <p>My question is even though I use hashed key on _id and inserted 34MB of data why data is always fetched from shard 1 only and no chunk is moved to shard 2.</p> <p>when I do</p> <pre><code>db.posts.find().explain() i get: { "clusteredType" : "ParallelSort", "shards" : { "rs0/serv1:27017,serv2:27017,serv3:27017" : [ { "cursor" : "BasicCursor", "isMultiKey" : false, "n" : 1000, "nscannedObjects" : 1000, "nscanned" : 1000, "nscannedObjectsAllPlans" : 1000, "nscannedAllPlans" : 1000, "scanAndOrder" : false, "indexOnly" : false, "nYields" : 0, "nChunkSkips" : 0, "millis" : 4, "indexBounds" : { }, "server" : "serv1:27017" } ] }, "cursor" : "BasicCursor", "n" : 1000, "nChunkSkips" : 0, "nYields" : 0, "nscanned" : 1000, "nscannedAllPlans" : 1000, "nscannedObjects" : 1000, "nscannedObjectsAllPlans" : 1000, "millisShardTotal" : 4, "millisShardAvg" : 4, "numQueries" : 1, "numShards" : 1, "indexBounds" : { }, "millis" : 5 } </code></pre> <p>How can my data be sent to both the shard automatically.</p> <p>sh.status()</p> <pre><code> sharding version: { "_id" : 1, "version" : 3, "minCompatibleVersion" : 3, "currentVersion" : 4, "clusterId" : ObjectId("50fde9a8552b8ce5c47c8ead") } shards: { "_id" : "rs0", "host" : "rs0/serv1:27017,serv2:27017,serv3:27017" } { "_id" : "rs1", "host" : "rs1/serv4:27017,serv5:27017,serv6:27017" } databases: { "_id" : "admin", "partitioned" : false, "primary" : "config" } { "_id" : "myposts", "partitioned" : true, "primary" : "rs0" } myposts.posts shard key: { "_id" : "hashed" } chunks: rs0 1 { "_id" : { "$minKey" : 1 } } --&gt;&gt; { "_id" : { "$maxKey" : 1 } } on : rs0 Timestamp(1, 0) </code></pre> <p>status after delete of collection---------------------</p> <pre><code>{ "_id" : "myposts", "partitioned" : true, "primary" : "rs0" } myposts.posts shard key: { "_id" : "hashed" } chunks: rs0 2 { "_id" : { "$minKey" : 1 } } --&gt;&gt; { "_id" : NumberLong(0) } on : rs0 Timestamp(1, 0) { "_id" : NumberLong(0) } --&gt;&gt; { "_id" : { "$maxKey" : 1 } } on : rs0 Timestamp(1, 1) </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USPhalguni Mukherjee
    1. USPhalguni Mukherjee
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. COsh.status() output? You seem to have a shard key that only consists of the value `0` which is odd
      singulars
      1. POSharding do not balance data to two shards
      1. USSammaye
    2. CO@Sammaye can you explain a bit detail?
      singulars
      1. POSharding do not balance data to two shards
      1. USPhalguni Mukherjee
    3. CO@Sammaye my id field values are all diffrenet:{ "_id" : ObjectId("50ab0f8bbcf1bfe2536dc3f8") } { "_id" : ObjectId("50ab0f8bbcf1bfe2536dc3f9") } { "_id" : ObjectId("50ab0f8bbcf1bfe2536dc3fa") } { "_id" : ObjectId("50ab0f8bbcf1bfe2536dc3fb") }
      singulars
      1. POSharding do not balance data to two shards
      1. USPhalguni Mukherjee
 

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