Uploaded image for project: 'Core Server'
  1. Core Server
  2. SERVER-8527

$external database is created as a database and prevented sharding

    • Type: Icon: Bug Bug
    • Resolution: Done
    • Priority: Icon: Major - P3 Major - P3
    • 2.4.0-rc1
    • Affects Version/s: 2.4.0-rc0
    • Component/s: Security, Sharding
    • None
    • Environment:
      MongoDB2.4.0-rc0
    • Fully Compatible
    • ALL
    • Hide

      See above

      Show
      See above

      The $external useSource was somehow created as a database, which doesn't seem to be quite logical. It should be an external artifact I'd have thought.

      I discovered this during testing of adding a sharded cluster infrastructure consisting of two already-Kerborised replica sets.

      1. Step : added realm4 replica set as a shard

      mongos> sh.addShard( "realm4/kserver1a.realm4.10gen.me:27017" )
      { "shardAdded" : "realm4", "ok" : 1 }
      

      2. Step : added realm5 set as a shard, however, this is rejected due to the existence of the $external database on both realms. This is logical but it means some reconfiguration if making two Kerberos-enabled replica sets part of a sharded cluster.

      mongos> sh.addShard( "realm5/kserver1a.realm5.10gen.me:27017" )
      {
      	"ok" : 0,
      	"errmsg" : "can't add shard realm5/kserver1a.realm5.10gen.me:27017 because a local database '$external' exists in another realm4:realm4/kserver1a.realm4.10gen.me:27017,kserver1b.realm4.10gen.me:27017,kserver1c.realm4.10gen.me:27017"
      }
      

      So as expected, I can drop the $external database below -

      realm5:PRIMARY> db.dropDatabase()
      { "dropped" : "$external", "ok" : 1 }
      realm5:PRIMARY> 
      realm5:PRIMARY> 
      realm5:PRIMARY> 
      realm5:PRIMARY> show dbs
      $SERVER	(empty)
      admin	0.0625GB
      db1	0.0625GB
      fred	(empty)
      local	1.07763671875GB
      

      After removing the $external database, I can now add realm5 as the second shard -

      mongos> sh.addShard( "realm5/kserver1a.realm5.10gen.me:27017" )
      { "shardAdded" : "realm5", "ok" : 1 }
      
      mongos> sh.status()
      --- Sharding Status --- 
        sharding version: {
      	"_id" : 1,
      	"version" : 3,
      	"minCompatibleVersion" : 3,
      	"currentVersion" : 4,
      	"clusterId" : ObjectId("511a58f8bc0ae36e0fab6574")
      }
        shards:
      	{  "_id" : "realm4",  "host" : "realm4/kserver1a.realm4.10gen.me:27017,kserver1b.realm4.10gen.me:27017,kserver1c.realm4.10gen.me:27017" }
      	{  "_id" : "realm5",  "host" : "realm5/kserver1a.realm5.10gen.me:27017,kserver1b.realm5.10gen.me:27017,kserver1c.realm5.10gen.me:27017" }
        databases:
      	{  "_id" : "admin",  "partitioned" : false,  "primary" : "config" }
      	{  "_id" : "fred",  "partitioned" : false,  "primary" : "realm4" }
      	{  "_id" : "$external",  "partitioned" : false,  "primary" : "realm4" }
      	{  "_id" : "db1",  "partitioned" : false,  "primary" : "realm5" }
      

      Out of curiousity what is the $SERVER database? I never created it.

            Assignee:
            schwerin@mongodb.com Andy Schwerin
            Reporter:
            mark Mark porter
            Votes:
            0 Vote for this issue
            Watchers:
            3 Start watching this issue

              Created:
              Updated:
              Resolved: