Question

我试图从ruby调用mongodb cloneCollection命令。基于https://github.com/mongodb/mongo-ruby-driver/wiki/FAQ的第一个问题，我制作了这个测试脚本：

require "mongo"
include Mongo

db = MongoClient.new("localhost", 27017).db("test")

coll = "users2"
cmd = {}
cmd['cloneCollection'] = coll
cmd['from'] = "test.example.com:27017"
db.command(cmd)

但是，它不是克隆users2集合，而是创建一个具有相同名称的空数据库。无法弄清楚我做错了什么。有任何想法吗？谢谢！

Answer 1

以下Ruby程序是一个独立的工作示例，可以回答您的问题，完成源和目标mongod服务器的启动。

似乎cloneCollection的arg必须是完全限定的名称，例如“test”用于“test”数据库中的“users”集合。

require "mongo"

# startup source and destination mongod servers
source = { 'port' => 27018, 'dbpath' => 'data27018' }
dest = { 'port' => 27019, 'dbpath' => 'data27019' }
[ source, dest ].each do |server|
  dbpath = server['dbpath']
  system("rm -fr #{dbpath} && mkdir #{dbpath} && mongod --port #{server['port']} --dbpath #{dbpath} &")
end

sleep 10 # delay for mongod startup

db_name = 'test'
coll_name = 'users'
db_coll_name = "#{db_name}.#{coll_name}"

# create source collection
db = Mongo::MongoClient.new("localhost", source['port']).db(db_name)
coll = db[coll_name]
coll.insert({'name' => 'Gary'})

# cloneCollection from source to dest
db = Mongo::MongoClient.new("localhost", dest['port']).db(db_name)
cmd = BSON::OrderedHash.new
cmd['cloneCollection'] = db_coll_name
cmd['from'] = "localhost:#{source['port']}"
db.command(cmd)
# verify cloneCollection
p db[coll_name].find.to_a

# kill mongod servers
pids = `pgrep mongod`.split(/\n/).sort.slice(-2,2)
system("kill #{pids.join(' ')}")

如果您有任何其他问题，请与我们联系。

Answer 2

感到惊讶的是Mongo::DB没有cloneCollection方法，并且阅读上面的@Gary Murakami的优秀答案，我写了这片猴子补丁，但我对它有用其它：

class Mongo::DB
  def cloneCollection(remote_host, collection_name)
    cmd = BSON::OrderedHash.new
    cmd['cloneCollection'] = name + "." + collection_name
    cmd['from'] = remote_host
    self.command(cmd)
  end
end

只需将其放在源文件中的任意位置即可获得Mongo::DB.cloneCollection实施。

从ruby调用mongodb cloneCollection的正确方法

2 个答案: