mongodb - MongoDB 删除 mapreduce 集合

Question

由于客户端代码中的错误，mongodb 创建了许多“mr.mapreduce ....”集合，如何将它们全部删除（可能通过掩码）。

Answer 1

我在交互式 shell 中运行脚本：

function f() {
    var names = db.getCollectionNames();
    for(var i = 0; i < names.length; i++){
    if(names[i].indexOf("mr.") == 0){
    db[names[i]].drop();}}};
f();

它解决了我的问题。

Answer 2

Temporary map-reduce table should be cleaned up when the connection which created them is closed:

map/reduce is invoked via a database command. The database creates a temporary collection to hold output of the operation. The collection is cleaned up when the client connection closes, or when explicitly dropped. Alternatively, one can specify a permanent output collection name. map and reduce functions are written in JavaScript and execute on the server.

-- MongoDB docs

If not, you could delete them using them same method you would delete any other collection. It might get a bit repetitive though.

Answer 3

实现相同目的的另一种方法是这个片段：

db.system.namespaces.find({name: /tmp.mr/}).forEach(function(z) {
  try{
    db.getMongo().getCollection( z.name ).drop();
  } catch(err) {}
});

优点：它不会尝试将所有命名空间收集到 JavaScript 数组中。MongoDB 在太多命名空间上的段错误。

Answer 4

当创建它们的连接关闭时，应清理临时 map-reduce 集合。但是有时它们会保留在那里并增加数据库大小。您可以使用以下脚本删除它们：

var database = db.getSiblingDB('yourDatabaseName');
var tmpCollections = database.getCollectionInfos(
    {
        name: {$regex: /tmp\.mr*/},
        'options.temp': true,
    });

tmpCollections.forEach(function (collection) {
    database.getCollection(collection.name).drop();
});

print(`There was ${tmpCollections.length} tmp collection deleted`);

该drop.tmp.js脚本可以从命令行执行，如下所示：

mongo --quiet mongodb://mongodb:27137 drop.tmp.js