$listClusterCatalog

List Information from All Collections列出所有集合的信息

The following example returns default information from all collections in the sample_mflix database:以下示例返回sample_mflix数据库中所有集合的默认信息：

use sample_mflix

db.aggregate([
  {
    $listClusterCatalog: {}
  }
])

When you run this example, it returns an array containing a document for each collection in the sample_mflix database. Each of these documents contains the default fields described in the preceding table:运行此示例时，它返回一个数组，其中包含sample_mflix数据库中每个集合的文档。这些文档中的每一个都包含上表中描述的默认字段：

[
  {
    ns: "sample_mflix.movies",
    db: "sample_mflix",
    type: "collection",
    idIndex: { v: 2, key: { _id: 1 }, name: '_id' },
    options: { ... },
    sharded: false,
    info: {
        readOnly: false,
        uuid: new UUID("6c46c8b9-4999-4213-bcef-9a36b0cff228")
    }
  },
  {
    ns: "sample_mflix.comments",
    db: "sample_mflix",
    type: "collection",
    options: { ... },
    sharded: true,
    info: {
        readOnly: true,
        uuid: new UUID("6c448eb9-4090-4213-bbaf-9a36bb7fc98e")
    }
    shardKey: { _id: 1}
  },
  ...
]

Balancing Configuration平衡配置

You can return the default fields and information about the balancing configuration for all collections in a database with sharded collections.您可以为具有分片集合的数据库中的所有集合返回默认字段和有关平衡配置的信息。

The following example returns balancing configurations for the sample_mflix database:以下示例返回sample_mflix数据库的平衡配置：

use sample_mflix

db.aggregate([
  {
    $listClusterCatalog: {
      balancingConfiguration: true
    }
  }
])

The preceding example returns an array containing a document for each collection. Each of these documents contains the default fields along with the balancingEnabled, balancingEnabledReason, autoMergingEnabled, and chunkSize fields for sharded collections. The following code provides an example of this output:前面的示例返回一个数组，其中包含每个集合的文档。这些文档中的每一个都包含默认字段以及分片集合的balancingEnabled、balancingEnabledReason、autoMergeEnabled和chunkSize字段。以下代码提供了此输出的示例：

[
  {
    ns: "sample_mflix.movies",
    db: "sample_mflix",
    type: "collection",
    idIndex: { v: 2, key: { _id: 1 }, name: '_id' },
    options: { ... },
    sharded: false,
    ...
  },
  {
    ns: "sample_mflix.comments",
    db: "sample_mflix",
    type: "collection",
    sharded: true,
    shardKey: { _id: 1},
    balancingEnabled: true,
    balancingEnabledReason: {
      enableBalancing: true,
      allowMigrations: false
    },
    autoMergingEnabled: false,
    chunkSize: 256,
    ...
  },
  ...
]

List Information from All Collections in a Database列出数据库中所有集合的信息

The following example creates a pipeline stage that returns information for all collections in the sample_mflix database. The example then runs the pipeline:以下示例创建了一个管道阶段，该阶段返回sample_mflix数据库中所有集合的信息。然后，该示例运行管道：

const pipeline = [{ $listClusterCatalog: {} }];

const db = client.db("sample_mflix");

const cursor = db.aggregate(pipeline);
return cursor;

List Information from All Collections in a Cluster列出群集中所有集合的信息

The following example creates a pipeline stage that returns information for all collections in a cluster. The example then runs the pipeline:以下示例创建了一个管道阶段，该阶段返回集群中所有集合的信息。然后，该示例运行管道：

const pipeline = [{ $listClusterCatalog: {} }];

const adminDB = client.db("admin");

const cursor = adminDB.aggregate(pipeline);
return cursor;

Balancing Configuration平衡配置

The following example creates a pipeline that includes balancing information in the return documents for all collections in the sample_mflix database. The example then runs the pipeline:以下示例创建了一个管道，该管道在sample_mflix数据库中所有集合的返回文档中包含平衡信息。然后，该示例运行管道：

const db = client.db("sample_mflix");

const pipeline = [{ $listClusterCatalog: {balancingConfiguration: true} }];

const cursor = db.aggregate(pipeline);
return cursor;