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listDatabases The listDatabases command provides a list of all existing databases along with basic statistics about them. listDatabases命令提供所有现有数据库的列表以及有关它们的基本统计信息。The listDatabases must run against the admin database, as in the following example:listDatabases必须针对管理数据库运行，如下例所示：
db.adminCommand( { listDatabases: 1 } )
The value (e.g. 值（例如1) does not affect the output of the command.1）不会影响命令的输出。
The listDatabases command can take the following optional fields:listDatabases命令可以包含以下可选字段：
filter | document |
|
nameOnly | boolean |
|
authorizedDatabases | boolean |
|
comment | any |
|
When authentication is enabled:启用身份验证时：
For 对于连接到早期版本MongoDB部署（例如3.6.10）的mongosh connected to earlier versions of MongoDB deployment (e.g. 3.6.10),mongosh，
listDatabases action on the cluster resource, show dbs returns all databases.listDatabases操作，show dbs将返回所有数据库。listDatabases action on the cluster resource, show dbs returns only the databases for which the user has privileges (including those databases for which the user has privileges on specific collections).listDatabases操作，show dbs只返回用户有权限的数据库（包括用户对特定集合有权限的那些数据库）。For MongoDB 4.0.6+, the 对于MongoDB 4.0.6+，listDatabases命令根据分配给执行该命令的用户的权限和authorizedDatabases命令选项返回不同的值：listDatabases command returns different values based on the privileges assigned to the user who executes the command and the authorizedDatabases command option:
If authorizedDatabases is unspecified, and
If the user has listDatabases action on the cluster resource, listDatabases command returns all databases.
If the user does not have listDatabases action on the cluster, listDatabases command returns only the databases for which the user has privileges (including databases for which the user has privileges on specific collections).
If authorizedDatabases is true, listDatabases command returns only the databases for which the user has privileges (including databases for which the user has privileges on specific collections).
If authorizedDatabases is false, and
If the user has listDatabases action on the cluster, listDatabases command returns all databases
If the user does not have listDatabases action on the cluster, listDatabases command errors with insufficient permissions.
For MongoDB 4.0.5, the 对于MongoDB 4.0.5，listDatabases command returns different values based on the privileges assigned to the user who executes the command and the authorizedDatabases command option:listDatabases命令根据分配给执行该命令的用户的权限和authorizedDatabases命令选项返回不同的值：
If 如果未指定authorizedDatabases is unspecified, andauthorizedDatabases，并且
If the user has listDatabases action on the cluster resource, listDatabases command returns all databases.
If the user does not have listDatabases action on the cluster, listDatabases command returns only the databases for which the user has the find action on the database resource (and not the collection resource).
If authorizedDatabases is true, listDatabases command returns only the databases for which the user has the find action on the database resource (and not the collection resource).
If authorizedDatabases is false, and
If the user has listDatabases action on the cluster, listDatabases command returns all databases
If the user does not have listDatabases action on the cluster, listDatabases command errors with insufficient permissions.
For MongoDB 4.0.0-4.0.4, the listDatabases command returns different values based on the privileges assigned to the user who executes the command.
If the user has the listDatabases privilege action on the cluster, the listDatabases command returns a list of all existing databases.
If the user does not have the listDatabases privilege action on the cluster, the listDatabases command only returns a list of databases for which the user has the find action.
Starting in MongoDB 4.2, if the client that issued the 从MongoDB 4.2开始，如果在操作完成之前发出listDatabases disconnects before the operation completes, MongoDB marks the listDatabases for termination (i.e. killOp on the operation).listDatabases的客户端断开连接，MongoDB会标记listDatabases终止（即操作上的killOp）。
Starting in MongoDB 4.4, to run on a replica set member, 从MongoDB 4.4开始，要在副本集成员上运行，listDatabases operations require the member to be in PRIMARY or SECONDARY state. listDatabases操作要求成员处于PRIMARY或SECONDARY状态。If the member is in another state, such as 如果成员处于其他状态，如STARTUP2, the operation errors.STARTUP2，则操作将出错。
In previous versions, the operations can also be run when the member is in 在以前的版本中，当成员处于STARTUP2. STARTUP2时，也可以运行这些操作。However, the operations wait until the member transitions to 但是，这些操作会等到成员转换到RECOVERING.RECOVERING。
Run 对listDatabases against the admin database:admin数据库运行listDatabases：
db.adminCommand( { listDatabases: 1 } )
The following is an example of a 以下是listDatabases result:listDatabases结果的示例：
{
"databases" : [
{
"name" : "admin",
"sizeOnDisk" : 83886080,
"empty" : false
},
{
"name" : "local",
"sizeOnDisk" : 83886080,
"empty" : false
},
{
"name" : "test",
"sizeOnDisk" : 83886080,
"empty" : false
}
],
"totalSize" : 251658240,
"totalSizeMb" : 251,
"ok" : 1
}
Run 对listDatabases against the admin database. Specify the nameOnly: true option:admin数据库运行listDatabases。指定nameOnly:true选项：
db.adminCommand( { listDatabases: 1, nameOnly: true} )
The following is an example of a 以下是使用listDatabases results when run with the nameOnly: true option:nameOnly:true选项运行时的listDatabases结果示例：
{
"databases" : [
{
"name" : "admin"
},
{
"name" : "local"
},
{
"name" : "test"
}
],
"ok" : 1
}
Run 对listDatabases against the admin database. admin数据库运行listDatabases。Specify the 指定filter option to only list databases that match the specified filter criteria.filter选项以仅列出符合指定筛选条件的数据库。
For example, the following specifies a filter such that 例如，下面指定了一个筛选器，以便listDatabases only returns information on databases whose name matches the specified regular expression:listDatabases仅返回名称与指定regular expression匹配的数据库的信息：
db.adminCommand( { listDatabases: 1, filter: { "name": /^rep/ } } )
When executed against a 对mongos instance, listDatabases:mongos实例执行时，listDatabases：
shards embedded document to each database's summary document if nameOnly: false, andnameOnly:false，则向每个数据库的摘要文档添加一个嵌入shards的文档，并且local database.local数据库。Each element in the shards embedded document consists of a field whose key gives the name of a collection on that shard, and whose value represents the collection's size in bytes.shards嵌入文档中的每个元素都由一个字段组成，该字段的键给出该分片上集合的名称，其值表示集合的大小（以字节为单位）。
The sizeOnDisk field represents the total size of all listed collections and indexes.sizeOnDisk字段表示所有列出的集合和索引的总大小。
For example:例如：
{
"databases" : [
{
"name" : "admin",
"sizeOnDisk" : 16384,
"empty" : false,
"shards" : {
"config" : 16384
}
},
{
"name" : "config",
"sizeOnDisk" : 176128,
"empty" : false,
"shards" : {
"clients" : 28672,
"patients" : 8192,
"config" : 139264
}
},
{
"name" : "test",
"sizeOnDisk" : 12288,
"empty" : false,
"shards" : {
"clients" : 12288
}
}
],
"totalSize" : 204800,
"totalSizeMb" : 0,
"ok" : 1
}
listDatabases.databases Type: Array
Array of documents, each containing information on a single database.文档数组，每个文档包含单个数据库的信息。
listDatabases.databases.sizeOnDisk Type: Integer
Total size of the database files on disk, expressed in bytes.磁盘上数据库文件的总大小，以字节表示。
listDatabases.databases.shards Type: Document
Each element in the shards document consists of a field whose key gives the name of a collection on that shard, and whose value represents the collection's size in bytes.shards文档中的每个元素都包含一个字段，该字段的键给出了该shard上的集合的名称，其值表示集合的大小（以字节为单位）。
shards only appears in the output if nameOnly: false.nameOnly:false时，shards才会出现在输出中。
See Sharded Clusters for details.有关详细信息，请参阅分片集群。
listDatabases.totalSize Type: Integer
Sum of all the 所有sizeOnDisk fields in bytes.sizeOnDisk字段的总和（以字节为单位）。