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collStats The collStats command returns a variety of storage statistics for a given collection.collStats命令返回给定集合的各种存储统计信息。
To run 要运行collStats, use the db.runCommand( { <command> } ) method.collStats，请使用db.runCommand( { <command> } )方法。
The collStats command has the following syntax:collStats命令具有以下语法：
{
collStats: <string>,
scale: <int>
}
The command takes the following fields:该命令接受以下字段：
collStats | string | |
scale | int |
|
Unless otherwise specified by the metric name (such as 除非由度量名称（例如"bytes currently in the cache"), values related to size are displayed in bytes and can be overridden by scale."bytes currently in the cache"）另行指定，否则与大小相关的值以字节为单位显示，并且可以按scale覆盖。
The scale factor rounds the affected size values to whole numbers.比例因子将受影响的大小值舍入为整数。
After an unclean shutdown of a 在使用Wired Tiger存储引擎的mongod using the Wired Tiger storage engine, size statistics reported by collStats may be inaccurate.mongod不干净关闭后，collStats报告的大小统计数据可能不准确。
The amount of drift depends on the number of insert, update, or delete operations performed between the last checkpoint and the unclean shutdown. 漂移量取决于在最后一个检查点和不干净关闭之间执行的插入、更新或删除操作的数量。Checkpoints usually occur every 60 seconds. 检查点通常每60秒出现一次。However, 然而，使用非默认mongod instances running with non-default --syncdelay settings may have more or less frequent checkpoints.--syncdelay设置运行的mongod实例可能或多或少有检查点。
Run 在validate on each collection on the mongod to restore statistics after an unclean shutdown.mongod上的每个集合上运行validate，以在不干净的关闭后恢复统计数据。
After an unclean shutdown:不干净停机后：
Starting in MongoDB 4.2, the 从MongoDB 4.2开始，collStats includes information on indexes currently being built. collStats包含当前正在构建的索引的信息。For details, see:有关详细信息，请参阅：
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，collStats operations require the member to be in PRIMARY or SECONDARY state. collStats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，也可以在成员处于STARTUP2. STARTUP2时运行操作。However, the operations wait until the member transitions to 但是，操作将等待成员转换到RECOVERING.RECOVERING。
If you run 如果对不存在的集合运行collStats for a non-existent collection, then depending on your database implementation, collStats might return 0 values in the output fields instead of returning an error.collStats，则根据数据库实现，collStats可能会在输出字段中返回0值，而不是返回错误。
For Example:例如：
db.runCommand( { collStats : "nonExistentCollection" } )
Example output with 字段中值为0 values in the fields:0的输出示例：
{
ns: 'test.nonExistentCollection',
size: 0,
count: 0,
...
}
The following operation runs the 以下操作在collStats command on the restaurants collection, specifying a scale of 1024 bytes:restaurants集合上运行collStats命令，指定1024字节的比例：
db.runCommand( { collStats : "restaurants", scale: 1024 } )
The following document provides a representation of the 以下文档提供了collStats output. collStats输出的表示。Depending on the configuration of your collection and the storage engine, the output fields may vary.根据集合和存储引擎的配置，输出字段可能会有所不同。
{
"ns" : <string>,
"size" : <number>,
"timeseries" : {
"bucketsNs" : <bucketName>,
"bucketCount" : <number>,
"avgBucketSize" : <number>,
"numBucketInserts" : <number>,
"numBucketUpdates" : <number>,
"numBucketsOpenedDueToMetadata" : <number>,
"numBucketsClosedDueToCount" : <number>,
"numBucketsClosedDueToSize" : <number>,
"numBucketsClosedDueToTimeForward" : <number>,
"numBucketsClosedDueToTimeBackward" : <number>,
"numBucketsClosedDueToMemoryThreshold" : <number>,
"numCommits" : <number>,
"numWaits" : <number>,
"numMeasurementsCommitted" : <number>,
"avgNumMeasurementsPerCommit": <number>
},
"count" : <number>,
"avgObjSize" : <number>,
"storageSize" : <number>,
"freeStorageSize" : <number>,
"capped" : <boolean>,
"max" : <number>,
"maxSize" : <number>,
"wiredTiger" : {
"metadata" : {
"formatVersion" : <num>
},
"creationString" : <string>
"type" : <string>,
"uri" : <string>,
"LSM" : {
"bloom filter false positives" : <number>,
"bloom filter hits" : <number>,
"bloom filter misses" : <number>,
"bloom filter pages evicted from cache" : <number>,
"bloom filter pages read into cache" : <number>,
"bloom filters in the LSM tree" : <number>,
"total size of bloom filters" : <number>,
"chunks in the LSM tree" : <number>,
"highest merge generation in the LSM tree" : <number>,
"queries that could have benefited from a Bloom filter that did not exist" : <number>,
"sleep for LSM checkpoint throttle" : <number>,
"sleep for LSM merge throttle" : <number>
"total size of bloom filters" : <number>
},
"block-manager" : {
"allocations requiring file extension" : <number>,
"blocks allocated" : <number>,
"blocks freed" : <number>,
"checkpoint size" : <number>,
"file allocation unit size" : <number>,
"file bytes available for reuse" : <number>,
"file magic number" : <number>,
"file major version number" : <number>,
"file size in bytes" : <number>,
"minor version number" : <number>
},
"btree" : {
"btree checkpoint generation" : <number>,
"column-store fixed-size leaf pages" : <number>,
"column-store internal pages" : <number>,
"column-store variable-size RLE encoded values" : <number>,
"column-store variable-size deleted values" : <number>,
"column-store variable-size leaf pages" : <number>,
"fixed-record size" : <number>,
"maximum internal page key size" : <number>,
"maximum internal page size" : <number>,
"maximum leaf page key size" : <number>,
"maximum leaf page size" : <number>,
"maximum leaf page value size" : <number>,
"maximum tree depth" : <number>,
"number of key/value pairs" : <number>,
"overflow pages" : <number>,
"pages rewritten by compaction" : <number>,
"row-store empty values" : <number>,
"row-store internal pages" : <number>,
"row-store leaf pages" : <number>
},
"cache" : {
"bytes currently in the cache" : <number>,
"bytes dirty in the cache cumulative" : <number>,
"bytes read into cache" : <number>,
"bytes written from cache" : <number>,
"checkpoint blocked page eviction" : <number>,
"data source pages selected for eviction unable to be evicted" : <number>,
"eviction walk passes of a file" : <number>,
"eviction walk target pages histogram - 0-9" : <number>,
"eviction walk target pages histogram - 10-31" : <number>,
"eviction walk target pages histogram - 128 and higher" : <number>,
"eviction walk target pages histogram - 32-63" : <number>,
"eviction walk target pages histogram - 64-128" : <number>,
"eviction walks abandoned" : <number>,
"eviction walks gave up because they restarted their walk twice" : <number>,
"eviction walks gave up because they saw too many pages and found no candidates" : <number>,
"eviction walks gave up because they saw too many pages and found too few candidates" : <number>,
"eviction walks reached end of tree" : <number>,
"eviction walks started from root of tree" : <number>,
"eviction walks started from saved location in tree" : <number>,
"hazard pointer blocked page eviction" : <number>,
"in-memory page passed criteria to be split" : <number>,
"in-memory page splits" : <number>,
"internal pages evicted" : <number>,
"internal pages split during eviction" : <number>,
"leaf pages split during eviction" : <number>,
"modified pages evicted" : <number>,
"overflow pages read into cache" : <number>,
"page split during eviction deepened the tree" : <number>,
"page written requiring cache overflow records" : <number>,
"pages read into cache" : <number>,
"pages read into cache after truncate" : <number>,
"pages read into cache after truncate in prepare state" : <number>,
"pages read into cache requiring cache overflow entries" : <number>,
"pages requested from the cache" : <number>,
"pages seen by eviction walk" : <number>,
"pages written from cache" : <number>,
"pages written requiring in-memory restoration" : <number>,
"tracked dirty bytes in the cache" : <number>,
"unmodified pages evicted" : <number>
},
"cache_walk" : {
"Average difference between current eviction generation when the page was last considered" : <number>,
"Average on-disk page image size seen" : <number>,
"Average time in cache for pages that have been visited by the eviction server" : <number>,
"Average time in cache for pages that have not been visited by the eviction server" : <number>,
"Clean pages currently in cache" : <number>,
"Current eviction generation" : <number>,
"Dirty pages currently in cache" : <number>,
"Entries in the root page" : <number>,
"Internal pages currently in cache" : <number>,
"Leaf pages currently in cache" : <number>,
"Maximum difference between current eviction generation when the page was last considered" : <number>,
"Maximum page size seen" : <number>,
"Minimum on-disk page image size seen" : <number>,
"Number of pages never visited by eviction server" : <number>,
"On-disk page image sizes smaller than a single allocation unit" : <number>,
"Pages created in memory and never written" : <number>,
"Pages currently queued for eviction" : <number>,
"Pages that could not be queued for eviction" : <number>,
"Refs skipped during cache traversal" : <number>,
"Size of the root page" : <number>,
"Total number of pages currently in cache" : <number>
},
"compression" : {
"compressed page maximum internal page size prior to compression" : <number>,
"compressed page maximum leaf page size prior to compression " : <number>,
"compressed pages read" : <number>,
"compressed pages written" : <number>,
"page written failed to compress" : <number>,
"page written was too small to compress" : 1
},
"cursor" : {
"bulk loaded cursor insert calls" : <number>,
"cache cursors reuse count" : <number>,
"close calls that result in cache" : <number>,
"create calls" : <number>,
"insert calls" : <number>,
"insert key and value bytes" : <number>,
"modify" : <number>,
"modify key and value bytes affected" : <number>,
"modify value bytes modified" : <number>,
"next calls" : <number>,
"open cursor count" : <number>,
"operation restarted" : <number>,
"prev calls" : <number>,
"remove calls" : <number>,
"remove key bytes removed" : <number>,
"reserve calls" : <number>,
"reset calls" : <number>,
"search calls" : <number>,
"search near calls" : <number>,
"truncate calls" : <number>,
"update calls" : <number>,
"update key and value bytes" : <number>,
"update value size change" : <num>
},
"reconciliation" : {
"dictionary matches" : <number>,
"fast-path pages deleted" : <number>,
"internal page key bytes discarded using suffix compression" : <number>,
"internal page multi-block writes" : <number>,
"internal-page overflow keys" : <number>,
"leaf page key bytes discarded using prefix compression" : <number>,
"leaf page multi-block writes" : <number>,
"leaf-page overflow keys" : <number>,
"maximum blocks required for a page" : <number>,
"overflow values written" : <number>,
"page checksum matches" : <number>,
"page reconciliation calls" : <number>,
"page reconciliation calls for eviction" : <number>,
"pages deleted" : <number>
},
"session" : {
"object compaction" : <number>,
},
"transaction" : {
"update conflicts" : <number>
}
},
"nindexes" : <number>,
"indexDetails" : {
"_id_" : {
"metadata" : {
"formatVersion" : <number>
},
...
},
...
},
"indexBuilds" : [
// Available starting in MongoDB 4.2
<string>,
],
"totalIndexSize" : <number>,
"totalSize" : <number>,
// Available starting in MongoDB 4.4
"indexSizes" : {
"_id_" : <number>,
"<indexName>" : <number>,
...
},
"scaleFactor" : <number> // Available starting in MongoDB 4.2
"ok" : <number>
}
collStats.ns The namespace of the current collection, which follows the format 当前集合的命名空间，格式为[database].[collection].[database].[collection]。
collStats.size The total uncompressed size in memory of all records in a collection. 集合中所有记录在内存中未压缩的总大小。The size does not include the size of any indexes associated with the collection, which the totalIndexSize field reports.size不包括totalIndexSize字段报告的与集合关联的任何索引的大小。
The scale argument affects this value. scale参数会影响此值。Data compression does not affect this value.数据压缩不会影响此值。
collStats.timeseries timeseries appears when you run the collStats command on a time series collection.collStats命令时，将显示timeseries。
This document contains data for internal diagnostic use.本文档包含用于内部诊断的数据。
collStats.avgObjSize The average size of an object in the collection. 集合中对象的平均大小。The scale argument does not affect this value.scale参数不影响此值。
collStats.storageSize The total amount of storage allocated to this collection for document storage. 分配给此集合用于文档存储的存储总量。The scale argument affects this value.scale参数会影响此值。
If collection data is compressed (which is the 如果采集数据被压缩（这是WiredTiger的默认值），则存储大小将反映压缩后的大小，并且可能小于default for WiredTiger), the storage size reflects the compressed size and may be smaller than the value for collStats.size.collStats.size的值。
storageSize does not include index size. 不包括索引大小。See 有关索引大小，请参阅totalIndexSize for index sizing.totalIndexSize。
collStats.freeStorageSize Unavailable for the In-Memory Storage Engine内存中存储引擎不可用
The amount of storage available for reuse. 可重复使用的存储量。The scale argument affects this value.scale参数会影响此值。
The field is only available if storage is available for reuse (i.e. greater than zero).该字段仅在存储可重复使用时可用（即大于零）。
New in version 4.4.在版本4.4中新增。
collStats.nindexes The number of indexes on the collection. 集合上的索引数。All collections have at least one index on the _id field.所有集合在_id字段上至少有一个索引。
Starting in MongoDB 4.2, 从MongoDB 4.2开始，nindexes includes in its count those indexes currently being built.nindexes将当前正在构建的索引包括在内。
collStats.indexDetails A document that reports data from the WiredTiger storage engine for each index in the collection. 报告集合中每个索引的WiredTiger存储引擎数据的文档。Other storage engines will return an empty document.其他存储引擎将返回空文档。
The fields in this document are the names of the indexes, while the values themselves are documents that contain statistics for the index provided by the storage engine. 此文档中的字段是索引的名称，而值本身是包含存储引擎提供的索引统计信息的文档。These statistics are for internal diagnostic use.这些统计数据用于内部诊断。
Starting in MongoDB 4.2, 从MongoDB 4.2开始，indexDetails includes details on indexes currently being built.indexDetails包含当前正在构建的索引的详细信息。
collStats.indexBuilds An array that contains the names of the indexes that are currently being built on the collection. 包含当前正在集合上生成的索引的名称的数组。Once an index build completes, the index does not appear in the 索引生成完成后，索引不会出现在indexBuilds.indexBuilds中。
New in version 4.2.在版本4.2中新增。
collStats.totalIndexSize The total size of all indexes. 所有索引的总大小。The scale argument affects this value.scale参数会影响此值。
If an index uses prefix compression (which is the 如果索引使用前缀压缩（这是WiredTiger的默认值），则在计算总数时，返回的大小将反映任何此类索引的压缩大小。default for WiredTiger), the returned size reflects the compressed size for any such indexes when calculating the total.
Starting in MongoDB 4.2, 从MongoDB 4.2开始，totalIndexSize includes in its total the size of those indexes currently being built.totalIndexSize包含当前正在构建的索引的大小。
collStats.totalSize The sum of the storageSize and totalIndexSize. The scale argument affects this value.storageSize和totalIndexSize的总和。scale参数影响此值。
New in version 4.4.在版本4.4中新增。
collStats.indexSizes This field specifies the key and size of every existing index on the collection. 此字段指定集合中每个现有索引的键和大小。The scale argument affects this value.scale参数会影响此值。
If an index uses prefix compression (which is the 如果索引使用前缀压缩（这是WiredTiger的默认值），则返回的大小将反映压缩后的大小。default for WiredTiger), the returned size reflects the compressed size.
Starting in MongoDB 4.2, 从MongoDB 4.2开始，indexSizes includes sizes of indexes currently being built.indexSizes包括当前正在构建的索引的大小。
collStats.scaleFactor The 命令使用的scale value used by the command.scale值。
If you had specified a non-integer scale factor, MongoDB uses the integer part of the specified factor. 如果指定了非整数比例因子，MongoDB将使用指定因子的整数部分。For example, if you specify a scale factor of 例如，如果指定比例因子1023.999, MongoDB uses 1023 as the scale factor.1023.999，MongoDB将使用1023作为比例因子。
New in version 4.2.在版本4.2中新增。
collStats.max Shows the maximum number of documents that may be present in a capped collection.显示封顶集合中可能存在的最大文档数。
collStats.maxSize Shows the maximum size of a capped collection.显示封顶集合的最大大小。
collStats.wiredTiger wiredTiger only appears when using the WiredTiger storage engine.仅在使用WiredTiger存储引擎时显示。
This document contains data reported directly by the WiredTiger engine and other data for internal diagnostic use.本文档包含WiredTiger引擎直接报告的数据和其他用于内部诊断的数据。
collStats.inMemory inMemory only appears when using the in-memory storage engine.仅在使用内存存储引擎时出现。
This document contains data reported directly by the storage engine and other data for internal diagnostic use.本文档包含存储引擎直接报告的数据和其他供内部诊断使用的数据。