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db.collection.stats()
定义
使用 $collStats聚合阶段而不是collStats命令及其 mongosh辅助方法db.collection.stats() 。
db.collection.stats(<option>)重要
mongosh 方法
本页介绍了
mongosh方法。这不是数据库命令或特定语言驱动程序（例如 Node.js）的文档。有关数据库命令，请参阅
collStats命令。对于 MongoDB API 驱动程序，请参阅特定语言的MongoDB 驱动程序文档。
对于传统
mongoShell 文档，请参阅相应 MongoDB Server 版本的文档：返回有关集合的统计信息。
方法的格式如下：
db.collection.stats({ scale: <num>, // Optional indexDetails: <boolean>, // Optional indexDetailsKey: <document>, // Optional indexDetailsName: <string>. // Optional }) 字段类型说明scale数字可选。各种大小数据的比例因子。
scale默认为 1，以字节为单位返回大小数据。要显示千字节而不是字节，请指定1024的scale值。如果指定了非整数比例因子，MongoDB 将使用该因子的整数部分。例如，如果指定比例因子为
1023.999，MongoDB 将使用1023作为比例因子。从版本 4.2 开始，输出包括用于缩放大小值的
scaleFactor。indexDetails布尔可选。如果
true，db.collection.stats()除了集合统计信息外还返回index details。仅适用于 WiredTiger 存储引擎。
默认值为
false。indexDetailsKey文档可选。如果
indexDetails为true，可以使用indexDetailsKey通过指定索引键规范来筛选索引详情。仅返回与indexDetailsKey精确匹配的索引。如果未找到匹配项，
indexDetails将显示所有索引的统计数据。使用
getIndexes()发现索引键。不能将indexDetailsKey与indexDetailsName一起使用。indexDetailsName字符串可选。如果
indexDetails为true，您可以通过指定索引name使用indexDetailsName来筛选索引详细信息。仅返回与indexDetailsName完全匹配的索引名称。如果未找到匹配项，
indexDetails将显示所有索引的统计数据。使用
getIndexes()查找索引名称。不能将indexDetailsName与indexDetailsField一起使用。如要仅指定
scale因素，MongoDB 支持旧格式：db.collection.stats(<number>) 返回： 一份包含指定集合的统计信息的文档。请参阅 collStats，了解返回统计数据的明细。
行为
缩放的大小
除非指标名称另有指定（例如 "bytes
currently in the cache"），否则与大小相关的值以字节为单位显示，并且可以被 scale 覆盖。
比例因子会将受影响的大小值四舍五入为整数。
引擎加密
根据存储引擎的不同，返回的数据可能会有所不同。有关字段的详细信息，请参阅输出详情。
意外关闭后的准确性
mongod使用 Wired Tiger 存储引擎非正常关闭 后，db.collection.stats() 报告的计数和大小统计信息可能不准确。
偏差的大小取决于在最后一个检查点和非正常关闭之间执行的插入、更新或删除操作的次数。检查点通常每 60 秒出现一次。但是，如果 mongod 实例使用了非默认的 --syncdelay 设置，则检查点出现的次数可能会增多或减少。
在 mongod 的每个集合上运行 validate，以在非正常关闭之后恢复统计信息。
非正常关闭后：
副本集节点状态限制
要在副本集成员上运行， collStats操作要求该成员处于PRIMARY或SECONDARY状态。如果节点处于其他状态，例如STARTUP2 ，则操作错误。
索引筛选器行为
使用 indexDetailsKey 或 indexDetailsName 对 indexDetails 进行过滤只会返回一个匹配索引。如果未找到完全匹配项，indexDetails 将显示该集合所有索引的相关信息。
indexDetailsKey 字段采用以下格式的文档：
{ '<string>' : <value>, '<string>' : <value>, ... }
其中，<string>> 为对其创建索引的字段，而 <value> 为此索引的方向或是某一特殊索引类型，例如 text 或 2dsphere。请参阅索引类型以查看索引类型的完整列表。
意外关闭和计数
对于使用 WiredTiger 存储引擎的 MongoDB 实例，在非正常关闭后，有关大小和计数的统计信息可能会最多减少 1000 份文档，如 collStats、dbStats、count 报告所示。要为集合恢复正确的统计信息，请对该集合运行 validate。
进行中的索引
从 MongoDB 4开始。 2 ， db.collection.stats()包括有关当前正在构建的索引的信息。有关详细信息，请参阅：
举例
注意
基本统计信息查询
以下操作将返回有关 test 数据库中的 restaurants 集合的统计信息：
db.restaurants.stats()
该操作返回：
{ "ns" : "test.restaurants", "size" : 7557340, "count" : 25359, "avgObjSize" : 298, "storageSize" : 9670656, "freeStorageSize" : 6660096, "capped" : false, "wiredTiger" : { "metadata" : { "formatVersion" : 1 }, "creationString" : "access_pattern_hint=none,allocation_size=4KB,app_metadata=(formatVersion=1),assert=(commit_timestamp=none,durable_timestamp=none,read_timestamp=none),block_allocation=best,block_compressor=snappy,cache_resident=false,checksum=on,colgroups=,collator=,columns=,dictionary=0,encryption=(keyid=,name=),exclusive=false,extractor=,format=btree,huffman_key=,huffman_value=,ignore_in_memory_cache_size=false,immutable=false,internal_item_max=0,internal_key_max=0,internal_key_truncate=true,internal_page_max=4KB,key_format=q,key_gap=10,leaf_item_max=0,leaf_key_max=0,leaf_page_max=32KB,leaf_value_max=64MB,log=(enabled=true),lsm=(auto_throttle=true,bloom=true,bloom_bit_count=16,bloom_config=,bloom_hash_count=8,bloom_oldest=false,chunk_count_limit=0,chunk_max=5GB,chunk_size=10MB,merge_custom=(prefix=,start_generation=0,suffix=),merge_max=15,merge_min=0),memory_page_image_max=0,memory_page_max=10m,os_cache_dirty_max=0,os_cache_max=0,prefix_compression=false,prefix_compression_min=4,source=,split_deepen_min_child=0,split_deepen_per_child=0,split_pct=90,type=file,value_format=u", "type" : "file", "uri" : "statistics:table:collection-43-6797839137631957852", "LSM" : { "bloom filter false positives" : 0, "bloom filter hits" : 0, "bloom filter misses" : 0, "bloom filter pages evicted from cache" : 0, "bloom filter pages read into cache" : 0, "bloom filters in the LSM tree" : 0, "chunks in the LSM tree" : 0, "highest merge generation in the LSM tree" : 0, "queries that could have benefited from a Bloom filter that did not exist" : 0, "sleep for LSM checkpoint throttle" : 0, "sleep for LSM merge throttle" : 0, "total size of bloom filters" : 0 }, "block-manager" : { "allocations requiring file extension" : 460, "blocks allocated" : 556, "blocks freed" : 420, "checkpoint size" : 2994176, "file allocation unit size" : 4096, "file bytes available for reuse" : 6660096, "file magic number" : 120897, "file major version number" : 1, "file size in bytes" : 9670656, "minor version number" : 0 }, "btree" : { "btree checkpoint generation" : 58, "column-store fixed-size leaf pages" : 0, "column-store internal pages" : 0, "column-store variable-size RLE encoded values" : 0, "column-store variable-size deleted values" : 0, "column-store variable-size leaf pages" : 0, "fixed-record size" : 0, "maximum internal page key size" : 368, "maximum internal page size" : 4096, "maximum leaf page key size" : 2867, "maximum leaf page size" : 32768, "maximum leaf page value size" : 67108864, "maximum tree depth" : 3, "number of key/value pairs" : 0, "overflow pages" : 0, "pages rewritten by compaction" : 0, "row-store empty values" : 0, "row-store internal pages" : 0, "row-store leaf pages" : 0 }, "cache" : { "bytes currently in the cache" : 19401033, "bytes dirty in the cache cumulative" : 28415209, "bytes read into cache" : 0, "bytes written from cache" : 31893695, "checkpoint blocked page eviction" : 0, "data source pages selected for eviction unable to be evicted" : 0, "eviction walk passes of a file" : 0, "eviction walk target pages histogram - 0-9" : 0, "eviction walk target pages histogram - 10-31" : 0, "eviction walk target pages histogram - 128 and higher" : 0, "eviction walk target pages histogram - 32-63" : 0, "eviction walk target pages histogram - 64-128" : 0, "eviction walks abandoned" : 0, "eviction walks gave up because they restarted their walk twice" : 0, "eviction walks gave up because they saw too many pages and found no candidates" : 0, "eviction walks gave up because they saw too many pages and found too few candidates" : 0, "eviction walks reached end of tree" : 0, "eviction walks started from root of tree" : 0, "eviction walks started from saved location in tree" : 0, "hazard pointer blocked page eviction" : 0, "in-memory page passed criteria to be split" : 4, "in-memory page splits" : 2, "internal pages evicted" : 0, "internal pages split during eviction" : 0, "leaf pages split during eviction" : 2, "modified pages evicted" : 2, "overflow pages read into cache" : 0, "page split during eviction deepened the tree" : 0, "page written requiring cache overflow records" : 0, "pages read into cache" : 0, "pages read into cache after truncate" : 1, "pages read into cache after truncate in prepare state" : 0, "pages read into cache requiring cache overflow entries" : 0, "pages requested from the cache" : 76607, "pages seen by eviction walk" : 0, "pages written from cache" : 552, "pages written requiring in-memory restoration" : 0, "tracked dirty bytes in the cache" : 0, "unmodified pages evicted" : 0 }, "cache_walk" : { "Average difference between current eviction generation when the page was last considered" : 0, "Average on-disk page image size seen" : 0, "Average time in cache for pages that have been visited by the eviction server" : 0, "Average time in cache for pages that have not been visited by the eviction server" : 0, "Clean pages currently in cache" : 0, "Current eviction generation" : 0, "Dirty pages currently in cache" : 0, "Entries in the root page" : 0, "Internal pages currently in cache" : 0, "Leaf pages currently in cache" : 0, "Maximum difference between current eviction generation when the page was last considered" : 0, "Maximum page size seen" : 0, "Minimum on-disk page image size seen" : 0, "Number of pages never visited by eviction server" : 0, "On-disk page image sizes smaller than a single allocation unit" : 0, "Pages created in memory and never written" : 0, "Pages currently queued for eviction" : 0, "Pages that could not be queued for eviction" : 0, "Refs skipped during cache traversal" : 0, "Size of the root page" : 0, "Total number of pages currently in cache" : 0 }, "compression" : { "compressed page maximum internal page size prior to compression" : 4096, "compressed page maximum leaf page size prior to compression " : 111392, "compressed pages read" : 0, "compressed pages written" : 548, "page written failed to compress" : 0, "page written was too small to compress" : 4 }, "cursor" : { "bulk loaded cursor insert calls" : 0, "cache cursors reuse count" : 74, "close calls that result in cache" : 0, "create calls" : 4, "insert calls" : 50718, "insert key and value bytes" : 24500283, "modify" : 0, "modify key and value bytes affected" : 0, "modify value bytes modified" : 0, "next calls" : 101747, "open cursor count" : 0, "operation restarted" : 0, "prev calls" : 1, "remove calls" : 0, "remove key bytes removed" : 0, "reserve calls" : 0, "reset calls" : 51000, "search calls" : 25359, "search near calls" : 25485, "truncate calls" : 0, "update calls" : 0, "update key and value bytes" : 0, "update value size change" : 0 }, "reconciliation" : { "dictionary matches" : 0, "fast-path pages deleted" : 0, "internal page key bytes discarded using suffix compression" : 1077, "internal page multi-block writes" : 1, "internal-page overflow keys" : 0, "leaf page key bytes discarded using prefix compression" : 0, "leaf page multi-block writes" : 12, "leaf-page overflow keys" : 0, "maximum blocks required for a page" : 1, "overflow values written" : 0, "page checksum matches" : 0, "page reconciliation calls" : 80, "page reconciliation calls for eviction" : 2, "pages deleted" : 0 }, "session" : { "object compaction" : 0 }, "transaction" : { "update conflicts" : 0 } }, "nindexes" : 4, "indexBuilds" : [ ], // Available starting in MongoDB 4.2 "totalIndexSize" : 704512, "totalSize" : 10375168, "indexSizes" : { "_id_" : 241664, "cuisine_1" : 147456, "borough_1_cuisine_1" : 159744, "borough_1_address.zipcode_1" : 155648 }, "scaleFactor" : 1, // Available starting in MongoDB 4.2 "ok" : 1 }
由于 stats 未提供比例参数，因此所有大小值均以bytes为单位。
使用比例表查询统计数据
以下操作通过指定scale为1024将数据规模从bytes更改为kilobytes：
db.restaurants.stats( { scale : 1024 } )
该操作返回：
{ "ns" : "test.restaurants", "size" : 7380, "count" : 25359, "avgObjSize" : 298, "storageSize" : 9444, "freeStorageSize" : 6504, "capped" : false, "wiredTiger" : { ... }, "nindexes" : 4, "indexBuilds" : [ ], // Available starting in MongoDB 4.2 "totalIndexSize" : 688, "totalSize" : 10132, "indexSizes" : { "_id_" : 236, "cuisine_1" : 144, "borough_1_cuisine_1" : 156, "borough_1_address.zipcode_1" : 152 }, "scaleFactor" : 1024, // Available starting in MongoDB 4.2 "ok" : 1 }
附带索引详细信息的统计信息查找
以下操作创建一份 indexDetails 文档，其中包含与集合中每个索引相关的信息：
db.restaurants.stats( { indexDetails : true } )
该操作返回：
{ "ns" : "test.restaurants", "size" : 7557340, "count" : 25359, "avgObjSize" : 298, "storageSize" : 9670656, "freeStorageSize" : 6660096, "capped" : false, "wiredTiger" : { ... }, "nindexes" : 4, "indexDetails" : { "_id_" : { "metadata" : { "formatVersion" : 8 }, "creationString" : "access_pattern_hint=none,allocation_size=4KB,app_metadata=(formatVersion=8),assert=(commit_timestamp=none,durable_timestamp=none,read_timestamp=none),block_allocation=best,block_compressor=,cache_resident=false,checksum=on,colgroups=,collator=,columns=,dictionary=0,encryption=(keyid=,name=),exclusive=false,extractor=,format=btree,huffman_key=,huffman_value=,ignore_in_memory_cache_size=false,immutable=false,internal_item_max=0,internal_key_max=0,internal_key_truncate=true,internal_page_max=16k,key_format=u,key_gap=10,leaf_item_max=0,leaf_key_max=0,leaf_page_max=16k,leaf_value_max=0,log=(enabled=true),lsm=(auto_throttle=true,bloom=true,bloom_bit_count=16,bloom_config=,bloom_hash_count=8,bloom_oldest=false,chunk_count_limit=0,chunk_max=5GB,chunk_size=10MB,merge_custom=(prefix=,start_generation=0,suffix=),merge_max=15,merge_min=0),memory_page_image_max=0,memory_page_max=5MB,os_cache_dirty_max=0,os_cache_max=0,prefix_compression=true,prefix_compression_min=4,source=,split_deepen_min_child=0,split_deepen_per_child=0,split_pct=90,type=file,value_format=u", "type" : "file", "uri" : "statistics:table:index-44-6797839137631957852", "LSM" : { ... }, "block-manager" : { ... }, "btree" : { ... }, "cache" : { ... }, "cache_walk" : { ... }, "compression" : { ... }, "cursor" : { ... }, "reconciliation" : { ... }, "session" : { ... }, "transaction" : { ... } }, "cuisine_1" : { ... }, "borough_1_cuisine_1" : { ... }, "borough_1_address.zipcode_1" : { ... }, "indexBuilds" : [ ], // Available starting in MongoDB 4.2 "totalIndexSize" : 704512, "totalSize" : 10375168, "indexSizes" : { "_id_" : 241664, "cuisine_1" : 147456, "borough_1_cuisine_1" : 159744, "borough_1_address.zipcode_1" : 155648 }, "scaleFactor" : 1, // Available starting in MongoDB 4.2 "ok" : 1 }
附带筛选后索引详细信息的统计信息查找
要过滤 indexDetails 字段中的索引，您可以使用 indexDetailsKey 选项指定索引键，也可以使用 indexDetailsName 指定索引名称。若要发现集合的索引键和名称，请使用 db.collection.getIndexes()。
给定以下索引：
{ "ns" : "test.restaurants", "v" : 1, "key" : { "borough" : 1, "cuisine" : 1 }, "name" : "borough_1_cuisine_1" }
以下操作将 indexDetails 文档过滤为由 indexDetailsKey 文档定义的单个索引。
db.restaurants.stats( { 'indexDetails' : true, 'indexDetailsKey' : { 'borough' : 1, 'cuisine' : 1 } } )
以下操作将 indexDetails 文档过滤为由 indexDetailsName 文档定义的单个索引。
db.restaurants.stats( { 'indexDetails' : true, 'indexDetailsName' : 'borough_1_cuisine_1' } )
这两个操作将返回相同的输出：
{ "ns" : "test.restaurants", "size" : 7557340, "count" : 25359, "avgObjSize" : 298, "storageSize" : 9670656, "freeStorageSize" : 6660096, "capped" : false, "wiredTiger" : { ... }, "nindexes" : 4, "indexDetails" : { "borough_1_cuisine_1" : { "metadata" : { "formatVersion" : 8 }, "LSM" : { ... }, "block-manager" : { ... }, "btree" : { ... }, "cache" : { ... }, "cache_walk" : { ... }, "compression" : { ... }, "cursor" : { ... }, "reconciliation" : { ... }, "session" : { ... }, "transaction" : { ... } } }, "indexBuilds" : [ ], // Available starting in MongoDB 4.2 "totalIndexSize" : 704512, "totalSize" : 10375168, "indexSizes" : { "_id_" : 241664, "cuisine_1" : 147456, "borough_1_cuisine_1" : 159744, "borough_1_address.zipcode_1" : 155648 }, "scaleFactor" : 1, // Available starting in MongoDB 4.2 "ok" : 1 }
有关输出的解释，请参阅输出详情。