1、了解正在进行的操作
> db.currentOp()
{
"inprog" : [
{
"desc" : "conn3", // 与日志信息联系
"threadId" : "140223308420864",
"connectionId" : 3,
"client" : "127.0.0.1:45978", // 操作来源
"appName" : "MongoDB Shell",
"clientMetadata" : {
"application" : {
"name" : "MongoDB Shell"
},
"driver" : {
"name" : "MongoDB Internal Client",
"version" : "3.4.15"
},
"os" : {
"type" : "Linux",
"name" : "CentOS Linux release 7.5.1804 (Core) ",
"architecture" : "x86_64",
"version" : "Kernel 3.10.0-862.el7.x86_64"
}
},
"active" : true, // 是否正在运行
"opid" : 778, // 操作唯一标识，通过它终止一个操作
"secs_running" : 0, // 已经执行的时间
"microsecs_running" : NumberLong(93),
"op" : "command", // 操作的类型：查询、插入、更新、删除；
"ns" : "admin.$cmd",
"query" : {
"currentOp" : 1
},
"numYields" : 0, // 该操作交出锁而使其他操作得以运行的次数
"locks" : { // 该操作使用的锁类型，"^"表示全局锁
},
"waitingForLock" : false, // 表示该操作是否因为正在等待其他操作交出锁而处于阻塞状态
"lockStats" : { // lockStats.timeAcquiringMicros 表示该操作需要多长时间才能取得所需的锁
}
}
],
"ok" : 1
}对于currentOp中的任何字段都可以进行查询，如 db.currentOp({"secs_running": {"$gte": 100}})
根据查找到的opid终止操作的执行
db.killOp(778)一般只有交出了锁的进程才能被终止，正在占用锁或等待交出锁的操作无法被终止；
忽略用于复制的线程和分片中用于回写的监听器，local.oplog.rs长时间运行请求等；
组织幽灵写入最好方式是使用应答式写入，即每次写入操作都会等待上一次写入操作完成后才进行下去，而非在上一次写入进入数据库服务器的缓存区就开始下一次写入；
2、系统分析器system profiler
可查找耗时过长的操作，但开销较大，所以可以定期打开分析器来获取信息；
开启分析器
数据库收到的所有读写请求都将被记录在当前数据库的system.profile集合中；
级别为“2”级，分析器会记录所有内容；
级别为“1”级，只记录长耗时操作，默认时间为100ms，自定义耗时标准，作为第二个参数传入setProfilingLevel()函数即可；
级别为“0”级，关闭分析器；
> use mydb
switched to db mydb
> db.setProfilingLevel(2)
{ "was" : 0, "slowms" : 100, "ok" : 1 }验证分析器
> db.foo.insert({x:1})
WriteResult({ "nInserted" : 1 })
> db.foo.update({},{$set:{x:2}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.foo.remove({})
WriteResult({ "nRemoved" : 1 })> db.system.profile.find().pretty()
{
"op" : "insert",
"ns" : "mydb.foo",
"query" : {
"insert" : "foo",
"documents" : [
{
"_id" : ObjectId("5b04cf5651d72ae1f31dbfa3"),
"x" : 1
}
],
"ordered" : true
},
"ninserted" : 1,
"keysInserted" : 1,
"numYield" : 0,
"locks" : {
"Global" : {
"acquireCount" : {
"r" : NumberLong(3),
"w" : NumberLong(3)
}
},
"Database" : {
"acquireCount" : {
"w" : NumberLong(2),
"W" : NumberLong(1)
}
},
"Collection" : {
"acquireCount" : {
"w" : NumberLong(2)
}
}
},
"responseLength" : 29,
"protocol" : "op_command",
"millis" : 21,
"ts" : ISODate("2018-05-23T02:17:58.993Z"),
"client" : "127.0.0.1",
"appName" : "MongoDB Shell",
"allUsers" : [
{
"user" : "root",
"db" : "admin"
}
],
"user" : "root@admin"
}
{
"op" : "update",
"ns" : "mydb.foo",
"updateobj" : {
"$set" : {
"x" : 2
}
},
"keysExamined" : 0,
"docsExamined" : 1,
"nMatched" : 1,
"nModified" : 1,
"numYield" : 0,
"locks" : {
"Global" : {
"acquireCount" : {
"r" : NumberLong(1),
"w" : NumberLong(1)
}
},
"Database" : {
"acquireCount" : {
"w" : NumberLong(1)
}
},
"Collection" : {
"acquireCount" : {
"w" : NumberLong(1)
}
}
},
"millis" : 0,
"planSummary" : "COLLSCAN",
"execStats" : {
"stage" : "UPDATE",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 3,
"advanced" : 0,
"needTime" : 2,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"nMatched" : 1,
"nWouldModify" : 1,
"nInvalidateSkips" : 0,
"wouldInsert" : false,
"fastmodinsert" : false,
"inputStage" : {
"stage" : "COLLSCAN",
"nReturned" : 1,
"executionTimeMillisEstimate" : 0,
"works" : 2,
"advanced" : 1,
"needTime" : 1,
"needYield" : 0,
"saveState" : 1,
"restoreState" : 1,
"isEOF" : 0,
"invalidates" : 0,
"direction" : "forward",
"docsExamined" : 1
}
},
"ts" : ISODate("2018-05-23T02:18:12.732Z"),
"client" : "127.0.0.1",
"appName" : "MongoDB Shell",
"allUsers" : [
{
"user" : "root",
"db" : "admin"
}
],
"user" : "root@admin"
}
{
"op" : "remove",
"ns" : "mydb.foo",
"keysExamined" : 0,
"docsExamined" : 1,
"ndeleted" : 1,
"keysDeleted" : 1,
"numYield" : 0,
"locks" : {
"Global" : {
"acquireCount" : {
"r" : NumberLong(1),
"w" : NumberLong(1)
}
},
"Database" : {
"acquireCount" : {
"w" : NumberLong(1)
}
},
"Collection" : {
"acquireCount" : {
"w" : NumberLong(1)
}
}
},
"millis" : 0,
"planSummary" : "COLLSCAN",
"execStats" : {
"stage" : "DELETE",
"nReturned" : 0,
"executionTimeMillisEstimate" : 0,
"works" : 3,
"advanced" : 0,
"needTime" : 2,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"nWouldDelete" : 1,
"nInvalidateSkips" : 0,
"inputStage" : {
"stage" : "COLLSCAN",
"nReturned" : 1,
"executionTimeMillisEstimate" : 0,
"works" : 3,
"advanced" : 1,
"needTime" : 1,
"needYield" : 0,
"saveState" : 1,
"restoreState" : 1,
"isEOF" : 1,
"invalidates" : 0,
"direction" : "forward",
"docsExamined" : 1
}
},
"ts" : ISODate("2018-05-23T02:18:27.772Z"),
"client" : "127.0.0.1",
"appName" : "MongoDB Shell",
"allUsers" : [
{
"user" : "root",
"db" : "admin"
}
],
"user" : "root@admin"
}记录耗时超过500ms的操作：
> db.setProfilingLevel(1, 500)
{ "was" : 2, "slowms" : 100, "ok" : 1 }关闭分析器：
> db.setProfilingLevel(0, 100)
{ "was" : 0, "slowms" : 100, "ok" : 1 }即使分析器处于关闭状态，“slowms”也决定哪些操作作为耗时过长的操作被记录到日志中；所以通常情况下，不要将slowms的值设置得过小，如果处于某种需求降低了slowms的值，在关闭分析器前也要将它重新调高；
> db.getProfilingLevel()
03、空间消耗
3.1 返回文档在磁盘上占用字节数，并未包括自动生成的空间间隔 padding和索引；
将_id存储为ObjectId类型比存储为字符串类型效率更高；
> Object.bsonsize({_id:ObjectId()})
22
> Object.bsonsize({_id:""+ObjectId()})
39
> db.foo.findOne()
{ "_id" : ObjectId("5b04d89c51d72ae1f31dbfa6"), "x" : 1 }
> Object.bsonsize(db.foo.findOne())
333.2 集合信息
在使用stats()时传入比例因子scale factor，KB值为1024，MB为1024*1024，依次类推；
> db.foo.stats()
{
"ns" : "mydb.foo", // 命名空间
"size" : 33, // 相当于对此集合中左右元素执行Object.bsonsize()再相加得到的值
"count" : 1,
"avgObjSize" : 33,
"storageSize" : 16384, // 除了文档占用空间、文档间隔、索引，还包含两端预留快速添加新文档的未经使用的空间
"capped" : false,
"wiredTiger" : {
"metadata" : {
"formatVersion" : 1
},
"creationString" : "access_pattern_hint=none,allocation_size=4KB,app_metadata=(formatVersion=1),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_max=15,merge_min=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-1--9139518473434896245",
"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" : 3,
"blocks allocated" : 3,
"blocks freed" : 0,
"checkpoint size" : 4096,
"file allocation unit size" : 4096,
"file bytes available for reuse" : 0,
"file magic number" : 120897,
"file major version number" : 1,
"file size in bytes" : 16384,
"minor version number" : 0
},
"btree" : {
"btree checkpoint generation" : 12,
"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 internal pages" : 0,
"row-store leaf pages" : 0
},
"cache" : {
"bytes currently in the cache" : 883,
"bytes read into cache" : 0,
"bytes written from cache" : 127,
"checkpoint blocked page eviction" : 0,
"data source pages selected for eviction unable to be evicted" : 0,
"hazard pointer blocked page eviction" : 0,
"in-memory page passed criteria to be split" : 0,
"in-memory page splits" : 0,
"internal pages evicted" : 0,
"internal pages split during eviction" : 0,
"leaf pages split during eviction" : 0,
"modified pages evicted" : 1,
"overflow pages read into cache" : 0,
"overflow values cached in memory" : 0,
"page split during eviction deepened the tree" : 0,
"page written requiring lookaside records" : 0,
"pages read into cache" : 0,
"pages read into cache requiring lookaside entries" : 0,
"pages requested from the cache" : 14,
"pages written from cache" : 2,
"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,
"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,
"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 pages read" : 0,
"compressed pages written" : 0,
"page written failed to compress" : 0,
"page written was too small to compress" : 2,
"raw compression call failed, additional data available" : 0,
"raw compression call failed, no additional data available" : 0,
"raw compression call succeeded" : 0
},
"cursor" : {
"bulk-loaded cursor-insert calls" : 0,
"create calls" : 2,
"cursor-insert key and value bytes inserted" : 102,
"cursor-remove key bytes removed" : 1,
"cursor-update value bytes updated" : 0,
"insert calls" : 3,
"next calls" : 6,
"prev calls" : 2,
"remove calls" : 1,
"reset calls" : 13,
"restarted searches" : 0,
"search calls" : 3,
"search near calls" : 2,
"truncate calls" : 0,
"update calls" : 0
},
"reconciliation" : {
"dictionary matches" : 0,
"fast-path pages deleted" : 0,
"internal page key bytes discarded using suffix compression" : 0,
"internal page multi-block writes" : 0,
"internal-page overflow keys" : 0,
"leaf page key bytes discarded using prefix compression" : 0,
"leaf page multi-block writes" : 0,
"leaf-page overflow keys" : 0,
"maximum blocks required for a page" : 0,
"overflow values written" : 0,
"page checksum matches" : 0,
"page reconciliation calls" : 4,
"page reconciliation calls for eviction" : 0,
"pages deleted" : 2
},
"session" : {
"object compaction" : 0,
"open cursor count" : 2
},
"transaction" : {
"update conflicts" : 0
}
},
"nindexes" : 1, // 集合中索引的数量
"totalIndexSize" : 16384,
"indexSizes" : {
"_id_" : 16384
},
"ok" : 1
}3.3 数据库信息
> db.stats()
{
"db" : "mydb", // 数据库名
"collections" : 2, // 包含集合数目
"views" : 0,
"objects" : 5, // 数据库中所有集合包含的文档总数
"avgObjSize" : 656.6,
"dataSize" : 3283, // 数据库中的数据占用的空间大小，不包含空闲列表中的空间，但包含了文档间的间隔；该值与storageSize值的差异为被删除文档的大小
"storageSize" : 32768, // 数据库正在使用的总空间大小
"numExtents" : 0,
"indexes" : 1,
"indexSize" : 16384,
"ok" : 1
}