索引构建情况分析、mongoDB安全（四）

索引好处：加快索引相关的查询

坏处：增加磁盘空间消耗，降低写入性能

评判当前索引构建情况：

1. mongostat工具介绍

2. profile集合介绍

3. 日志介绍

4. explain分析

1. mongostat工具

mongostat：查看MongoDB运行状态程序。

使用：mongostat -h 127.0.0.1:12345

输出字段说明 --help

Fields

inserts - # of inserts per second (* means replicated op)

query - # of queries per second

update - # of updates per second

delete - # of deletes per second

getmore - # of get mores (cursor batch) per second

command - # of commands per second, on a slave its local|replicated

flushes - # of fsync flushes per second

mapped - amount of data mmaped (total data size) megabytes

vsize - virtual size of process in megabytes

res - resident size of process in megabytes

non-mapped - amount virtual memeory less mapped memory (only with --all)

faults - # of pages faults per sec

locked - name of and percent time for most locked database

idx miss - percent of btree page misses (sampled)

qr|qw - queue lengths for clients waiting (read|write)

ar|aw - active clients (read|write)

netIn - network traffic in - bytes

netOut - network traffic out - bytes

conn - number of open connections

set - replica set name

repl - replication type

PRI - primary (master)

SEC - secondary

REC - recovering

UNK - unknown

SLV - slave

b RTR - mongos process ("router")

详细说明参考（http://www.imooc.com/video/6443）

... ...

使用（两个窗口一个添加，一个监控）

添加：

> use jerome

switched to db jerome

> for(i=0;i<100000;i++)db.jerome.insert({x:i})

查看当前系统情况

qr，我们比较关注的，读队列。qw写队列

如果idx miss，比较高存在隐患，可能要构建索引。

2. profile集合

> db.getProfilingStatus() #查看profile设置

{ "was" : 0, "slowms" : 100 }

> db.setProfilingLevel(2) #设置级别

{ "was" : 0, "slowms" : 100, "ok" : 1 }

> db.getProfilingStatus()

{ "was" : 2, "slowms" : 100 }

> show tables #查看生成的集合

jerome

jerome_2

location

system.indexes

system.profile

was分为三个级别：0 1 2

0：关闭。

1：配合slowms，记录所有操作超过slowms的操作。

2：记录任何操作

查看（natural自然排序）

> db.system.profile.find().sort({$naturl:-1}).limit(3)

{ "op" : "query", "ns" : "jerome.system.indexes", "query" : { "expireAfterSeconds" : { "$exists" : true } }, "ntoreturn" : 0, "ntoskip" : 0, "nscanned" : 11, "nscannedObjects" : 11, "keyUpdates" : 0, "numYield" : 0, "lockStats" : { "timeLockedMicros" : { "r" : NumberLong(206), "w" : NumberLong(0) }, "timeAcquiringMicros" : { "r" : NumberLong(4), "w" : NumberLong(7) } }, "nreturned" : 0, "responseLength" : 20, "millis" : 0, "execStats" : { "type" : "COLLSCAN", "works" : 13, "yields" : 0, "unyields" : 0, "invalidates" : 0, "advanced" : 0, "needTime" : 12, "needFetch" : 0, "isEOF" : 1, "docsTested" : 11, "children" : [ ] }, "ts" : ISODate("2015-06-06T09:12:23.021Z"), "client" : "0.0.0.0", "allUsers" : [ { "user" : "__system", "db" : "local" } ], "user" : "__system@local" }

{ "op" : "command", "ns" : "jerome.$cmd", "command" : { "profile" : -1 }, "keyUpdates" : 0, "numYield" : 0, "lockStats" : { "timeLockedMicros" : { "r" : NumberLong(0), "w" : NumberLong(21) }, "timeAcquiringMicros" : { "r" : NumberLong(0), "w" : NumberLong(8) } }, "responseLength" : 58, "millis" : 0, "execStats" : { }, "ts" : ISODate("2015-06-06T09:12:23.051Z"), "client" : "127.0.0.1", "allUsers" : [ ], "user" : "" }

{ "op" : "query", "ns" : "jerome.system.namespaces", "query" : { }, "ntoreturn" : 0, "ntoskip" : 0, "nscanned" : 16, "nscannedObjects" : 16, "keyUpdates" : 0, "numYield" : 0, "lockStats" : { "timeLockedMicros" : { "r" : NumberLong(235), "w" : NumberLong(0) }, "timeAcquiringMicros" : { "r" : NumberLong(7), "w" : NumberLong(7) } }, "nreturned" : 16, "responseLength" : 640, "millis" : 0, "execStats" : { "type" : "COLLSCAN", "works" : 18, "yields" : 0, "unyields" : 0, "invalidates" : 0, "advanced" : 16, "needTime" : 1, "needFetch" : 0, "isEOF" : 1, "docsTested" : 16, "children" : [ ] }, "ts" : ISODate("2015-06-06T09:12:34.167Z"), "client" : "127.0.0.1", "allUsers" : [ ], "user" : "" }

里面参数详细说明（http://www.imooc.com/video/6445）

注意：生产环境一般不使用profile，因为会占据性能。