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副本集介绍副本集是什么
- MongoDB复制是将数据同步在多个服务器的过程。
-复制提供了数据的冗余备份,并在多个服务器上存储数据副本,提高了数据的可用性,
并可以保证数据的安全性。 -复制还允许您从硬件故障和服务中断中恢复数据
副本集工作过程
mongodb的复制至少需要两个节点。其中一个是主节点,负责处理客户端请求,
其余的都是从节点,负责复制主节点上的数据。
mongodb各个节点常见的搭配方式为:
一主一从、一主多从。
主节点记录在其上的所有操作oplog,从节点定期轮询主节点获取这些操作,
然后对自己的数据副本执行这些操作,从而保证从节点的数据与主节点一致。
Replica Sets复制集
MongoDB在1.6版本对开发了新功能replica set,这比之前的replication功能要强大一些 ,增加了故障
自动切换和自动修复成员节点,各个DB之间数据完全一致, 大大降低了维护成功。
使用replica set故障切换完全自动。
Replica Sets的结构类似一个集群,完全可以把它当成一个集群,因为它确实与集群实现
的作用是一样的:
如果其中一个节点出现故障,其他节点马上会将业务
接管过来而无须停机操作
Master- Slave主从复制
实现数据同步只需要在某一台服务器启动时加上"master"参数,以指明此服务器的角色
是primary ;另-台服务器加上"-slave‘和" -source参数,以指明此服务器的角色是slave。
.主从复制的优点如下:
从服务器可以执行查询工作,降低主服务器访问压力。-在从服务器执行备份,
避免备份期间锁定主服务器的数据。
当主服务器出现故障时,可以快速切换到从服务器,减少宕机时间。
====================================================================
具体要求:
准备3台mongodb服务器
验证副本集配置
准备三台虚拟机,配置mongodb副本集,ip分别为192.158.4.51, 192.168.4.52,
192.168.4.53其中一个是主节点,负责处理客户端请求,其余的都是从节点,
负责复制主节点上的数据,
实现存储数据副本,提高了数据的可用性,
运行服务
启动服务时,指定主机所在副本集名称 副本集成员间使用形同的副本集名称
[root@server51 ~]# mkdir -p /data/db
[root@server51 ~]# mongod --bind_ip 192.168.200.102 --port 27061 --logpath=/var/l
og/mongod.log --replSet rs1 & //指定副本集名称
[root@server51 ~]#
[root@server51 ~]# netstat -lnpt|grep mongod
tcp 0 0 192.168.200.102:27078 0.0.0.0:* LISTEN 6097/mongod
tcp 0 0 192.168.200.102:27061 0.0.0.0:* LISTEN 6276/mongod
[root@server51 ~]# jobs
[1]+ 运行中 mongod --bind_ip 192.168.200.102 --port 27061 --logpat
h=/var/log/mongod.log --replSet rs1 &
步骤一:创建mongodb副本集
1)三台主机安装mongodb(以4.51为例)
[root@mongodb51 ~]# cd mongodb/
[root@mongodb51 mongodb]# mkdir /usr/local/mongodb
[root@mongodb51 mongodb]# cd /usr/local/mongodb
[root@mongodb51 mongodb]# cp -r \
/root/mongodb/mongodb-linux-x86_64-rhel70-3.6.3/bin/ .
[root@mongodb51 mongodb]# ls
bin
[root@mongodb51 mongodb]# mkdir etc
[root@mongodb51 mongodb]# mkdir log
[root@mongodb51 mongodb]# mkdir -p data/db
[root@mongodb51 mongodb]# vim etc/mongodb.conf
dbpath=/usr/local/mongodb/data/db/
logpath=/usr/local/mongodb/log/mongodb.log
logappend=true
fork=true
bind_ip=192.168.4.51
port=27077
replSet=rs1
//加入到副本集,rs1名字随便起,想知道谁和我在一个副本集里,三台机器的名字一样,都写rs1
2)设置PATH变量
[root@mongodb51 mongodb]# vim /etc/profile
export PATH=/usr/local/mongodb/bin:$PATH
[root@mongodb51 mongodb]# source /etc/profile
3)由于启动和停止服务名字太长,可以起一个别名
给停止服务起一个别名
[root@mongodb51 mongodb]# alias cmdb=‘mongod --dbpath=/usr/local/mongodb/data/db/ --shutdown‘
给启动服务起一个别名
[root@mongodb51 mongodb]# alias smdb=‘mongod -f /usr/local/mongodb/etc/mongodb.conf‘
4)启动服务并连接
[root@mongodb51 ~]# smdb
about to fork child process, waiting until server is ready for connections.
forked process: 5656
child process started successfully, parent exiting
[root@mongodb51 ~]# mongo --host 192.168.4.51 --port 27077
MongoDB shell version v3.6.3
connecting to: mongodb://192.168.4.51:27077/
MongoDB server version: 3.6.3
5)配置集群信息,任意一台都可以,在这里在51上面操作
> rs1_config = { //rs1_config随便起变量名,要记住
_id:"rs1", //必须为rs1这个,三台主机集群名,配置文件里面写的是这个
members:[
{_id:0,host:"192.168.4.51:27077"}, //_id值随意,host值固定
{_id:1,host:"192.168.4.52:27078"},
{_id:2,host:"192.168.4.53:27079"}
]
}; //回车,出现下面情况为成功
{
"_id" : "rs1",
"members" : [
{
"_id" : 0,
"host" : "192.168.4.51:27077"
},
{
"_id" : 1,
"host" : "192.168.4.52:27078"
},
{
"_id" : 2,
"host" : "192.168.4.53:27079"
}
]
}
>
6)初始化Replica Sets环境
> rs.initiate(rs1_config)
{
"ok" : 1,
"operationTime" : Timestamp(1538187475, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1538187475, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
}
}
rs1:SECONDARY>
rs1:PRIMARY> //提示PRIMARY,51为主
工作过程:
Bully算法(有最新操作为主、或者成为主的时间短)
选举 心跳 同步
rs1_config = {
_id:"rs1",
members:[
{_id:0,host:"192.168.4.51:27077",priority:0},
{_id:1,host:"192.168.4.52:27078",priority:3},
{_id:2,host:"192.168.4.53:27079",priority:2}
]
};
7)在52和53上面查看
[root@mongodb52 ~]# mongo --host 192.168.4.52 --port 27078
MongoDB shell version v3.6.3
connecting to: mongodb://192.168.4.52:27078/
MongoDB server version: 3.6.3
...
...
rs1:SECONDARY> //提示SECONDARY,52为从
rs1:SECONDARY>
rs1:SECONDARY>
[root@192 ~]# mongo --host 192.168.4.53 --port 27079
MongoDB shell version v3.6.3
connecting to: mongodb://192.168.4.53:27079/
MongoDB server version: 3.6.3
...
...
rs1:SECONDARY> //提示SECONDARY,53为从
rs1:SECONDARY>
注意:如果初始化错误,重启服务登陆之后重新设置变量,之后再重新初始化
8)查看状态信息
rs1:PRIMARY> rs.status()
...
"members" : [
{
"_id" : 0,
"name" : "192.168.4.51:27077",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 2295,
...
...
},
{
"_id" : 1,
"name" : "192.168.4.52:27078",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 384,
...
...
},
{
"_id" : 2,
"name" : "192.168.4.53:27079",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
...
...
9)查看是否是master库
rs1:PRIMARY> rs .isMaster( )
{
"hosts" : [
"192.168.4.51:27077",
"192.168.4.52:27078",
"192.168.4.53:27079"
],
"setName" : "rs1",
"setVersion" : 1,
"ismaster" : true, //主库
"secondary" : false,
"primary" : "192.168.4.51:27077",
"me" : "192.168.4.51:27077",
...
...
10)验证副本集,同步数据验证(51上面写数据)
rs1:PRIMARY> use gamedb2
switched to db gamedb2
rs1:PRIMARY> db.a.save({name:"yaya",age:75,em:"p@.com"})
WriteResult({ "nInserted" : 1 })
52上面查看
[root@mongodb52 ~]# mongo --host 192.168.4.52 --port 27078
rs1:SECONDARY> db.getMongo().setSlaveOk() //允许从库查看数据
rs1:SECONDARY> show dbs //有gamedb2库
admin 0.000GB
config 0.000GB
ddsdb 0.000GB
gamedb2 0.000GB
local 0.000GB
test 0.000GB
步骤三:切换主库验证
1)自动切换主库验证
关闭51
[root@mongodb51 ~]# cmdb //之前设置的别名
killing process with pid: 5656
查看52和53
[root@mongodb52 ~]# mongo --host 192.168.4.52 --port 27078
MongoDB shell version v3.6.3
connecting to: mongodb://192.168.4.52:27078/
MongoDB server version: 3.6.3
...
...
rs1:PRIMARY> //52为主
rs1:PRIMARY>
[root@mongodb53 ~]# mongo --host 192.168.4.53 --port 27079
MongoDB shell version v3.6.3
connecting to: mongodb://192.168.4.53:27079/
MongoDB server version: 3.6.3
...
...
rs1:SECONDARY> //53为从
启动51,启动后不会再变为主,会成为52的从
[root@mongodb51 ~]# smdb
about to fork child process, waiting until server is ready for connections.
forked process: 6598
child process started successfully, parent exiting
rs1:SECONDARY> rs.isMaster()
{
"hosts" : [
"192.168.4.51:27077",
"192.168.4.52:27078",
"192.168.4.53:27079"
],
"setName" : "rs1",
"setVersion" : 1,
"ismaster" : false,
"secondary" : true,
"primary" : "192.168.4.52:27078",
"me" : "192.168.4.51:27077",
...
==================================
基于MongoDB环境完成下列练习:
插入文档
查询文档
更新文档
删除文档
步骤一:管理文档
1)把系统用户信息/etc/passwd存储到mdb库下的user集合里
rs1:PRIMARY> use mdb
switched to db mdb
rs1:PRIMARY> db.user.save({name:"yaya",password:"x",uid:9999,gid:9999,comment:"",homdir:"/home",shell:"/bin/bash"})
WriteResult({ "nInserted" : 1 })
rs1:PRIMARY> exit
bye
[root@mongodb52 ~]# mongoexport --host 192.168.4.52 --port 27078 -d mdb -c user -f name,password,uid,gid,comment,homdir,shell --type=csv -o /tmp/user.csv
2018-09-29T11:04:14.967+0800 connected to: 192.168.4.52:27078
2018-09-29T11:04:14.968+0800 exported 1 record
[root@mongodb52 ~]# cp /etc/passwd /tmp
[root@mongodb52 ~]# sed -i ‘s/:/,/g‘ /tmp/passwd
[root@mongodb52 ~]# sed -i ‘$r /tmp/passwd‘ /tmp/user.csv
[root@mongodb52 ~]# mongoimport --host 192.168.4.52 --port 27078 -d mdb -c user --headerline --type=csv /tmp/user.csv
2018-09-29T11:06:08.355+0800 connected to: 192.168.4.52:27078
2018-09-29T11:06:08.363+0800 imported 41 documents
2)查看
[root@mongodb52 ~]# mongo --host 192.168.4.52 --port 27078
rs1:PRIMARY> use mdb
switched to db mdb
rs1:PRIMARY> db.user.findOne()
{
"_id" : ObjectId("5baeeb37ce3cc5539aa21f38"),
"name" : "yaya",
"password" : "x",
"uid" : 9999,
"gid" : 9999,
"comment" : "",
"homdir" : "/home",
"shell" : "/bin/bash"
}
db.user.find({条件},{定义显示的字段}) #指定查询条件并指定显示的字段
0不显示 1显示
rs1:PRIMARY> db.user.find()
{ "_id" : ObjectId("5baeeb37ce3cc5539aa21f38"), "name" : "yaya", "password" : "x", "uid" : 9999, "gid" : 9999, "comment" : "", "homdir" : "/home", "shell" : "/bin/bash" }
...
Type "it" for more //出现这个按it,默认出现20行
查看每行的name字段
rs1:PRIMARY> db.user.find({},{name:1})
{ "_id" : ObjectId("5baeeb37ce3cc5539aa21f38"), "name" : "yaya" }
...
...
{ "_id" : ObjectId("5baeec2001805180a1011843"), "name" : "rpc" }
Type "it" for more
不看_id字段
rs1:PRIMARY> db.user.find({},{_id:0})
{ "name" : "yaya", "password" : "x", "uid" : 9999, "gid" : 9999, "comment" : "", "homdir" : "/home", "shell" : "/bin/bash" }
...
...
{ "name" : "rpc", "password" : "x", "uid" : 32, "gid" : 32, "comment" : "Rpcbind Daemon", "homdir" : "/var/lib/rpcbind", "shell" : "/sbin/nologin" }
Type "it" for more
不看_id那一列,看name那一列
rs1:PRIMARY> db.user.find({},{_id:0,name:1})
{ "name" : "yaya" }
...
...
{ "name" : "rpc" }
Type "it" for more
查看以a开头的name字段
rs1:PRIMARY> db.user.find({name:/^a/},{_id:0})
{ "name" : "adm", "password" : "x", "uid" : 3, "gid" : 4, "comment" : "adm", "homdir" : "/var/adm", "shell" : "/sbin/nologin" }
{ "name" : "abrt", "password" : "x", "uid" : 173, "gid" : 173, "comment" : "", "homdir" : "/etc/abrt", "shell" : "/sbin/nologin" }
{ "name" : "avahi", "password" : "x", "uid" : 70, "gid" : 70, "comment" : "Avahi mDNS/DNS-SD Stack", "homdir" : "/var/run/avahi-daemon", "shell" : "/sbin/nologin" }
显示查询结果的前一行
limit 数字
rs1:PRIMARY> db.user.find({name:/^a/},{_id:0}).limit (1)
{ "name" : "adm", "password" : "x", "uid" : 3, "gid" : 4, "comment" : "adm", "homdir" : "/var/adm", "shell" : "/sbin/nologin" }
显示name字段以a开头的第一行
rs1:PRIMARY> db.user.findOne({name:/^a/},{_id:0,name:1,shell:1,uid:1})
{ "name" : "adm", "uid" : 3, "shell" : "/sbin/nologin" }
跳过几行显示 (2行)
skip 数字
rs1:PRIMARY> db.user.find({name:/^a/},{_id:0,name:1,shell:1}).skip (2)
{ "name" : "avahi", "shell" : "/sbin/nologin" }
默认升序排序
sort 字段名
rs1:PRIMARY> db.user.find({name:/^a/},{_id:0,name:1,shell:1,uid:1}).sort({uid:1})
{ "name" : "adm", "uid" : 3, "shell" : "/sbin/nologin" }
{ "name" : "avahi", "uid" : 70, "shell" : "/sbin/nologin" }
{ "name" : "abrt", "uid" : 173, "shell" : "/sbin/nologin" }
降序排序
rs1:PRIMARY> db.user.find({name:/^a/},{_id:0,name:1,shell:1,uid:1}).sort({uid:-1})
{ "name" : "abrt", "uid" : 173, "shell" : "/sbin/nologin" }
{ "name" : "avahi", "uid" : 70, "shell" : "/sbin/nologin" }
{ "name" : "adm", "uid" : 3, "shell" : "/sbin/nologin" }
显示name字段以a开头和uid为3的所有行
rs1:PRIMARY> db.user.find({name:/^a/,uid:3},{_id:0,name:1,shell:1,uid:1})
{ "name" : "adm", "uid" : 3, "shell" : "/sbin/nologin" }
3)条件判断的表示方式
$in 在…里
rs1:PRIMARY> db.user.find({uid:{$in:[1,6,9]}}) //uid的为1或者6或者9的匹配
{ "_id" : ObjectId("5baeec2001805180a1011833"), "name" : "bin", "password" : "x", "uid" : 1, "gid" : 1, "comment" : "bin", "homdir" : "/bin", "shell" : "/sbin/nologin" }
{ "_id" : ObjectId("5baeec2001805180a1011838"), "name" : "shutdown", "password" : "x", "uid" : 6, "gid" : 0, "comment" : "shutdown", "homdir" : "/sbin", "shell" : "/sbin/shutdown" }
$nin 不在…里
rs1:PRIMARY> db.user.find({uid:{$nin:[1,6,9]}},{_id:0,name:1,uid:1})
{ "name" : "yaya", "uid" : 9999 }
...
...
{ "name" : "saslauth", "uid" : 996 }
Type "it" for more
$or 条件满足任意其中一个即可
rs1:PRIMARY> db.user.find({$or:[{name:"root"},{uid:1}]},{_id:0,name:1,uid:1})
{ "name" : "root", "uid" : 0 }
{ "name" : "bin", "uid" : 1 }
4)正则匹配,以a开头的name字段
rs1:PRIMARY> db.user.find({name:/^a/},{_id:0,name:1,uid:1})
{ "name" : "adm", "uid" : 3 }
{ "name" : "abrt", "uid" : 173 }
{ "name" : "avahi", "uid" : 70 }
objectId对象类型 使用12字节的存储空间每个字节2位十六进制数字共计24位字符串.
0 1 2 3 4 5 6 7 8 9 10 11
时间戳 机器 PID 计数器
5)数值比较
$lt(小于) $lte(小于等于) $gt(大于) $gte(大于等于) $ne(不等于)
rs1:PRIMARY> db.user.find({uid:{$gte:10,$lte:40}},{_id:0,name:1,uid:1})
{ "name" : "operator", "uid" : 11 }
{ "name" : "games", "uid" : 12 }
{ "name" : "ftp", "uid" : 14 }
{ "name" : "rpc", "uid" : 32 }
{ "name" : "rpcuser", "uid" : 29 }
{ "name" : "ntp", "uid" : 38 }
匹配null:可以匹配没有的字段,也可以检查这个字段有没有
rs1:PRIMARY> db.user.save({name:null,uid:null})
WriteResult({ "nInserted" : 1 })
rs1:PRIMARY> db.user.find({name:null})
{ "_id" : ObjectId("5baef385f9f3bf625ea1dbd6"), "name" : null, "uid" : null }
rs1:PRIMARY> db.user.find({shell:null}) //表示此条文档没有shell字段
{ "_id" : ObjectId("5baef385f9f3bf625ea1dbd6"), "name" : null, "uid" : null }
6)save和insert的区别
相同点:当集合不存在时创建集合,并插入记录
不同点:
save() _id字段值已经存在时,修改文档字段值
insert() _id字段值已经存在时,放弃修改文档字段值
rs1:PRIMARY> db.t1.save({name:"bob",age:19})
rs1:PRIMARY> db.t1.insert({name:"bob",age:19})
rs1:PRIMARY> db.t1.save({_id:7,name:"bob",age:19})
WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : 7 })
rs1:PRIMARY> db.t1.find()
...
...
{ "_id" : 7, "name" : "bob", "age" : 19 }
rs1:PRIMARY> db.t1.save({_id:7,name:"tom",age:19}) //把上一条的记录直接修改
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
rs1:PRIMARY> db.t1.find()
...
...
{ "_id" : 7, "name" : "tom", "age" : 19 }
rs1:PRIMARY> db.t1.insert({_id:8,name:"tom",age:19}) //可以存上
WriteResult({ "nInserted" : 1 })
rs1:PRIMARY> db.t1.insert({_id:8,name:"tom",age:19}) //存不上
WriteResult({
"nInserted" : 0,
"writeError" : {
"code" : 11000,
"errmsg" : "E11000 duplicate key error collection: mdb.t1 index: _id_ dup key: { : 8.0 }"
}
})
7)插入多行文档
rs1:PRIMARY> db.t1.insertMany([{name:"xiaojiu"},{name:"laoshi"}])
{
"acknowledged" : true,
"insertedIds" : [
ObjectId("5baef526f9f3bf625ea1dbd9"),
ObjectId("5baef526f9f3bf625ea1dbda")
]
}
rs1:PRIMARY> db.t1.find()
...
...
{ "_id" : ObjectId("5baef526f9f3bf625ea1dbd9"), "name" : "xiaojiu" }
{ "_id" : ObjectId("5baef526f9f3bf625ea1dbda"), "name" : "laoshi" }
8)update修改
>db.user.find.update({条件},{修改的字段})
rs1:PRIMARY> db.user.update({name:"root"},{password:"XXX"})
//如果这一列不写完整,这一行除了password这一行,这一列的其他值都没有了
相当于删除(要写完整)
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
rs1:PRIMARY> db.t1.find({name:"root"})
rs1:PRIMARY> db.user.find({name:"root"}) //没有东西,除了password:"XXX"
9)$set 条件匹配时,修改指定字段的值(局部修改)
rs1:PRIMARY> db.user.update({name:"adm"},{$set:{password:"AAA"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
rs1:PRIMARY> db.user.find({name:"adm"}) //还存在
{ "_id" : ObjectId("5baeec2001805180a1011835"), "name" : "adm", "password" : "AAA", "uid" : 3, "gid" : 4, "comment" : "adm", "homdir" : "/var/adm", "shell" : "/sbin/nologin" }
rs1:PRIMARY> db.user.update({name:/^r/},{$set:{password:"FFF"}})
//默认修改匹配条件的第一行
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
rs1:PRIMARY> db.user.update({name:/^a/},{$set:{password:"FFF"}},false,true)
//改匹配到的所有
WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })
10)$unset 删除与条件匹配文档的字段
rs1:PRIMARY> db.user.update({name:"sync"},{$unset:{password:1}})
//删除password字段
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
11)数组
rs1:PRIMARY> db.user.insert({name:"bob",like:["a","b","c","d","e","f",]})
WriteResult({ "nInserted" : 1 })
$pop
删除数组末尾一个元素,1删除最后一个,-1删除第一个
rs1:PRIMARY> db.user.update({name:"bob"},{$pop:{like:1}})
//删除匹配的第一条的最后一个
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
rs1:PRIMARY> db.user.update({name:"bob"},{$pop:{like:-1}})
//删除匹配的第一条的第一个
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
$push 向数组中添加新元素
rs1:PRIMARY> db.user.update({name:"bob"},{$push:{like:"Z"}}) //默认添加到最后
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
rs1:PRIMARY> db.user.update({name:"bob"},{$push:{like:"W"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
rs1:PRIMARY> db.user.find({name:"bob"})
{ "_id" : ObjectId("5baef7b2034891a205de2959"), "name" : "bob", "like" : [ "b", "c", "d", "e", "Z", "W" ] }
$addToSet 避免重复添加
rs1:PRIMARY> db.user.update({name:"bob"},{$addToSet:{like:"W"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })
rs1:PRIMARY> db.user.find({name:"bob"})
{ "_id" : ObjectId("5baef7b2034891a205de2959"), "name" : "bob", "like" : [ "b", "c", "d", "e", "Z", "W" ] }
$pull 删除数组里的指定元素,若有两个bob可以用_id值定义把name:"bob"换成id值
rs1:PRIMARY> db.user.update({name:"bob"},{$pull:{like:"c"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
rs1:PRIMARY> db.user.find({name:"bob"})
{ "_id" : ObjectId("5baef7b2034891a205de2959"), "name" : "bob", "like" : [ "b", "d", "e", "Z", "W" ] }
rs1:PRIMARY> db.user.update({"_id":ObjectId("5afc1a717eff45e9cfc57ed3")},{$push:{like:"S"}})
WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
rs1:PRIMARY>
$inc 条件匹配时,字段值自加或自减
rs1:PRIMARY> db.user.update({uid:{$lte:10}},{$inc:{uid:2}})
//设置字段值自加2,默认改第一行
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
rs1:PRIMARY> db.user.update({uid:{$lte:10}},{$inc:{uid:2}},false,true)
//设置字段值自加2,false,true改全部
WriteResult({ "nMatched" : 8, "nUpserted" : 0, "nModified" : 8 })
rs1:PRIMARY> db.user.update({uid:{$lte:10}},{$inc:{uid:-1}})
//负数时是自减1,默认改第一行
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
12)删除文档
remove()与drop()的区别
remove()删除文档时不删除索引
drop()删除集合的时候同时删除索引
rs1:PRIMARY> db.t1.remove({})
WriteResult({ "nRemoved" : 6 })
rs1:PRIMARY> db.user.remove({name:"/^a/"}) //删除以a开头的记录
WriteResult({ "nRemoved" : 0 })
rs1:PRIMARY> db.t1.drop() //删除集合t1
true
标签:rop 系统 mkdir stack drop 之间 inux write 环境
原文地址:https://blog.51cto.com/14801922/2492398