mongodb数据库维护离不开必要的备份、恢复操作，而且一般不会出错，所以我们在使用的时候大部分时候使用备份和恢复操作就可以了 mongodump.exe备份的原理是通过一次查询获取当前服务器快照，并将快照写入磁盘中，因此这种方式保存的也不是实时的，因为在获取快照后，服务器还会有数据写入，为了保证备份的安全，同样我们还是可以利用fsync锁使服务器数据暂时写入缓存中。
高效开源数据库(mongodb)下载地址：/softs/41751.html
备份前的检查
> show dbs
MyDB 0.0625GB
admin (empty)
bruce 0.0625GB
local (empty)
test 0.0625GB
> use MyDB
switched to db MyDB
> db.users.find()
{ "_id" : ObjectId("4e290aa39a1945747b28f1ee"), "a" : 1, "b" : 1 }
{ "_id" : ObjectId("4e2cd2182a65c81f21566318"), "a" : 3, "b" : 5 }
>
整库备份：
mongodump -h dbhost -d dbname -o dbdirectory
-h：MongDB所在服务器地址，例如：127.0.0.1，当然也可以指定端口号：127.0.0.1:27017
-d：需要备份的数据库实例，例如：test
-o：备份的数据存放位置，例如：c:\data\dump，当然该目录需要提前建立，在备份完成后，系统自动在dump目录下建立一个test目录，这个目录里面存放该数据库实例的备份数据。
mongodump的官方说明(可通过mongodump --help查看)：options:--helpproduce help message-v [ --verbose ]be more verbose (include multiple times for moreverbosity e.g. -vvvvv)--version print the program's version and exit-h [ --host ] arg mongo host to connect to ( /s1,s2 forsets)--port arg server port. Can also use --host hostname:port--ipv6enable IPv6 support (disabled by default)-u [ --username ] arg username-p [ --password ] arg password--dbpath arg directly access mongod database files in the givenpath, instead of connecting to a mongod server -needs to lock the data directory, so cannot be usedif a mongod is currently accessing the same path--directoryperdbif dbpath specified, each db is in a separatedirectory--journal enable journaling-d [ --db ] argdatabase to use-c [ --collection ] arg collection to use (some commands)-o [ --out ] arg (=dump) output directory or "-" for stdout-q [ --query ] arg json query--oplog Use oplog for point-in-time snapshotting--repair try to recover a crashed database--forceTableScanforce a table scan (do not use $snapshot)
整库恢复：
mongorestore -h dbhost -d dbname –directoryperdb dbdirectory
-h：MongoDB所在服务器地址
-d：需要恢复的数据库实例，例如：test，当然这个名称也可以和备份时候的不一样，比如test2
–directoryperdb：备份数据所在位置，例如：c:\data\dump\test，这里为什么要多加一个test，而不是备份时候的dump，读者自己查看提示吧！
–drop：恢复的时候，先删除当前数据，然后恢复备份的数据。就是说，恢复后，备份后添加修改的数据都会被删除，慎用哦！
mongorestore的官方说明(可通过mongorestore --help查看)：options:--help produce help message-v [ --verbose ] be more verbose (include multiple times for moreverbosity e.g. -vvvvv)--version print the program's version and exit-h [ --host ] arg mongo host to connect to ( /s1,s2 for sets)--port arg server port. Can also use --host hostname:port--ipv6 enable IPv6 support (disabled by default)-u [ --username ] arg username-p [ --password ] arg password--dbpath argdirectly access mongod database files in the givenpath, instead of connecting to a mongod server -needs to lock the data directory, so cannot be usedif a mongod is currently accessing the same path--directoryperdb if dbpath specified, each db is in a separatedirectory--journal enable journaling-d [ --db ] argdatabase to use-c [ --collection ] arg collection to use (some commands)--objcheck validate object before inserting--filter argfilter to apply before inserting--drop drop each collection before import--oplogReplayreplay oplog for point-in-time restore--oplogLimit arg exclude oplog entries newer than provided timestamp(epoch[:ordinal])--keepIndexVersion don't upgrade indexes to newest version--noOptionsRestore don't restore collection options--noIndexRestore don't restore indexes--w arg (=1)minimum number of replicas per write
单个collection备份：
mongoexport -h dbhost -d dbname -c collectionname -f collectionKey -o dbdirectory
-h: MongoDB所在服务器地址
-d: 需要恢复的数据库实例
-c: 需要恢复的集合
-f: 需要导出的字段(省略为所有字段)
-o: 表示导出的文件名
mongoexport的官方说明(可通过mongoexport --help查看)：--helpproduce help message-v [ --verbose ]be more verbose (include multiple times for moreverbosity e.g. -vvvvv)--version print the program's version and exit-h [ --host ] argmongo host to connect to ( /s1,s2 forsets)--port arg server port. Can also use --host hostname:port--ipv6enable IPv6 support (disabled by default)-u [ --username ] arg username-p [ --password ] arg password--dbpath arg directly access mongod database files in the givenpath, instead of connecting to a mongod server -needs to lock the data directory, so cannot be usedif a mongod is currently accessing the same path--directoryperdbif dbpath specified, each db is in a separatedirectory--journal enable journaling-d [ --db ] argdatabase to use-c [ --collection ] arg collection to use (some commands)-f [ --fields ] arg comma separated list of field names e.g. -fname,age--fieldFile argfile with fields names - 1 per line-q [ --query ] arg query filter, as a JSON string--csv export to csv instead of json-o [ --out ] argoutput file; if not specified, stdout is used--jsonArray output to a json array rather than one object perline-k [ --slaveOk ] arg (=1) use secondaries for export if available, defaulttrue--forceTableScanforce a table scan (do not use $snapshot)
单个collection恢复：
mongoimport -d dbhost -c collectionname –type csv –headerline –file
-type: 指明要导入的文件格式
-headerline: 批明不导入第一行，因为第一行是列名
-file: 指明要导入的文件路径
mongoimport的官方说明(可通过mongoimport --help查看)：--help produce help message-v [ --verbose ] be more verbose (include multiple times for moreverbosity e.g. -vvvvv)--version print the program's version and exit-h [ --host ] arg mongo host to connect to ( /s1,s2 for sets)--port arg server port. Can also use --host hostname:port--ipv6 enable IPv6 support (disabled by default)-u [ --username ] arg username-p [ --password ] arg password--dbpath argdirectly access mongod database files in the givenpath, instead of connecting to a mongod server -needs to lock the data directory, so cannot be usedif a mongod is currently accessing the same path--directoryperdb if dbpath specified, each db is in a separatedirectory--journal enable journaling-d [ --db ] argdatabase to use-c [ --collection ] arg collection to use (some commands)-f [ --fields ] arg comma separated list of field names e.g. -f name,age--fieldFile argfile with fields names - 1 per line--ignoreBlanksif given, empty fields in csv and tsv will be ignored--type arg type of file to import. default: json (json,csv,tsv)--file arg file to import from; if not specified stdin is used--drop drop collection first--headerlineCSV,TSV only - use first line as headers--upsert insert or update objects that already exist--upsertFields arg comma-separated fields for the query part of theupsert. You should make sure this is indexed--stopOnErrorstop importing at first error rather than continuing--jsonArray load a json array, not one item per line. Currentlylimited to 16MB.
其他导入与导出操作：
1. mongoimport -d my_mongodb -c user user.dat
参数说明:
-d 指明使用的库, 本例中为” my_mongodb”
-c 指明要导出的表, 本例中为”user”
可以看到导入数据的时候会隐式创建表结构
2. mongoexport -d my_mongodb -c user -o user.dat
参数说明:
-d 指明使用的库, 本例中为” my_mongodb”
-c 指明要导出的表, 本例中为”user”
-o 指明要导出的文件名, 本例中为”user.dat”
从上面可以看到导出的方式使用的是JSON 的样式.
