mongodump.exe備份的原理是通過一次查詢獲取當前服務器快照，并將快照寫入磁盤中，因此這種方式保存的也不是實時的，因為在獲取快照后，服務器還會有數(shù)據(jù)寫入，為了保證備份的安全，同樣我們還是可以利用fsync鎖使服務器數(shù)據(jù)暫時寫入緩存中。
備份前的檢查
> 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 }
>
整庫備份：
mongodump -h dbhost -d dbname -o dbdirectory
-h：MongDB所在服務器地址，例如：127.0.0.1，當然也可以指定端口號：127.0.0.1:27017
-d：需要備份的數(shù)據(jù)庫實例，例如：test
-o：備份的數(shù)據(jù)存放位置，例如：c:\data\dump，當然該目錄需要提前建立，在備份完成后，系統(tǒng)自動在dump目錄下建立一個test目錄，這個目錄里面存放該數(shù)據(jù)庫實例的備份數(shù)據(jù)。
mongodump的官方說明(可通過mongodump --help查看)：
options:
--help produce help message
-v [ --verbose ] be more verbose (include multiple times for more
verbosity 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 arg directly access mongod database files in the given
path, instead of connecting to a mongod server -
needs to lock the data directory, so cannot be used
if a mongod is currently accessing the same path
--directoryperdb if dbpath specified, each db is in a separate
directory
--journal enable journaling
-d [ --db ] arg database 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
--forceTableScan force a table scan (do not use $snapshot)
整庫恢復：
mongorestore -h dbhost -d dbname –directoryperdb dbdirectory
-h：MongoDB所在服務器地址
-d：需要恢復的數(shù)據(jù)庫實例，例如：test，當然這個名稱也可以和備份時候的不一樣，比如test2
–directoryperdb：備份數(shù)據(jù)所在位置，例如：c:\data\dump\test，這里為什么要多加一個test，而不是備份時候的dump，讀者自己查看提示吧！
–drop：恢復的時候，先刪除當前數(shù)據(jù)，然后恢復備份的數(shù)據(jù)。就是說，恢復后，備份后添加修改的數(shù)據(jù)都會被刪除，慎用哦！
mongorestore的官方說明(可通過mongorestore --help查看)：
options:
--help produce help message
-v [ --verbose ] be more verbose (include multiple times for more
verbosity 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 arg directly access mongod database files in the given
path, instead of connecting to a mongod server -
needs to lock the data directory, so cannot be used
if a mongod is currently accessing the same path
--directoryperdb if dbpath specified, each db is in a separate
directory
--journal enable journaling
-d [ --db ] arg database to use
-c [ --collection ] arg collection to use (some commands)
--objcheck validate object before inserting
--filter arg filter to apply before inserting
--drop drop each collection before import
--oplogReplay replay 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
單個collection備份：
mongoexport -h dbhost -d dbname -c collectionname -f collectionKey -o dbdirectory
-h: MongoDB所在服務器地址
-d: 需要恢復的數(shù)據(jù)庫實例
-c: 需要恢復的集合
-f: 需要導出的字段(省略為所有字段)
-o: 表示導出的文件名
mongoexport的官方說明(可通過mongoexport --help查看)：
--help produce help message
-v [ --verbose ] be more verbose (include multiple times for more
verbosity 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 arg directly access mongod database files in the given
path, instead of connecting to a mongod server -
needs to lock the data directory, so cannot be used
if a mongod is currently accessing the same path
--directoryperdb if dbpath specified, each db is in a separate
directory
--journal enable journaling
-d [ --db ] arg database 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 arg file with fields names - 1 per line
-q [ --query ] arg query filter, as a JSON string
--csv export to csv instead of json
-o [ --out ] arg output file; if not specified, stdout is used
--jsonArray output to a json array rather than one object per
line
-k [ --slaveOk ] arg (=1) use secondaries for export if available, default
true
--forceTableScan force a table scan (do not use $snapshot)
單個collection恢復：
mongoimport -d dbhost -c collectionname –type csv –headerline –file
-type: 指明要導入的文件格式
-headerline: 批明不導入第一行，因為第一行是列名
-file: 指明要導入的文件路徑
mongoimport的官方說明(可通過mongoimport --help查看)：
--help produce help message
-v [ --verbose ] be more verbose (include multiple times for more
verbosity 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 arg directly access mongod database files in the given
path, instead of connecting to a mongod server -
needs to lock the data directory, so cannot be used
if a mongod is currently accessing the same path
--directoryperdb if dbpath specified, each db is in a separate
directory
--journal enable journaling
-d [ --db ] arg database 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 arg file with fields names - 1 per line
--ignoreBlanks if 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
--headerline CSV,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 the
upsert. You should make sure this is indexed
--stopOnError stop importing at first error rather than continuing
--jsonArray load a json array, not one item per line. Currently
limited to 16MB.
其他導入與導出操作：
1. mongoimport -d my_mongodb -c user user.dat
參數(shù)說明:
-d 指明使用的庫, 本例中為” my_mongodb”
-c 指明要導出的表, 本例中為”user”
可以看到導入數(shù)據(jù)的時候會隱式創(chuàng)建表結構
2. mongoexport -d my_mongodb -c user -o user.dat
參數(shù)說明:
-d 指明使用的庫, 本例中為” my_mongodb”
-c 指明要導出的表, 本例中為”user”
-o 指明要導出的文件名, 本例中為”user.dat”
從上面可以看到導出的方式使用的是JSON 的樣式.
