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。
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: --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 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
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): --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)
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 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.