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mongodb的導入導出方法
(mongoexport導出工具
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MongoDB提供了mongoexport工具，可以把一個collection導出成json格式或csv格式的文件。可以指定導出哪些數(shù)據(jù)項，也可以根據(jù)給定的條件導出數(shù)據(jù)。工具幫助信息如下：
- [root@localhost bin]# ./mongoexport --help
- options:
- --help produce help message
- -v [ --verbose ] be more verbose (include multiple times for more
- verbosity e.g. -vvvvv)
- -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
- -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
- [root@localhost bin]#
下面我們將以一個實際的例子說明，此工具的用法：
將foo庫中的表t1導出成json格式：
- [root@localhost bin]# ./mongoexport -d foo -c t1 -o /data/t1.json
- connected to: 127.0.0.1
- exported 1 records
- [root@localhost bin]#
導出成功后我們看一下/data/t1.json文件的樣式，是否是我們所希望的：
- root@localhost data]# more t1.json
- { "_id" : { "$oid" : "4f927e2385b7a6814a0540a0" }, "age" : 2 }
- [root@localhost data]#
通過以上說明導出成功，但有一個問題，要是異構(gòu)數(shù)據(jù)庫的遷移怎么辦呢?例如我們要將MongoDB的數(shù)據(jù)導入到MySQL該怎么辦呢?MongoDB提供 了一種csv的導出格式，就可以解決異構(gòu)數(shù)據(jù)庫遷移的問題了. 下面將foo庫的t2表的age和name列導出, 具體如下：
- [root@localhost bin]# ./mongoexport -d foo -c t2 --csv -f age,name -o /data/t2.csv
- connected to: 127.0.0.1
- exported 1 records
- [root@localhost bin]#
查看/data/t2.csv的導出結(jié)果
- [root@localhost data]# more t2.csv
- age,name
- 1,"wwl"
- [root@localhost data]#
mongoimport導入工具
MongoDB提供了mongoimport工具，可以把一個特定格式文件中的內(nèi)容導入到某張collection中。工具幫助信息如下：
- [root@localhost bin]# ./mongoimport --help
- options:
- --help produce help message
- -v [ --verbose ] be more verbose (include multiple times for more
- verbosity e.g. -vvvvv)
- -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
- -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 4MB.
下面我們將以一人實際的例子說明，此工具的用法：
先看一下foo庫中的t1表數(shù)據(jù)：
- > db.t1.find();
- { "_id" : ObjectId("4f937a56450beadc560feaa9"), "age" : 5 }
- >
t1其中有一條age=5的記錄, 我們再看一下json文件中的數(shù)據(jù)是什么樣子的：
- [root@localhost data]# more t1.json
- { "_id" : { "$oid" : "4f937a56450beadc560feaa7" }, "age" : 8 }
- [root@localhost data]#
可以看到t1.json文件中有一條age=8的數(shù)據(jù)，下面我們將用mongoimport工具將json文件中的記錄導入到t1表中：
- [root@localhost bin]# ./mongoimport -d foo -c t1 /data/t1.json
- connected to: 127.0.0.1
- imported 1 objects
工具返回信息說明向表中插入了一條記錄. 我們進庫里實際驗證一下：
- [root@localhost bin]# ./mongo
- MongoDB shell version: 1.8.1
- connecting to: test
- > use foo
- switched to db foo
- > db.t1.find();
- { "_id" : ObjectId("4f937a56450beadc560feaa9"), "age" : 5 }
- { "_id" : ObjectId("4f937a56450beadc560feaa7"), "age" : 8 }
- >
新聞名稱：mongodb的導入導出方法
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