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mongodb的导入导出方法

helloworld 发表于 2年前  | 评论(0 )| 阅读次数(639 )|   0 人收藏此文章,   我要收藏

(mongoexport导出工具

MongoDB提供了mongoexport工具,可以把一个collection导出成json格式或csv格式的文件。可以指定导出哪些数据项,也可以根据给定的条件导出数据。工具帮助信息如下:

    [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]#  



下面我们将以一个实际的例子说明,此工具的用法:

将foo库中的表t1导出成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]#  



导出成功后我们看一下/data/t1.json文件的样式,是否是我们所希望的:

    root@localhost data]# more t1.json   
    { "_id" : { "$oid" : "4f927e2385b7a6814a0540a0" }, "age" : 2 }   
    [root@localhost data]#  



通过以上说明导出成功,但有一个问题,要是异构数据库的迁移怎么办呢?例如我们要将MongoDB的数据导入到MySQL该怎么办 呢?MongoDB提供 了一种csv的导出格式,就可以解决异构数据库迁移的问题了. 下面将foo库的t2表的age和name列导出, 具体如下:

    [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的导出结果

    [root@localhost data]# more t2.csv   
    age,name   
    1,"wwl"   
    [root@localhost data]#  



mongoimport导入工具

MongoDB提供了mongoimport工具,可以把一个特定格式文件中的内容导入到某张collection中。工具帮助信息如下:

    [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.  



下面我们将以一人实际的例子说明,此工具的用法:
先看一下foo库中的t1表数据:

    > db.t1.find();   
    { "_id" : ObjectId("4f937a56450beadc560feaa9"), "age" : 5 }   
    >  



t1其中有一条age=5的记录, 我们再看一下json文件中的数据是什么样子的:

    [root@localhost data]# more t1.json   
    { "_id" : { "$oid" : "4f937a56450beadc560feaa7" }, "age" : 8 }   
    [root@localhost data]#  



可以看到t1.json文件中有一条age=8的数据,下面我们将用mongoimport工具将json文件中的记录导入到t1表中:

    [root@localhost bin]# ./mongoimport -d foo -c t1 /data/t1.json   
    connected to: 127.0.0.1   
    imported 1 objects  



工具返回信息说明向表中插入了一条记录. 我们进库里实际验证一下:

    [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 }   
    > 



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