mongodb 导入导出

(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：

[[email protected] 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
[[email protected] 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：

[[email protected] bin]# ./mongoexport -d foo -c t1 -o /data/t1.json
connected to: 127.0.0.1
exported 1 records
[[email protected] 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：

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

[[email protected] bin]# ./mongoexport -d foo -c t2 --csv -f age,name -o /data/t2.csv
connected to: 127.0.0.1
exported 1 records
[[email protected] bin]#

查看/data/t2.csv的导出结果：

[[email protected] data]# more t2.csv
age,name
1,"wwl"
[[email protected] 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：

[[email protected] 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：

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

[[email protected] 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：

[[email protected] 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 }
>

mongodb 导入导出