从mysql导出数据到mongodb数据库

转自：http://www.csser.com/dev/577.html

 

CSSer.com采用的是wordpress程序，数据库为mysql，要想移植到MongoDB数据库，则需要进行数据转换。

数据转移有多种方案，本质上需要将mysql数据转换为一种MongoDB可以直接导入的格式即可。MongoDB提供了mongoimport工具，可以支持导入json,csv的格式。

先来看一下mongoimport支持的参数：

$ 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 ( <set name>/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.

由上面的帮助文档可以看出，采用csv作为中间数据格式，无论对于mysql的导出，还是mongodb的导入，都算得上是成本最低了，于是一回就尝试了一把：

首先，将mysql数据库中的wp-posts表导出，一回偷懒了，直接用phpmyadmin的导出功能，选择csv格式导出，并选中了“删除字段中的换行符”以及“将字段名放在第一行”，保存文件名为csser.csv。

接着，到mongodb服务器，shell下连接MongoDB数据库，并进行数据导入：

$ mongoimport -d csser -c posts -type csv -file csser.csv --headerline
connected to: 127.0.0.1
imported 548 objects

$ mongo
MongoDB shell version: 1.8.1
connecting to: test
> use csser
switched to db csser
> db.posts.count()
547

> db.posts.find({}, {"post_title":1}).sort({"ID":-1}).limit(1)
{ "_id" : ObjectId("4df4641d31b0642fe609426d"), "post_title" : "CSS Sprites在线应用推荐-CSS-sprit" }