A glance on MongoDB

As other NoSQL Database, MongoDB also to be use as an alternative choice for SQL. And improving more swift.
Document storage style free the programmer from more exactly table design, and give a more soft check for the storage, and preformance high available and scale out storage plan for data
storage. And the replication or relset technology also make the cluster more easily to realize a heavy load service, and the load balance.
One of the sell point is MongoDB will provide a auto-sharding mechinism, so users will take little care about the data sharding, and when the sharding should be take place. On the other
hand, the sharding schedual also could be under control. For Excamle, if your appliction is on a little condition in the late time of the day, you can set the auto-sharding start at 3 am.
MongoDB alse provide a various operation command. And almost the SQL command will find a match command in MonogDB. Select, Update, delet, insert，also could operate in MongoDB. Among the
SQL commander, Select shown as more complex, and have a lot of search condition. But most of them also could be find in MongoDB. Even more, MongoDB also have more smooth command to operate more efficient, for example it could be more convinent to choose the
sequence in the documents, regular experssion also support in the find process.
MongoDB also support the search in the inner document, we could find a inner doucment columus just like it in the outer document. Another one advantage, MongoDB support map-reduce operation,
and the feacture support it for offline date analyse.
Unfortunately,MongoDB not a primitive SQL support, and just with SQL cover. As we know SQL language come from set theme. And one the most important operation is operate between more than
one set. In SQL, it is called as join. and the join operation is the disadvantage in MongoDB.