The difference between MySQL and MongoDB

Summary of the 1.MONGODB

MongoDB (document Database): Provides scalable, high-performance data storage

Overview of 2.MONGODB functions

(1) Based on Distributed file storage

(2) Add more nodes under high load, can guarantee the performance of the server

(3) storing data as a document

Comparison of 3.mongodb and other relational databases

(1) Stability

(2) index, index in memory, can improve the performance of random read and write. If the index is not fully in memory, once the random read and write is high, it will be frequently disk exchange, MongoDB performance will drop sharply

(3) occupies a large space because it belongs to the type of the typical space-time principle. Then its disk space than the ordinary database will be wasted some, and so far it has not implemented online compression function, in MongoDB frequent data additions and deletions, if the record changed, such as the size of the data changed, it is easy to produce some data fragments, the result of fragmentation caused by, One is the index of performance problems, the other is in a certain amount of time after the occupied space will be greatly increased, so to regularly repair the database, periodically re-index, which will improve the stability and efficiency of MongoDB. In the latest version, it has been implemented on-line compression, should be in the 2.0 version around, should be able to achieve online compression, can be performed in the background now repair database of some operations. If that's the case, it solves the big problem that is bothering us.

(4) MongoDB's support for transactional relationships between data is relatively weak

(5) Operation and maintenance is not convenient

Advantages of 4.MongoDB

(1) It is suitable for the requirement model which is not clear to the database specific data format or the database data format changes frequently, and is very friendly to the developer.

(2) with a distributed file system, can be easily deployed to the server cluster. MongoDB has a shard concept, is convenient for the server shard use. The insertion performance of each additional shard,mongodb will also grow in close multiples, and the disk capacity can be easily expanded.

(3) with the support of the Map-reduce computing framework, it is also convenient for data statistics. Similar to GROUP by

5. The difference between MySQL and MongoDB

MongoDB vs. mysql command the traditional relational database is usually composed of three hierarchical concepts of database, table, record,

MongoDB is made up of three levels of databases (database), Collections (collection), document objects (documents).

MongoDB is for tables in relational databases, but there is no concept of columns, rows, and relationships in the collection, which embodies the nature of pattern freedom.

The difference between MySQL and MongoDB