Mongodb redis differences

One 、 summary

MongoDB More like MySQL, Support field index 、where Etc , Its advantage lies in the powerful query function , Good at query JSON data , And can store massive amounts of data , But it doesn't support transactions .

Redis It's open source （BSD The license ） Of , Data structure storage system in memory , Support multiple types of data structures , It can be used as a database , Caching and message queuing agents .

　

Two 、 Specific differences

1、 Memory management mechanism

Redis All data is in memory , Write to disk regularly , When there is not enough memory , You can choose the specified LRU Algorithm delete data .

MongoDB Data exists in memory , from linux System mmap Realization , When there is not enough memory , Just put the hotspot data in memory , Other data is on disk .

2、 Supported data structures

Redis The data structure supported is rich , Include hash、set、list etc. .

MongoDB The data structure is relatively simple , But support rich data expression 、 Indexes , It is very similar to relational database , The supported query statements are very rich .

3、 Data volume and performance

When there is enough physical memory ,Redis>Mongodb>MySQL.

When physical memory is not enough ,Redis and Mongodb Will use virtual memory . however ,Mongodb Dissimilarity , As long as the read-write ratio of hot and cold data can be guaranteed in business , Make the hot data in physical memory ,mmap Less exchange ,mongodb Still guaranteed performance .

4、 performance

Mongodb Dependent on memory ,TPS Higher ;

Redis Dependent on memory ,TPS Very high . On the performance Redis be better than MongoDB.

5、 reliability

mongodb from 1.8 After version , use binlog The way （ And MySQL In the same way ） Support persistence , Increase reliability ;

Redis Depend on snapshot for persistence ;AOF Enhance reliability ; While enhancing reliability , Impact access performance .

Reliability MongoDB be better than Redis.

6、 Data analysis

mongodb Built in data analysis function （mapreduce）; and Redis I won't support it .

7、 Transaction support

Redis Transaction support is weak , It can only guarantee the continuous execution of each operation in the transaction ;mongodb Unsupported transaction .

8、 colony

MongoDB Cluster technology is relatively mature ,Redis from 3.0 Start to support clusters .