MongoDB and Redis differences

Brief introduction

MongoDB is more like MySQL, support field index, cursor operation, the advantage is that the query is more powerful, good at querying JSON data, can store large amounts of data, but does not support transactions.

MySQL is significantly less efficient when it comes to large data volumes, and MongoDB is more of a substitute for relational databases.

Memory management mechanism

The Redis data all exists in memory and is written to disk on a regular basis, and when memory is insufficient, the specified LRU algorithm can be selected to delete the data.

MongoDB data exists in memory, implemented by Linux system Mmap, when the memory is not enough, only the hotspot data into memory, the other data exists disk.

Supported data structures

Redis supports rich data structures, including hash, set, list, and so on.

MONGODB data structure is relatively single, but support rich data expression, index, most similar relational database, support query language is very rich.

Performance

Both performance is relatively high, should say is not a bottleneck.

Reliability

Both of them support persistence.

Cluster

MongoDB clustering technology is relatively mature, Redis starting from 3.0 support cluster.

Scenario Not applicable

? Operations that require the use of complex SQL

? Transactional systems

Both MongoDB and Redis are NoSQL, using structured data storage. There are some differences between the two in the usage scene, which is mainly due to the process of the memory mapping, and the persistence processing method is different.

MongoDB recommended cluster deployment, more considering the cluster scenario, Redis is more emphasis on process sequential write, although the support cluster, but also limited to the master-slave mode.

Compare indicators	MongoDB (v2.4.9)	Redis (v2.4.17)	Comparison notes
Implementation language	C++	C + +	-
Agreement	BSON, Custom Binary	Class Telnet	-
Performance	Memory dependent, higher TPS	Memory dependent, TPS very high	Redis is better than MongoDB
operability	Rich data expression, index, most similar to relational database, support rich query statement	Data-rich, less IO	MongoDB is better than Redis
Memory and Storage	Suitable for large data volume storage, dependent on system virtual memory, image file storage, high memory consumption ratio, the official recommended independent deployment in 64-bit system	REDIS2.0 supports virtual memory features (VMS) Beyond physical memory limits, data can be set to timeliness, similar to Memcache	Different application scenarios
Availability of	Support Master-slave,replicatset (internal use of Paxos election algorithm, automatic failback), auto sharding mechanism, blocking the failover and slicing mechanism to the client	Rely on the client to implement the distributed read and write, master-slave replication, every time from the node reconnect to the primary node to rely on the entire snapshot, no incremental replication; auto sharding is not supported, need to rely on the program to set the consistency hash mechanism	MongoDB is better than Redis; On a single point problem, MongoDB application is simple, relative user transparent, Redis is more complex, need the client to actively solve. (MongoDB is typically combined with replicasets and sharding, replicasets focus on high availability and high reliability, sharding focus on performance, horizontal scaling)
Reliability	Support for persistence in Binlog mode (MySQL-like) since version 1.8	Rely on snapshots for persistence; AOF enhances reliability and enhances performance while impacting access
Consistency	Transactions are not supported, guaranteed by the client	Support transactions, more brittle, only ensure that operations in the transaction are executed sequentially	Redis is better than MongoDB
Data analysis	Built-in data analysis capabilities (MapReduce)	Not supported	MongoDB is better than Redis
Application Scenarios	Increased access efficiency for massive data	Performance and operation of smaller data volumes	MongoDB is better than Redis

MongoDB and Redis differences