- Due to the recent research on big data conducted by laboratory of Computer Aidded Design and Computer Graphics, I made a brief summary over Redis here. Hope that will be helpful.
- Like Memcached, Redis is a kind of key-value database based on the memory. Support value types like:
- zset(sequencial set)
- Simple Installation()
- Redis has three main part , which are seperately memory storage, disk storage and Log file. There are three parameters corespondding to them are included in the configuration file:
save seconds updates, determines the frequency of updateoperation. It accepts more than one condition.
yes/no, means to start the log for Redis or not. Because synchronization is conducted by save, mentioned above, mass of data may get lost when the machine shutdown or power off, if there were no log to record that.
no/always/everysec, no denotes waiting for system I/O to write the data from memory to disk，
alwaysdenotes calling fsync() to update the data in disk after
everysecdenotes update every second.
- Redis doesn’t have much inside memery manage optimization, only having improvement on number type value：provide a number value pool from 1 to n for a better memory manage. Max value, n, can be set by modifying
- Redis vs. HBase over I/O：I/O of Redis is around 100,000 ops，delay from 10 to 70 milliseconds while local I/O of HBase is no more than 1,000ops/s，delay from 1 to 5 milliseconds.
- Redis vs. HBase on security：theoretically, HBase has something like Redo Log of Oracle(Write-ahead Log), therefore, data losing is hard to survive. Due to the outrageous price of data migration from memory to disk, the only way to implement data persistence is to make a data backup in the disk of slave machine. However, it is probable to get data lost when failover happens.