KALI ROHAN KOKA
AZEEM HIRANI
 A Simple database Implementing a Dictionary
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where keys are associated with values.
For e.g.: It can set the key “surname_1987” to the
string “Rohan”.
It is open sourced. First released in March 2009.
Redis takes entire dataset in memory. Dump of
dataset is created and loaded whenever server is
restarted.
Speed is the key feature. Estimated 80000+
operations per second at least
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Values can be associated with:
Strings – Binary safe so they can hold text,
images, compressed data, etc.
Lists – Lists of Strings for operations like
append, list length, range of elements,
sorting of lists
Sets – Addition and deletion of elements
from a set, Intersection, union, subtraction,
etc.
Zsets – Zadd, Zrange, Zscore, Zcard
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Some features like those of Memcached:
All data lives in the memory.
Faster, Light weight
Data exists in the memory
Support Multiple databases
Support for Integer counters
Atomic operations
 Memcached is not persistent.
 Memcached does not save as the purpose is to be used
only as a cache.
 Redis has capability of being used as main DB for the
application.
 Memcached uses key value model like Redis but keys
can be just string.
 In Redis, values can be Lists, Sets, Zsets.
 Strings- get, set, increment, decrement
 Lists- push, pop, length, range, trim
 Sets- add, remove, move, length, intersect, intersect
 Some more commands useful – save, lastsave (can be
used to force and verify disk persistance)
These type of commands operate on database. They do not
operate on individual keys.
 SELECT
 MOVE
 FLUSHALL
 SHUTDOWN
 SLAVEOF
 DBSIZE
 INFO
 MONITOR
 Pick your own Level.
 Redis supports Persistence
 Replication – Works as a master slave
 Publish/Subscribe
 Unreliable
 Indexes take a lot of RAM.