8. What is redis ?
REmote DIctionary Server
Open-source, in-memory, persistable
key-value advanced datastore
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9. It’s an Open source project
✘Created in 2009
✘ by @antirez
(Salvatore Sanfilippo)
✘https://github.com/antirez
/redis
✘http://redis.io/
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10. The redis manifesto
We’re against complexity
the best way to fight complexity
Is, by not creating it at all.
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11. is used in
Computer
Science to
describe the
performance of
an algorithm
Big O notation O(n)
describes the
worst case
scenario, used to
describe the
execution time
required 11
15. What is a key-value store
CREATE TABLE redis (
k VARCHAR(512MB) NOT NULL,
v VARCHAR(512MB),
PRIMARY KEY (k)
);
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16. Data Structure: strings
used to store 3 types of values:
■ Byte string values
■ Integer values
■ Floating-point values
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17. SET & GET
SET tag ’#jab16’
GET tag
String operations
INSERT & SELECT
INSERT INTO redis
(k,v) VALUES
(‘tag’,’#jab16’)
SELECT v FROM redis
WHERE k=‘tag’
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29. Data structure:Lists
✘Is a sequence of ordered strings
✘Up to 2^32 (4 billion) of elements
✘Duplicate possible
✘O(N) - more fast (head/tail)
✘LPUSH mylist “A”
✘RPUSH mylist “Z”
✘RPOP mylist
✘LPOP mylist
✘LINDEX mylist 3
✘LRANGE mylist 4 10
✘LTRIM mylist 0 4
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30. LISTS: USE CASE
✘Social network Timeline
✘last user activities, Top n viewed
✘Queques / Stack (LIFO-FIFO)
✘Producer – Consumer
✘Asynchronous job
✘Capped list
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31. Data structure:Sets
✘Sets are an unordered collection of
String, similar to Lists but no duplicates
allowed
✘Up to 2^32 (4 billion) of elements
✘SADD myset “G” “A” “N”
✘SCARD myset
✘SISMEMBER myset “C”
✘SREM myset “Z”
✘SUNION
✘SINTER (Algebra of sets)
✘SDIFF
myset
A
B
Z
D
G
N
J
B
Z
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32. Sets use case:Relationships
SADD user:1:friends 3 4 5 /* add some friends of user:1 */
SCARD user:1:friends /* How many friends does user:1 have? */
SINTER user:1:friends user:2:friends /* Common friends */
SDIFF user:1:friends user:2:friends /* Exclusive friends */
SUNION user:1:friends user:2:friends /* All the friends */
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33. Data structure: Sorted Sets
✘Like sets, sorted sets are composed of unique, string elements
✘every element in a ZSET have a floating point value called the score
✘elements in a sorted sets are taken in order
✘Intersection with ZINTERSTORE union ZUNIONSTORE
✘Uselful l to manage Leaderboard / scoreboard
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35. ABOUT REDIS KEYS
✘ Very long keys are not a good idea.
✘ Very short keys are often not a good idea.
✘ The maximum allowed key size is 512 MB.
✘ As a convention colon is used (user:1234:followers)
✘ Schema is your keys names so keep them in order.
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36. Key-point
✘ Limitation physical memory
✘ Survive crash disk persitence
✘ 160 commands
✘ Single threaded
✘ Replication master-slave
✘ Multilanguage support
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