This document provides an overview of Redis data structures including strings, lists, sets, sorted sets, hashes, bit arrays, hyperloglogs, and streams. It discusses the basic commands to work with each data type as well as their time complexities. For example, it notes that lists allow fast insertion/removal from both ends and that sets do not allow duplicates. The document also covers database selection, scanning keys, and using bitfields to store compact data.

1. REDIS 101 - DATA STRUCTURE
ISMAIL ANJRINI - REDIS CERTIFIED DEVELOPER
08:00
PM
Wednesday 27 - Jan -
2021
ZOOM

2. ‫نعم‬
58
%
‫ال‬
42
%
‫استخدمت‬ ‫هل‬
Redis
‫مشروع؟‬ ‫في‬
‫نعم‬ ‫ال‬
95 of 296

3. KEYS

4. OVERVIEW
 Very long keys are not a good idea
 Use pattern for key names
 user:2435:settings
 The maximum allowed key size is 512 MB

5. KEYS PATTERN
 O(N) with N being the number of keys in the database
 Returns all keys matching pattern
 Redis running on an entry level laptop can scan a 1 million key database in 40 milliseconds
 Should only be used in production environments with extreme care

6. SCAN CURSOR [MATCH PATTERN] [COUNT COUNT] [TYPE TYPE]
 O(1) for every call.
 O(N) for a complete iteration
 N is the number of elements inside the collection
 SCAN is a cursor based iterator
 Returns only a small number of elements per call
 An iteration starts when the cursor is set to 0
 Terminates when the cursor returned by the server is 0

7. DEL - UNLINK
 DEL - O(N)
 UNLINK - O(1)

8. EXISTS KEY [KEY ...]
 O(1)
 EXISTS k1
 EXISTS k1 k2

9. TYPE KEY
 O(1)
 SET name ismail
 TYPE name -> string

10. FLUSHDB [ASYNC]
 O(N)
 Delete all the keys of the currently selected DB

11. DATABASE
S

12. Redis Cluster only supports database
zero
0 ->
15
Different databases can have keys with the same
name
SELECT
redis-cli -n
14

13. DATA TYPES

14. OVERVIEW
 Binary-safe strings.
 Lists
 Sets
 Sorted sets
 Hashes
 Bit arrays (or simply bitmaps)
 HyperLogLogs
 Streams

15. STRINGS

16. The Redis String type is the simplest type of value you can associate with a
Redis key
SET and the GET commands are the way we set and retrieve a string
value
A key value can't be bigger than 512
MB
GET “”
SET “” ismail
DEMO
Encoding is checked before command
execution

17. LIST

18. The speed of adding a new element to the head of a list with ten elements is the
same as adding an element to the head of list with 10 million elements
A List is just a sequence of
elements
value1 value2 value3 value4 value5
LPUS
H
RPOP
value1 value2 value3 value4 value5
LPUS
H
BRPOP
value1 value2
LPUS
H
value2
LMOVE
Duplicates are
allowed
Used to implement Stacks and
Queues

19. E1
E2 E1
E3 E2 E1
E4 E3 E2 E1
LPUS
H
RPOP
E4 E3 E2
E4 E3
E4
E1
E2 E1
E3 E2 E1
E4 E3 E2 E1
LPUS
H
LPOP
E3 E2 E1
E2 E1
E1

20. HASHES

21. Redis Hashes are maps between string fields and string
values
It is the perfect data type to represent
objects
A hash with a few fields is stored in a way that takes very little
space
id name age status level city
1981 Ismail 33 active 1 Riyadh
1985 Fadi 30 active 1 Aleppo
HSET user:1981 name Ismail age 33 status active level 1 city
Riyadh
HSET user:1985 name Fadi age 30 status active level 1 city
Aleppo

22. SETS

23. Sets are unordered collections of
strings
Intersection, union or difference between multiple
sets
Redis returns the elements in any order at every call from the same
set
Duplicates are NOT
allowed
SADD
SPOP
SMOV
E
SRANDMEMBER
SSCAN

24. SORTED SETS

25. Is similar to a mix between a Set and a
Hash
Every element in a sorted set is associated with a floating point value, called
the score
If A and B are two elements with a different score, then A > B if A.score is >
B.score
If A and B have exactly the same score, then A > B if the A string is lexicographically greater than the
B string
Duplicates are NOT
allowed
score name
99 ismail
101 riyadh
67 fadi
80 kasem

26. 0 0 0 0 0 0 0 0 0 0
Ismail Ahma
d
Fadi Riyad
h
Kasem Ave Sami John Emmy So
1)
"Ahmad"
2) "Ave"
3) "Emmy"
4) "Fadi"
5) "Ismail"
6) "John"
7) "Kasem"
8)
"Riyadh"
9) "Sami"
10) "So"
ZRANGEBYSCORE employees 0
+inf
ZRANGEBYLEX employees [A
[John
1) "Ahmad"
2) "Ave"
3) "Emmy"
4) "Fadi"
5) "Ismail"
6) "John"
ZRANGEBYLEX employees [A "[Axff"
1) "Ahmad"
2) "Ave"

27. BIT DATA

28. setbit page:about:2021:01 2
1
0010000
0
setbit page:about:2021:01 9
1
00100000
01000000
strlen page:about:2021:01 2
getbit page:about:2021:01 9 1
getbit page:about:2021:01
10
0
bitcount
page:about:2021:01
2
get
page:about:2021:01
" @"
BITOP AND
BITOP OR
BITOP XOR
BITOP NOT

29. BITFIELD i: Signed u:
Unsigned
0 3
u4
unsigne
d
4
bits
offset bitfield test set u4 0
2
0 0 1 0
bitfield test get u4 0
2
bitfield test get u4 2
8
1 0 0 0

30. 0 0 0 0 0 0 0 0 0 0
setbit visits:2020:12:05 9
1
0 0 0 0 0 0 0 0 0 1
setbit visits:2020:12:06 9
1
0 0 0 0 0 0 1 1 0 0
setbit visits:2020:12:10 9
1
1 0 1 0 0 1 1 0 1 1

31. BITOP OR visits:2020:12 visits:2020:12:05 visits:2020:12:06
visits:2020:12:10
1 0 1 0 0 1 1 1 0 1
BITOP AND visits:2020:12 visits:2020:12:05 visits:2020:12:06
visits:2020:12:10
0 0 0 0 0 0 0 0 0 0

32. 0 1 2
0
1
2
offset = Y * MAX_WIDTH + X

33. QUESTIONS

34. ‫في‬ ‫الصور‬ ‫حفظ‬ ‫الجيد‬ ‫من‬ ‫هل‬
Redis
‫؟‬
‫استخدام‬ ‫يمكن‬ ‫أين‬
Redis
‫؟‬

35. THANKS