Redis is an in-memory key-value store that can be used as a cache or database. It supports varied data structures like Strings, Lists, Sets, Hashes and Sorted Sets. While it stores data in memory for high speed, it can also optionally write data to disk for persistence. Redis is useful for caching, real-time analytics or any use case requiring fast access to structured data.

1. WebエンジニアのためのはじめてのredisWebエンジニアのためのはじめてのredis
@nasa9084@nasa9084

2. $ whoami$ whoami
Masahiro Kitamura
@nasa9084
VirtualTech Japan Inc.
KEYWORDS: emacs python golang(new!) whiske?y

3. redisredis

4. What is "redis"?What is "redis"?
remote dictionary server
Key-Value Store (KVS)
Varied Data Structure
in-memory
having persistence
easy and fast
compatible w/Python, Ruby, …
→web engineers should learn redis!

5. Key-value Store (KVS)Key-value Store (KVS)
dict(Python)
hash(Perl, Ruby)
map(C++, Java, Go)
namespaces

6. Comparison with RDBMSsComparison with RDBMSs
Function RDBMS Redis
using simply △ ◎
high speed processing △ ◎
horizontal distribution × ◎
high availability △ ◎
persistency ◎ ○
complex query ◎ ×
transaction ◎ △
consistency ◎ △

7. Comparison with memcachedComparison with memcached
memcached redis
good at Cache Cache
data structure only string varied structure
persistency × ○
Disk I/O NOT DO can be disable
speed high high
multi thread ○ ×
memory efficiency △ ○

8. Redis Data StructureRedis Data Structure

9. StringString
String
replace
get length
number
INCR / DECR
max: 512MB
binary safe
can insert pictures, etc

10. StringString
redis python
> SET hoge fugafuga
OK
> GET hoge
"fugafuga"
> SET point 10
OK
> GET point
"10"
> INCR point
(integer) 11
> GET point
"11"
from redis import Redis
redis = Redis()
redis.set('hoge', 'fugafuga')
print(redis.get('hoge'))
#=> b'fugafuga'
redis.set('point', 10)
print(redis.get('point'))
#=> b'10'
redis.incr('point')
print(redis.get('point'))
#=> b'11'

11. ListList
List of Strings
Implemented with Linked List
insert or access to head or tail:
access to mid:
max size: 232-1 elements
O(1)
O(N)

12. ListList
redis python
> LPUSH 1 2 3
(integer) 3
> LRANGE piyo 0 -1
"3"
"2"
"1"
> LPOP piyo
"3"
> LRANGE piyo 0 -1
"2"
"1"
from redis import Redis
redis = Redis()
redis.lpush('piyo', 1, 2, 3)
print(redis.lrange('piyo', 0, -1))
#=> [b'3', b'2', b'1']
print(redis.lpop('piyo'))
#=> b'3'
print(redis.lrange('piyo', 0, -1))
#=> [b'2', b'1']

13. SetSet
Set of Strings
un-ordered
no duplication
add, delete, access avarage:
max size: 232-1 elements
O(1)

14. SetSet
redis python
> SADD foo 1 3 5
(integer) 3
> SMEMBERS foo
"1"
"3"
"5"
> SADD foo 1
(integer) 0
> SMEMBERS foo
"1"
"3"
"5"
from redis import Redis
redis = Redis()
redis.sadd('foo', 1, 3, 5)
print(redis.smembers('foo'))
#=>{b'3', b'5', b'1'}
redis.sadd('foo', 1)
print(redis.smembers('foo'))
#=>{b'3', b'5', b'1'}

15. Sorted Set (ZSet)Sorted Set (ZSet)
Set of Strings
no duplication
each members are ordered with its Score
take Score:
add:
O(1)
O(log N)

16. Sorted Set (ZSet)Sorted Set (ZSet)
redis python
> ZADD bar 20 ham
(integer) 1
> ZADD bar 10 egg
(integer) 1
> ZADD bar 30 spam
(integer) 1
> ZRANGE bar 0 -1 WITHSCORES
1) "egg"
2) "10"
3) "ham"
4) "20"
5) "spam"
6) "30"
from redis import Redis
redis = Redis()
redis.zadd('bar', 'ham', 20)
redis.zadd('bar', 'egg', 10)
redis.zadd('bar', 'spam', 30)
print(
redis.zrange('bar', 0, -1, withscores=True)
)
#=>[(b'egg', 10.0), (b'ham', 20.0), (b'spam', 30.0)]

17. HashHash
String to String map
Java: HashMap<String, String>
Go: ~map[string]string
add, delete, access:
max size: 232-1 pairs
O(1)

18. HashHash
redis python
> HSET bar 0:00 5
(integer) 1
> HGETALL bar
1) "0:00"
2) "5"
> HMSET bar 1:00 5 2:00 6
(integer) 2
> HKEYS bar
1) "0:00"
2) "1:00"
3) "2:00"
> HGET bar 0:00
"5"
from redis import Redis
redis = Redis()
redis.hset('bar', '0:00', '5')
print(redis.hgetall('bar'))
#=>{b'0:00': b'5'}
add_dict = {
'1:00': '5',
'2:00': '6'
}
redis.hmset('bar', add_dict)
print(redis.hkeys('bar'))
#=>[b'0:00', b'1:00', b'2:00]
print(redis.hget('bar', '0:00'))
#=>b'5'

19. UsecasesUsecases

20. data having expirationdata having expiration
can set expiration to key
EXPIRE key seconds
`key` is expired after `seconds` seconds
EXPIREAT key timestamp
`key` is expired on `timestamp`

21. for example,for example,
Session ID
One Time Token

22. Sample CodeSample Code
from redis import Redis
from uuid import uuid4
class User:
def generate_apikey(self):
redis = Redis(host='localhost', port=6389)
if redis.exists(self.token):
return self.token
new_apikey = 'hbt-' + str(uuid4())
ttl = 10 * 60 * 60 # 10 minutes
redis.setex(new_apikey, self.name, ttl)
self.apikey = new_apikey
return self.apikey
https://github.com/web-apps-tech/hubotmaker.git
https://hubot.web-apps.tech/

23. Real Time RankingReal Time Ranking
sorted set
zadd key score member
keyにscore点を持ったmemberを追加する add
a `member` that has `score` to `key`
zincrby key increment member
increment score of `member` of `key`
zrange key start stop
get `key`s members from `start` to `stop`

24. Sample CodeSample Code
from redis import Redis
redis = Redis()
while True:
print('input member:score> ', end='')
ipt = input()
if ipt == 'show': # command 'show'
ranking = redis.zrange('ranking', 0, 5, withscores=True)[::-1]
for i, m in enumerate(ranking):
values = {
'rank': i+1,
'member': m[0].decode(),
'point': m[1]
}
print('{rank}: {member} ({point}pt)'.format(**values))
continue
member, score = args.split(':')
redis.zadd('ranking', member, int(score))
print('good bye')
https://github.com/nasa9084/samples.git

25. try to use redistry to use redis

26. try redistry redis
http://try.redis.io/

27. official docker containerofficial docker container
$ docker run redis

28. in conclusionin conclusion
in-memory KVS
having persistency
very varied data structure
String, List, Set, Hash, SortedSet
you can try to use redis with `try redis`