JSON in Redis - When to use RedisJSON

1. PRESENTED
BY
JSON in Redis - When to use RedisJSON
Jay Won
Sr. Software Engineer, Coupang

2. PRESENTED
BY
1 Coupang <3 Redis
Why Coupang loves Redis and how we are using it.
2 RedisJSON
Redis module for JSON.
3 Benchmark Results
Comparing performance between String vs. Hash vs. RedisJSON.
Agenda:

3. PRESENTED
BY
Coupang

4. PRESENTED
BY
Coupang

5. PRESENTED
BY
Coupang

6. PRESENTED
BY
Coupang

7. PRESENTED
BY
Coupang

8. PRESENTED
BY
Coupang Ad Platform
Ad
Platform
1MM
RTT < 5ms
Limited Screen

9. PRESENTED
BY
Coupang Ad Platform <3 Redis
Ad
Platform
Limited Screen
1MM
RTT < 5ms

10. PRESENTED
BY
<customer_key> = {
"<ad_id>": {
"weekly": { // frequency type
"epoch": 1565025511888, // timestamp of first ad served
"cap": 7 // count of impressions
},
"daily": {
"epoch": 1565025511888,
"cap": 1
}
},
"<ad_id>": ...
}
<customer_key> = ...
Data Model: JSON

11. PRESENTED
BY
String vs. Hash commands for JSON
Type Commands
String 127.0.0.1:6379> GET customer24
(increment a single field)
127.0.0.1:6379> SET customer24 '{"ad1": {"daily": {"cap": 2020}}}'
Hash 127.0.0.1:6379> HGETALL customer24
(increment a single field)
127.0.0.1:6379> HSET customer24 ad1 '{"daily": {"cap": 2020}}'

12. PRESENTED
BY
RedisJSON
A Redis module that implements ECMA-404 The JSON
Data Interchange Standard as a native data type.

13. PRESENTED
BY
RedisJSON
127.0.0.1:6379> JSON.SET myjson . '{"redis": "rocks"}'
OK
127.0.0.1:6379> JSON.GET myjson .
"{"redis":"rocks"}"

14. PRESENTED
BY
RedisJSON
127.0.0.1:6379> JSON.SET myjson . '{"this": {"year": 2019}}'
OK
127.0.0.1:6379> JSON.GET myjson .this.year
"2019"
127.0.0.1:6379> JSON.NUMINCRBY myjson .this.year 1
"2020"

15. PRESENTED
BY
JSON in Redis
Type String Hash RedisJSON
Pros • Memory efficient
• Super fast in general
• Atomic field update
• Single key retrieval
(network efficient)
• Atomic field update
• Single key retrieval
(network efficient)
• Nested (full JSON support)
• Strongly typed
• Redis native
• No JSON <-> Hash convert
in client-side
Cons • Whole blob retrieval
(network is limited!)
• Non atomic JSON field
update
• Not nested (dictionary)
• JSON <-> Hash convert
in client-side
?????

16. PRESENTED
BY
Benchmark Topology

17. PRESENTED
BY
• YCSB vs. redis-benchmark
• Benchmarking latency is not always fair
– Network bandwidth
– Disk (AOF, RDB, …)
– Client-side configs like connection pool (threads), pipelining, etc.
Caveats

18. PRESENTED
BY
Benchmark Redis
Get a JSON object
1.003
44.703
414.719
0.979 5.279
133.247
0.977 4.991
16.559
0
100
200
300
400
500
5 fields 1K fields 10K fields
95th Percentile Latency in millisecond
JSON.GET {key} . HGETALL {key} GET {key}

19. PRESENTED
BY
Benchmark Redis
Update a single field of JSON
0.988
40.063
301.055
0.984 4.067 9.2470.984 5.075 9.423
0
100
200
300
400
500
5 fields 1K fields 10K fields
95th Percentile Latency in millisecond
JSON.NUMINCRBY {key} .{field1}.{field2} {value}
HSET {key} {field} {value}
SET {key} {value}

20. PRESENTED
BY
Benchmark Redis
RAM Usage
419%
398%
440%
158%
126%
148%
100% 100% 100%
0%
50%
100%
150%
200%
250%
300%
350%
400%
450%
500%
5 fields 1K fields 10K fields
used_memory_dataset
ReJSON Hash String

21. PRESENTED
BY
Why?
Path Evaluation: O(N*M)
JSON lexer: Additional RAM for Tree
Structure

22. PRESENTED
BY
• Go for RedisJSON if your {;} is small
– Know your workload
– Do benchmark
– Monitor Redis memory usage
Key Takeaways
When to use RedisJSON

23. PRESENTED
BY
• RedisJSON is getting improved
– RedisJSON2
– Secondary Index with RedisSearch
Key Takeaways

24. Thank You!