Когда стоит дилемма, какое DBMS решение выбрать, то приходится принимать во внимание много факторов — latency, bandwidth, ACID-complience, наличие/отсутствие server-side-scripting, возможности репликации, удобство развертывания и администрирования, наличие известных багов или maintenance window и т.д. Я хочу рассказать лишь об одном из факторов, который имеет особенное значение на проектах с многомиллионными аудиториями — это Total Cost of Ownership или, по-простому, цена. Чем больше аудитория у проекта, тем больше эта аудитория создает нагрузку на базы данных, тем больше должно быть серверов с базами данных, тем больше финансовых затрат это требует. Можно экстенсивно наращивать количество серверов, но до определенного предела, когда становится понятным, что далее дешевле будет внедрить новое, более производительное решение, которое позволит радикально снизить цену и количество железа. Мой рассказ будет посвящен тому, как мы в Почте@Mail.Ru перешли на Tarantool, и как его использование сэкономило нам миллион долларов.

1. Как сэкономить
$1 000 000
на
базах данных
Денис Аникин,
ТехДир Почты/Облака
Mail.Ru

2. Why use a DBMS?

3. Why use a DBMS?
+ QUERIES
+ ACID
+ INDEXING
+ TABLES
+ DURABILITY
DatabaseDatabase FileFile

4. Heavy read workload
APPAPP
DBDB
APPAPP
APPAPP APPAPP

5. Overloaded

6. Solution: replication
APPAPP DB MasterDB Master
Update
DB SlaveDB Slave
Replication
Select
DB SlaveDB Slave
DB SlaveDB Slave
DB SlaveDB Slave
DB SlaveDB Slave

7. Heavy write workload
APPAPP
DBDB
APPAPP
APPAPP APPAPP

8. Replication does not scale
writes

9. Solution: sharding
DBDB DBDB DBDB
DBDB DBDB DBDB
DBDB DBDB DBDB
Replication
Sharding

10. Who is the next problem?
…

11. The boss

12. The boss

13. Technology

14. We are loosing money

15. Close down

16. What should we do?

17. Cache!
DBDB DBDB
DBDB DBDB
DBDB DBDB
CacheCache
AppApp
Good
latency

18. But …

19. Inconsistency
DBDB DBDB
DBDB DBDB
DBDB DBDB
CacheCache
AppApp

20. Inconsistency
Still have sharding
DBDB DBDB
DBDB DBDB
DBDB DBDB
CacheCache
AppApp

21. Inconsistency
Cache does not optimize updates out!
DBDB DBDB
DBDB DBDB
DBDB DBDB
CacheCache
AppApp

22. Inconsistency
AppApp
CacheCache DBDB
Cache rebooted
Data’s lost

23. Inconsistency
AppApp
CacheCacheDBDB
Cache rebooted
Data’s lost

24. Cache
- Inconsistency
- Still need sharding
- What else?

25. Cache is not a DB
FileFile

26. Inconsistency
WHAT
TO
DO?

27. Smart cache
DBDB DBDB
DBDB DBDB
DBDB DBDB
Smart
Cache
Smart
Cache
AppApp
Good
latency

28. AppApp
Smart
Cache
Smart
Cache DBDB
Cache rebooted
OK
Well it’s better

29. Well it’s better, but …

30. Still inconsistency
Cache rebooted
Data lost
AppApp
Smart
Cache
Smart
Cache DBDB

31. Still sharding
DBDB DBDB
DBDB DBDB
DBDB DBDB
Smart
Cache
Smart
Cache
AppApp

32. Remember, yourboss …

33. … doesn’t like sharding

34. … because it’s way too
expensive

35. Cache
- Inconsistency
- Still need sharding
- No databaseproperties
- What else?

36. Cold start

37. Cold start
DBDB DBDB
DBDB DBDB
DBDB DBDB
CacheCache
Cold
Start
Kills
The
Cache

38. Cold start
DBDB
DBDB
DBDB
CacheCache
DBDB
DBDB
DBDB
DBDB
DBDB
DBDB
Only to
warmup
cache
Only to
warmup
cache

39. Cache
- Inconsistency
- Still need sharding
- No databaseproperties
- Cold start

40. How to warm it up?

41. How to warm it up?

42. Persistent cache
DiskDiskMemoryMemory
Dump

43. Do you like it?

44. Persistent cache
DiskDiskMemoryMemory
Dump
- IOPS
- STALE DATA
+ FAST WARMUP

45. How to fix it?

46. Persistent cache
DiskDiskMemoryMemory
Log
+ IOPS
+ FRESH DATA
+ FAST WARMUP
- BIGGER SIZE
100Mb/sec

47. There’s still a problem

48. Persistent cache
DiskDiskMemoryMemory
Dump & Log
+ IOPS
+ FRESH DATA
+ FAST WARMUP
+ OPTIMAL SIZE

49. Solved!

50. Cache is warmed up

51. Cache

52. Cache

53. Why use a DBMS at all?

54. Why use a DBMS at all?
• Durability
• Replication

55. Why use a DBMS at all?
• Durability. Whatdoes aDB
store?
• Replication

56. Why use a DBMS at all?
• Durability. What doesaDB
store?Hot&Colddata
• Replication

57. Temperature of data
9.9Tb9.9Tb100Gb100Gb

58. Temperature of data
9.9Tb9.9Tb
100Gb100Gb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
Shard
Replicate

59. Why do we copy a DB?

60. Temperature of data
9.9Tb9.9Tb
100Gb100Gb
Shard
Replicate
100Gb100Gb
100Gb100Gb
100Gb100Gb
100Gb100Gb
100Gb100Gb
100Gb100Gb

61. The boss’s still angry

62. Ideas?

63. Why use a DBMS at all?
• Durability. What doesaDB
store?Well, cacheis also
durablenow
• Replication

64. An idea!
CACHE
IS THE
PRIMARY
DATA SOURCE

65. An idea!
CACHE
IS THE
PRIMARY
DATA SOURCE
With replication

66. An idea!
CACHE
IS THE
PRIMARY
DATA SOURCE
With replication
And with all otherDBfeatures

67. Cache

68. Cache

69. Cache is not a DB
FileFile

70. Cache can be a DB!

71. Cache
Can
Be
A
DATABASE

72. + CACHE
+ PERSISTENCE
+ ACID TRANSACTIONS
+ REPLICATION
+ STORED PROCEDURES
DatabaseDatabase

73. Tarantool – forhot data
+ CACHE
+ PERSISTENCE
+ ACID TRANSACTIONS
+ REPLICATION
+ STORED PROCEDURES(LUA)
DatabaseDatabase

74. Tarantool

75. We’ve done it!
9.9Tb9.9Tb
100Gb100Gb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
9.9Tb9.9Tb
Shard
Replicate

76. We’ve done it!
9.9Tb9.9Tb
100Gb100Gb
SQL DBMS
Tarantool

77. Look back
• Shard, replica, cache, smart cache
• Shard exists, replicaback,
• Persistent cache, replication, acid.
Now cacheisaDB
• 2 instances could be enough

78. Cache. Why not?
• Dependable, durable
• You’reon theroad to cache
• No ACID, no consistency, no
durability
• Leavecozy DB for cache
• Tarantool helps come over
• No magic, just anew tool

79. Tarantool in Mail.Ru

80. Mail.Ru Users’ Profiles
ProfilesProfiles MySQLMySQL
MySQLMySQL
MySQLMySQL
MySQLMySQL
MySQLMySQL
MySQLMySQL
16x1/8 of workload

81. Mail.Ru Users’ Profiles
$1.2M upfront
$300K each year
128x MySQL128x MySQL 4x Tarantool4x TarantoolVS
$20K upfront
$5K each year
60 times!!!
Saved more than $1 000 000

82. Mail.Ru Email &Cloud
$100M+
TarantoolTarantool120+ instances of

83. The bottom line is …

84. Right tool forthe job

85. Saved $1 000 000 on a
feature

86. Summary

87. Questions?
Денис Аникин,
техдир Почты/ОблакаMail.Ru
anikin@corp.mail.ru
Skype: danikin2
Whatsapp/Viber: +79165129650