"MySQL Boosting - DB Best Practices & Optimization" by José Luis Martínez (aka Pplu) - CTO @ CAPSiDE

2. This is not a DB
optimization talk
It’s a talk about how doing things in a specific way leads to getting way
better results by default

3. “Preoptimization”
 Don’t denormalize by default
 Maintenance is King (by default)
 1 Thread Performance != Parallel
Performance
MyISAM vs InnoDB
Fast != Scalable

4. “Preoptimization”

5. I’ll just tune MySQL Parameters…
 Will get you out of SOME trouble
 But not a good “default” solution, specially if the
base is flawed
 Please do tune MySQLs defaults
 Not the theme for today 

7. Start with your Schema
 Your schema is probably the root cause of your
“My DB doesn’t scale” problems
 The solution is not “have a loose/no schema”
 How to fake a DB Design (Curtis Ovid Poe)
 https://www.youtube.com/watch?v=y1tcbhWLiUM

8. Data types: how (not) to bloat your DB
 Selecting data types with a bit of care is very
productive
 It makes more data fit in less space
 Optimizes use of InnoDB Buffer Pool, MyISAM Key
Buffer, Join Buffer, Sort Buffer, Smaller indexes

9. Your new best friend
 http://dev.mysql.com/doc/refman/5.6/en/storage-requirements.html
 http://dev.mysql.com/doc/refman/5.5/en/storage-requirements.html
 …

10. DataTypes: NULL vs NOT NULL
 I don’t care about the NULL debate
 Saves Space
 Gives the DB hints
 Use NULLs wisely

11. Data Types: Integers

12. DataTypes: Integers
INT(1) == INT(10) == 4 bytes
That’s it!

13. DataTypes: Integer family
TINYINT: 1 byte
SMALLINT: 2 bytes
MEDIUMINT: 3 bytes
INT
BIGINT:8 bytes
UNSIGNED: “double”
the range

14. INTS and surrogate keys
 It’s good to have a surrogate key
 Just unique index the unique column
 Why?
 InnoDB stores the PK on the leafs of all indexes
 Indexes bloat if they’re “big keys”

15. Id columns for your tables
 INT by default for “things that can get big”
 Smaller INTs for smaller sets
 Do you really need a BIGINT?
 The magnitude comparison trick:
 Epochs in Unix have 4 bytes
 The epoch has been counting since 1970. Will run out in 2038
 An INT can identify ONE THING HAPPENING EVERY SECOND for 68 YEARS!
 Do you STILL need a BIGINT?

16. DataTypes: Integer family
TINYINT: 1 byte
SMALLINT: 2 bytes
MEDIUMINT: 3 bytes
INT
BIGINT:8 bytes
UNSIGNED: “double”
the range

17. DataTypes: Integer family
TINYINT: 1 byte
SMALLINT: 2 bytes
MEDIUMINT: 3 bytes
INT
BIGINT:8 bytes
UNSIGNED: “double”
the range

18. Data Types: Texts

19. DataTypes: Texts
 Texts are strings of bytes with a charset and a collation
BINARY and VARBINARY
CHAR and VARCHAR

20. DataTypes: Texts
BINARY(10) == 10 bytes
CHAR(10) ==? 10 bytes

21. DataTypes: Texts
BINARY(10) == 10 bytes
CHAR(10) ==? 10 bytes
CHAR(10) latin1: 10 bytes
CHAR(19) utf-8: 30 bytes

22. DataTypes: Texts
BINARY(10) == 10 bytes
CHAR(10) ==? 10 bytes
CHAR(10) latin1: 10 bytes
CHAR(19) utf-8: 30 bytes
VARBINARY(10) == 1 to 11 bytes
VARCHAR(10) ==? 1 to 11 bytes

23. DataTypes: Texts
BINARY(10) == 10 bytes
CHAR(10) ==? 10 bytes
CHAR(10) latin1: 10 bytes
CHAR(10) utf-8: 30 bytes
VARBINARY(10) == 1 to 11 bytes
VARCHAR(10) ==? 1 to 11 bytes
VARCHAR(10) latin 1: 1 to 11 bytes
VARCHAR(10) utf-8: 1 to 31 bytes

24. So I’ll just go for VARCHAR(255) on all
text columns
 “After all… I’ll just consume the number of bytes + 1”

25. So I’ll just go for VARCHAR(255) on all
text columns
 “After all… I’ll just consume the number of bytes + 1”
 When we need a temporary table
 https://dev.mysql.com/doc/refman/5.6/en/memory-storage-engine.html
 “MEMORY tables use a fixed-length row-storage format. Variable-length types such
as VARCHAR are stored using a fixed length”

27. So I’ll just go for VARCHAR(255) on all
text columns
Congrats! All your VARCHAR(255) are now
CHAR(255) in memory
That’s 255 bytes latin-1. Or 765 bytes utf-8
O_o
Note: do the maths on VARCHAR(65535)

28. DataTypes: BLOBS
 TEXT == BLOB == problems
 TEXT = BLOB + charset + collation
 TEXT fields are not unlimited!
 TINYTEXT and TINYBLOB (up to 256 bytes == x chars)
 TEXT / BLOB (up to 65KB == x chars)
 MEDIUMBLOB / MEDIUMTEXT (up to 16MB == x chars)
 LONGTEXT / LONGBLOB (up to 2GB == x chars)

29. SELECT * IS YOUR FRIEND?
 IF a SELECT contains a BLOB/TEXT column
Temporary tables go DIRECTLY to DISK

31. SELECT * IS YOUR FRIEND?
 IF a SELECT contains a BLOB/TEXT column
Temporary tables go DIRECTLY to DISK
Note: “Big” columns belong on a filesystem or an object store

32. DataTypes: Small Sets
 ENUM
 One value out of the possibilities (‘big’, ‘small’)
 SET
 A set of possible values (‘pool’,’terrace’,’fence’)
 SETS are NOT good for finding stuff
 FIND_IN_SET is a function. No indexes 
 Default to a separate table + relation

33. DataTypes: Dates
 YEAR = 1 byte (range from 1901 to 2155)
 DATE = 3 bytes
 TIME = 3 bytes
 DATETIME = 8 bytes
 TIMESTAMP = 4 bytes
Timestamp is an epoch. Ideal for “things that
happen now” (sold time, renewal date, etc)

34. Masked Data

35. Masked Types
An IP Address
234.34.123.92
CHAR(15)? VARCHAR(15)?

36. Masked Types

37. INT

38. INSERT INTO table (col) VALUES (INET_ATON(’10.10.10.10’));
SELECT INET_NTOA(col) FROM table;

39. Masked Types
MD5("The quick brown fox jumps over the lazy cat")
 71bd588d5ad9b6abe87b831b45f8fa95
 CHAR(32)

40. BINARY(16)

41. Masked Types
 UUIDs
 HASH functions
 Network masks

42. Indexes for starters

43. Indexes for starters

44. Index the two sides of relations
PK

45. Index the two sides of relations
Index this guy too!

46. Index the two sides of relations
Index this guy too!
And this guy!

49. PK is (contract_id, customer_id)
(Implied uniqueness)
Index “both ways”:
(customer_id, contract_id)
InnoDB optimization: Don’t index the full (customer_id, contract_id). The
index ALREADY HAS customer_id in it’s leafs. So just index (customer_id)
N-M relation: Junction tables

51. Don’t operate on fields
 Because they can’t use indexes
 WHERE column = ‘x’
WHERE column > 2000
WHERE column LIKE ‘prefix%’
 WHERE column + 2000 > 2013
WHERE FIND_IN_SET(column)
WHERE CONCAT(f1,f2) = “xxxx.com”
WHERE YEAR(date) = 2015
WHERE column LIKE ‘%.com’

52. Polish your maths: Algebra
Doesn’t use index
WHERE column + 2000 > 2013
WHERE FIND_IN_SET(‘pool’,column)
WHERE CONCAT(f1,’.’,f2) =
“xxxx.com”
WHERE YEAR(date) = 2015
WHERE column LIKE ‘%.com’
Uses index
WHERE column > 13
?
WHERE f1 = ‘xxxx’ AND f2 = ‘com’
WHERE date BETWEEN ’01-01-2015’
and ’31-12-2015’
?

53. The old switcheroo…
Doesn’t use index
WHERE column + 2000 > 2013
WHERE FIND_IN_SET(‘pool’,column)
WHERE CONCAT(f1,’.’,f2) =
“xxxx.com”
WHERE YEAR(date) = 2015
WHERE column LIKE ‘%.com’
Uses index
WHERE has_pool = 1
WHERE column_rev LIKE ‘moc.%’

54. The old switcheroo…
Doesn’t use index
WHERE column + 2000 > 2013
WHERE FIND_IN_SET(‘pool’,column)
WHERE CONCAT(f1,’.’,f2) =
“xxxx.com”
WHERE YEAR(date) = 2015
WHERE column LIKE ‘%.com’
Uses index
WHERE has_pool = 1
UPDATE t SET has_pool =
FIND_IN_SET(‘pool’,column);
WHERE column_rev LIKE ‘moc.%’
UPDATE t SET
column_rev=REVERSE(column)

56. CAT IS HERE

57. Wrap up
Schema
Data Types
How to select them
Masked Types
Indexes
Relations
Using them

58. Wrap up
 Smaller is better
VS

60. cpsd.es/SRE-job-team