Sick and tired of "X technology is only good for starting out; after you do, move to Y"? Good news: you don't need to move away, you just need to get in further! In this talk, you'll learn about improvements in the newest version of the most used database in the world. What are Window Functions? How do you use CTEs? How can the new default encoding help me (emoji! 臘‍♀️)? We'll also talk about new JSON features and extended UUID support! Be prepared to drink from the firehose of what's new and awesome about MySQL 8.0.

1. OMG MySQL 8.0 is out! Are
we there yet?
Gabriela Ferrara
@gabidavila
http://gabriela.io | gabi.fyi/feedback

2. @gabidavila
Gabi
!
Developer Advocate

3. @gabidavila
Cloud SQL
PostgreSQLMySQL

4. @gabidavila
MySQL 8.0.12

5. @gabidavila
Are we there yet?
🤔
● Created to handle from up to
10 to 100M rows or around
100MB/table
● Now supports terabyte-sized
databases
● Supports parts of SQL
standards as new as SQL 2016
● But... some stuff from SQL
2003 just became available
(Window Functions, CTEs)
● What can we go from here?

6. @gabidavila
What Happened to 6.0 and 7.0?

7. @gabidavila
Topics
● New Defaults & Variables
● InnoDB Performance
● Window Functions
● CTE - Common Table Expressions

8. @gabidavila
New Defaults & Variables

9. @gabidavila
New default Charset
● Default:
● 5.7: latin1
● 8.0: utf8mb4
● Improvements:
● ➕ Mathematical Equations 𝑒=𝑚·𝑐²
● 😁 🙄 &
● & more SMP (Supplementary Multilingual Plane) Characters

10. @gabidavila
New default Collation
● utf8mb4_0900_ai_ci
● UTF-8 version 9.0 support
● Accent Insensitive
● Case Insensitive
● No more 🍣 = 🍺 bug
● Caused by utf8mb4_general_ci or utf8mb4_unicode_ci
More information on how collations behave here.

11. @gabidavila
Other defaults & variables
● Binary log (log_bin) is enabled by default
● SHA-2 for authentication
● Mandatory default value for TIMESTAMP NOT NULL
● New variable to dedicated servers (default OFF),
innodb_dedicated_server=ON , controls dynamically:
● innodb_buffer_pool_size
● innodb_log_file_size
● innodb_flush_method

12. @gabidavila
InnoDB Performance

13. @gabidavila
Transaction Scheduling
RDBMS usually works on a FIFO architecture
Transaction A
Transaction B
Transaction C
Start
End

14. @gabidavila
CATS
First database in the world to
implement

15. @gabidavila
Contention Aware Transaction Scheduling

16. @gabidavila
CATS vs FIFO | Transactions per Second (TPS)
0
5500
11000
16500
22000
32 64 128 256 512
FIFO CATS
DataextractedfromMySQLServerTeamwebsite.
Transactions per Second x # Clients
Higher is better

17. @gabidavila
CATS vs FIFO | Latency
0
45
90
135
180
32 64 128 256 512
FIFO CATS
DataextractedfromMySQLServerTeamwebsite.
Mean Latency x # Clients
Lower is better

18. @gabidavila
ALGORITHM=INSTANT
● If possible, the default is INSTANT, else it will be INPLACE
● Only metadata changed on the Data Dictionary
● Supported on:
● Change index
● Rename Table
● SET/DROP DEFAULT
● MODIFY COLUMN
● ADD/DROP Virtual Columns
● ADD COLUMN (non-generated)
🐞 Tiny bug if you are migrating from 8.0.11

19. @gabidavila
Indexes

20. @gabidavila
DESCRIBE `lines`;
type null extra
id int(11) NO AUTO_INCREMENT
number int(11) YES
timpestamp_in_ms timestamp YES
character_id int(11) NO
episode_id int(11) NO
location_id int(11) NO
character_line text YES
word_count int(11) YES

21. @gabidavila
Invisible Indexes
● Not used by the optimizer
● Visible by default, to create an invisible index:
ALTER TABLE lines
ADD INDEX ix_word_count (word_count) INVISIBLE;
ALTER TABLE lines ALTER INDEX ix_word_count INVISIBLE;
ALTER TABLE lines ALTER INDEX ix_word_count VISIBLE;
● Toggle visibility:

22. @gabidavila
Now imagine if an Eloquent migration…

23. @gabidavila
Could do…

24. @gabidavila
Laravel
Taylor will be waiting your pull request!

25. @gabidavila
Invisible Indexes
SELECT *
FROM lines
WHERE word_count > 25
ORDER BY word_count DESC;
Invisible
Query cost: 59175.37
Visible
Query cost: 2847.86

26. @gabidavila
Descending Indexes
Up to 5.7
● Syntax allowed ASC or DESC when defining an index
However...
An index_col_name specification can end with ASC or DESC. These keywords are
permitted for future extensions for specifying ascending or descending index value
storage. Currently, they are parsed but ignored; index values are always stored in
ascending order.

27. @gabidavila
MySQL 8.0 has it!!!

28. @gabidavila
Descending Indexes
● No longer ignored and forcibly created as ASC
ALTER TABLE lines
ADD INDEX ix_word_count (word_count DESC);

29. @gabidavila
Descending Indexes
Can be scanned as intended or backwards
SELECT *
FROM lines
WHERE word_count > 25
ORDER BY word_count DESC;
-- OR WITH THE SAME COST
SELECT *
FROM lines
WHERE word_count > 25
ORDER BY word_count;

30. @gabidavila
DEMO

31. @gabidavila
More cool features!

32. @gabidavila
Window Functions

33. @gabidavila
What they do?
● Allows to analyze the rows of a given result set
● Can behave like a GROUP BY without changing the result set
● Allows you to use a frame to "peek" OVER a PARTITION of a window

34. @gabidavila
Window Functions
● Examples:
● Enumerate rows - ROW_NUMBER()
● Show Aggregated sums - SUM()
● Rank results - RANK(), DENSE_RANK()
● Look at neighboring rows - LEAD(), LAG()

35. @gabidavila
DESCRIBE `episodes`;
CREATE TABLE `episodes` (
`id` int(11) NOT NULL,
`title` varchar(255),
`episode_date` date,
`season` int(11),
`number_in_season` int(11),
`number_in_series` int(11),
`million_viewers` decimal(10, 2),
`imdb_rating` decimal(10, 2),
`imdb_votes` decimal(10, 2),
`image_url` text,
`video_url` text,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

36. @gabidavila
SELECT … FROM `episodes` LIMIT 10;
+----+--------------+-----------------------------------+--------+------------------+-----------------+
| id | episode_date | title | season | number_in_season | million_viewers |
+----+--------------+-----------------------------------+--------+------------------+-----------------+
| 1 | 1989-12-17 | Simpsons Roasting on an Open Fire | 1 | 1 | 26.70 |
| 2 | 1990-01-14 | Bart the Genius | 1 | 2 | 24.50 |
| 3 | 1990-01-21 | Homer's Odyssey | 1 | 3 | 27.50 |
| 4 | 1990-01-28 | There's No Disgrace Like Home | 1 | 4 | 20.20 |
| 5 | 1990-02-04 | Bart the General | 1 | 5 | 27.10 |
| 6 | 1990-02-11 | Moaning Lisa | 1 | 6 | 27.40 |
| 7 | 1990-02-18 | The Call of the Simpsons | 1 | 7 | 27.60 |
| 8 | 1990-02-25 | The Telltale Head | 1 | 8 | 28.00 |
| 9 | 1990-03-18 | Life on the Fast Lane | 1 | 9 | 33.50 |
| 10 | 1990-03-25 | Homer's Night Out | 1 | 10 | 30.30 |
+----+--------------+-----------------------------------+--------+------------------+-----------------+
10 rows in set (0.00 sec)

37. @gabidavila
Previous and Next episodes | LAG and LEAD
SELECT
id,
title,
LAG(episode_date, 1) OVER (ORDER BY episode_date) AS previous_episode,
episode_date,
LEAD(episode_date, 1) OVER (ORDER BY episode_date) AS next_episode,
million_viewers
FROM episodes;

38. @gabidavila
SELECT … FROM `episodes` LIMIT 10;
+----+-----------------------------------+------------------+--------------+--------------+-----------------+
| id | title | previous_episode | episode_date | next_episode | million_viewers |
+----+-----------------------------------+------------------+--------------+--------------+-----------------+
| 1 | Simpsons Roasting on an Open Fire | NULL | 1989-12-17 | 1990-01-14 | 26.70 |
| 2 | Bart the Genius | 1989-12-17 | 1990-01-14 | 1990-01-21 | 24.50 |
| 3 | Homer's Odyssey | 1990-01-14 | 1990-01-21 | 1990-01-28 | 27.50 |
| 4 | There's No Disgrace Like Home | 1990-01-21 | 1990-01-28 | 1990-02-04 | 20.20 |
| 5 | Bart the General | 1990-01-28 | 1990-02-04 | 1990-02-11 | 27.10 |
| 6 | Moaning Lisa | 1990-02-04 | 1990-02-11 | 1990-02-18 | 27.40 |
| 7 | The Call of the Simpsons | 1990-02-11 | 1990-02-18 | 1990-02-25 | 27.60 |
| 8 | The Telltale Head | 1990-02-18 | 1990-02-25 | 1990-03-18 | 28.00 |
| 9 | Life on the Fast Lane | 1990-02-25 | 1990-03-18 | 1990-03-25 | 33.50 |
| 10 | Homer's Night Out | 1990-03-18 | 1990-03-25 | 1990-04-15 | 30.30 |
+----+-----------------------------------+------------------+--------------+--------------+-----------------+
10 rows in set (0.01 sec)

39. @gabidavila
Break down
LAG(episode_date, 1) OVER (ORDER BY episode_date)
windowfunction
column
# rows preceding

40. @gabidavila
Repetition?
SELECT
id,
title,
LAG(episode_date, 1) OVER (ORDER BY episode_date) AS previous_episode,
episode_date,
LEAD(episode_date, 1) OVER (ORDER BY episode_date) AS next_episode,
million_viewers
FROM episodes;

41. @gabidavila
SELECT
id,
title,
LAG(episode_date, 1) OVER (dates) AS previous_episode,
episode_date,
LEAD(episode_date, 1) OVER (dates) AS next_episode,
million_viewers
FROM episodes
WINDOW dates AS (ORDER BY episode_date);
Named Windows!

42. @gabidavila
DEMO
Rank episodes by million_viewers

43. @gabidavila
CTE
Common Table Expressions

44. @gabidavila
Common Table Expressions
● Similar to CREATE [TEMPORARY] TABLE
● Doesn’t need CREATE privilege
● Can reference other CTEs (if those are already defined)
● Can be recursive
● Easier to read

45. @gabidavila
Rank episodes by million_viewers
SELECT
id,
season,
number_in_season AS '# in season',
title,
episode_date,
million_viewers,
DENSE_RANK() OVER (season_viewers) AS episode_rank
FROM episodes
WINDOW season_viewers
AS (PARTITION BY season ORDER BY million_viewers DESC)

46. @gabidavila
DEMO
Filter ranked episodes

47. @gabidavila
Recursive CTE
● Useful with hierarchical data
● The Recipe is:
● Base query comes first
● Second query comes after a UNION statement
● And the stop condition should be on the recursive call

48. @gabidavila
Fibonacci
WITH RECURSIVE fibonacci(recursion_level, fibonacci_number, next_number)
AS (
# Base Case
SELECT 0 AS recursion_level,
0 AS fibonacci_number,
1 AS next_number
UNION ALL
# Recursion query
SELECT recursion_level + 1,
next_number,
fibonacci_number + next_number
FROM fibonacci
# Stopping condition
WHERE
recursion_level < 10
)
SELECT * FROM fibonacci;

49. @gabidavila
Fibonacci
WITH RECURSIVE fibonacci(recursion_level, fibonacci_number, next_number)
AS (
# Base Case
SELECT 0 AS recursion_level,
0 AS fibonacci_number,
1 AS next_number
UNION ALL
# Recursion query
SELECT recursion_level + 1,
next_number,
fibonacci_number + next_number
FROM fibonacci
# Stopping condition
WHERE
recursion_level < 10
)
SELECT * FROM fibonacci;

50. @gabidavila
Fibonacci
+-----------------+------------------+-------------+
| recursion_level | fibonacci_number | next_number |
+-----------------+------------------+-------------+
| 0 | 0 | 1 |
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 3 |
| 4 | 3 | 5 |
| 5 | 5 | 8 |
| 6 | 8 | 13 |
| 7 | 13 | 21 |
| 8 | 21 | 34 |
| 9 | 34 | 55 |
| 10 | 55 | 89 |
+-----------------+------------------+-------------+
11 rows in set (0.00 sec)
Base case
Recursive Query

51. @gabidavila
Other Bits

52. @gabidavila
Other MySQL 8.0 Bits
● Users now can have ROLES
● JSON partial update
● Better Geospatial support
● Better UUID support
● Use MySQL without SQL (through MySQL Shell or X-DevApi)

53. @gabidavila
Thank you!
Please give me feedback on my talk!
gabi.fyi/feedback