NodeUkraine - Postgresql для хипстеров или почему ваш следующий проект должен быть на PostgreSQL

PostgreSQL для хипстеров
или почему ваш следующий проект должен быть на PostgreSQL
https://goo.gl/1uAZNi

Кто использует PostgreSQL

• по привычке
• по предложению заказчика
• на хайпе
Как мы выбираем БД?

• по привычке
• по предложению заказчика
• на хайпе
• Исходя из требований
Как мы выбираем БД?

• 2003 — PG 8.2 - HSTORE
• 2012 — PG 9.2 - JSON
• 2013 — nested HSTORE (proposal) и
JSONB
• 2014 —PG 9.4 - JSONB, forget nested
hstore
• 2018? — SQL/JSON for 10.X or 11
JSON(B) в PostgreSQL

• select * from table where js->’field’ = 'foo' // field match
• where js @> '{"foo": "bar"}' // key-value match top-level
• where js ? 'b'// key exist
• {"a": 1} || {"b": 2} // {a: "1", b: "2"} - concat
• {a: "1", b: "2"} - "a" // {b: "2"} - delete key
JSON(B) в PostgreSQL

Найти "что-нибудь" красное
Table "public.js_test"
Column | Type | Modifiers
--------+---------+-----------
id | integer | not null
value | jsonb |
select * from js_test;
id |
----+-----------------------------------------------------------------------
1 | [1, "a", true, {"b": "c", "f": false}]
2 | {"a": "blue", "t": [{"color": "red", "width": 100}]}
3 | [{"color": "red", "width": 100}]
4 | {"color": "red", "width": 100}
5 | {"a": "blue", "t": [{"color": "red", "width": 100}], "color": "red"}
6 | {"a": "blue", "t": [{"color": "blue", "width": 100}], "color": "red"}
7 | {"a": "blue", "t": [{"color": "blue", "width": 100}], "colr": "red"}
8 | {"a": "blue", "t": [{"color": "green", "width": 100}]}
9 | {"color": "green", "value": "red", "width": 100}
(9 rows)

WITH RECURSIVE t(id, value) AS (
SELECT * FROM js_test
UNION ALL (
SELECT
t.id, 
COALESCE(kv.value, e.value) AS value
FROM t
LEFT JOIN LATERAL jsonb_each(
CASE WHEN jsonb_typeof(t.value) ='object'
THEN t.value ELSE NULL END
) kv ON true
LEFT JOIN LATERAL jsonb_array_elements(
CASE WHEN jsonb_typeof(t.value) = 'array'
THEN t.value ELSE NULL END 
) e ON true
WHERE
kv.value IS NOT NULL
OR e.value IS NOT NULL
)
)
SELECT js_test.* FROM (
SELECT id FROM t
WHERE
value @> '{"color":"red"}'
GROUP BY id 
) x
JOIN js_test ON js_test.id = x.id;
Найти "что-нибудь" красное

SELECT * FROM js_test
WHERE
value @@ '*.color = "red"';
JSQuery
https://github.com/postgrespro/jsquery

• Новый тип данных jsonpath
• Функции для конструирования JSON
• Функции для выполнения запросов к JSON-полям
SQL / JSON (SQL-2016)
SELECT * FROM js_test  
WHERE  
JSON_EXISTS(value, '$.**.color ? (@ == "red")');

JSON-агрегация
SELECT * FROM users  
LEFT JOIN comments ON comments.user_id = users.id
users.id users.name comments.id comments.text comments.user_id comments.created_at
1 alice 1 hello 1 31.12.2017 23:59:50
1 alice 2 Happy NY! 1 01.01.2018 00:00:10
2 bob 3 You too! 2 01.01.2018 00:00:50

select  
users.*, json_agg(comments.*) as comments 
from users
left join comments on comments.user_id = users.id
group by users.id
users.id users.name comments
1 alice [ 
{ id: 1, text: "hello", created_at: "31.12.2017 23:59:50" },  
{ id: 2, text: "Happy NY!", created_at: "01.01.2018 00:00:10"} 
]
2 bob [{ id: 3, text: "You too!", created_at: "01.01.2018 00:00:50"}]

select  
users.*, json_agg(comments.* ORDER BY created_at DESC) as comments 
from users
left join comments on comments.user_id = users.id
group by users.id
users.id users.name comments
1 alice [ 
{ id: 1, text: "hello", created_at: "31.12.2017 23:59:50" },  
{ id: 2, text: "Happy NY!", created_at: "01.01.2018 00:00:10"} 
]
2 bob [{ id: 3, text: "You too!", created_at: "01.01.2018 00:00:50"}]

Оконные функции
select * from events
id type source_id created_at
1 foo 1
2 bar 2
3 a 1
4 b 2
5 c 3
6 d 1
7 e 1
Последние два события по каждому source_id?

SELECT ROW_NUMBER() OVER (PARTITION by source_id) as row_number, * from events
row_number id type source_id created_at
1 7 e 1
2 6 d 1
3 3 a 1
4 1 foo 1
1 4 b 2
2 2 bar 2
1 5 c 3
Последние два события по каждому source_id?

WITH events_cte AS (
SELECT
row_number() OVER (PARTITION by source_id) AS row_number, *
FROM events
) SELECT * FROM events_cte WHERE row_number <= 2
row_nunmber id type source_id created_at
1 7 e 1
2 6 d 1
1 4 b 2
2 2 bar 2
1 5 c 3

• Все агрегирующие функции
• row_number, rank, dense_rank, percent_rank, cum_dist
• ntile(n)
• lag(value), lead(value)
• first_value, last_value, nth_value

• Много процессов
• Много серверов
Advisory locking

Advisory locking
1.Start transaction
2.pg_try_advisory_lock?
3.if success - start_operation()
4.else abort transaction
5.commit transaction -> release lock
1. Start transaction
2. pg_try_advisory_lock?
3. if success - start_operation()
4. else abort transaction
5. commit transaction -> release lock
process 1 process n…

Foreign Data Wrappers
• csv
• json
• mysql / postgres / oracle
• mongo
• elastic
• rest api
• whatever *

Foreign Data Wrappers
• MongoDB 3.2 now powered by PostgreSQL
• https://www.linkedin.com/pulse/mongodb-32-now-powered-
postgresql-john-de-goes/

Last but not least
• materialized view
• full text search
• pl/v8
• listen / notify
• native partitioning
• PostGIS
• where created_at <= NOW() - interval '5 weeks 2 hours 12
minutes'
• RDS / Aurora

node_modules
• MassiveJS - https://github.com/dmfay/massive-js
• MQL - https://github.com/marpple/MQL 
 
const posts = await QUERY `SELECT * FROM posts WHERE id = ${id}`
• Postgraphile - https://www.graphile.org/postgraphile/

Links
• https://postgresweekly.com
• https://dbweekly.com
• https://github.com/dhamaniasad/awesome-postgres
• https://nodeweekly.com

Статистика переходов

Вопросы?
Спасибо!

NodeUkraine - Postgresql для хипстеров или почему ваш следующий проект должен быть на PostgreSQL

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