The document provides an extensive overview of various PostgreSQL features including syntactic sugar, data types like serial, array, hstore, XML, and JSON, along with creation and manipulation examples. It covers concepts such as sequences, text search, hierarchical data types, and full-text search functionality. Additionally, it showcases how to structure complex data and perform operations with these data types effectively.

1. Syntactic sugar in PostgreSQL
by Anton Abramchenko

2. Serial Data Type & Sequence
-- Create autoincrement
CREATE SEQUENCE example_seq
START WITH 3
INCREMENT BY 3
MINVALUE 3
NO MAXVALUE;
-- After table creation, the sequence entity_id_seq will be created
CREATE TABLE entity (
id SERIAL PRIMARY KEY,
value VARCHAR(255)
);
-- Check available sequences
SELECT * FROM pg_statio_user_sequences;

3. Sequence Control
-- Set next increment as current and return it
SELECT nextval('entity_id_seq'); -- 1
SELECT nextval('entity_id_seq'); -- 2
SELECT nextval('entity_id_seq'); -- 3
INSERT INTO entity(value) VALUES ('some foo') RETURNING id; -- 4
-- Update sequence and return updated value;
SELECT nextval('entity_id_seq');
-- Get current value
SELECT currval('entity_id_seq');
-- Get last inserted value
SELECT lastval();
-- Update sequence value
SELECT setval('entity_id_seq', 99);

4. One Sequence for Two Tables
CREATE SEQUENCE multi_entity_seq;
CREATE TABLE multi_entity_a(
id INTEGER DEFAULT nextval('multi_entity_seq') PRIMARY KEY,
value VARCHAR(255)
);
CREATE TABLE multi_entity_b(
id INTEGER DEFAULT nextval('multi_entity_seq') PRIMARY KEY,
value VARCHAR(255)
);
INSERT INTO multi_entity_a (value) VALUES ('some value of ' || currval('multi_entity_seq'))
RETURNING id; -- 1
INSERT INTO multi_entity_a (value) VALUES ('some value of ' || currval('multi_entity_seq'))
RETURNING id; -- 2

5. Reset Sequence
-- Truncate operation does not update the sequence
TRUNCATE TABLE entity;
-- Reset sequence
TRUNCATE TABLE entity RESTART IDENTITY;
-- Alter reset sequence
ALTER SEQUENCE entity_id_seq RESTART;
-- or
SELECT setval('entity_id_seq', 1, false);

6. Array Data Type
CREATE TABLE book (
id SERIAL PRIMARY KEY,
title VARCHAR(255) NOT NULL,
tags VARCHAR(255) [],
authors INT []
);
INSERT INTO book (title, tags, authors)
VALUES ( 'PostgreSQL 9.6 High Performance', '{PostgreSQL,9.6,High,Performance}', '{1, 2}'),
( 'Mastering PostgreSQL 9.6', '{PostgreSQL,9.6,Mastering}', '{10,12,3}'),
('PostgreSQL Administration Cookbook', 'Some info', '{9.5,Administration}', '{29,41,36}'),
( 'PostgreSQL High Performance Cookbook', '{PostgreSQL,High,Performance}','{18,35}');

7. Array Functions and Operands
-- in array
SELECT * FROM book WHERE '9.6' = ANY (tags);
-- not in array
SELECT * FROM book WHERE id != ALL (SELECT eq FROM (VALUES (1), (2)) AS t(eq));
-- select all rows with ‘high’ or 9.5 version
SELECT * FROM book WHERE '{9.5,High}' && tags;
-- select all rows with ‘high’ and 9.6 version
SELECT * FROM book WHERE '{9.6,High}' <@ tags;
-- Get books where title is like one of array title values
SELECT * FROM book WHERE book.title ~~* ANY (ARRAY ['%Perfor%', '%Admin%']);
-- Array to string conversion
SELECT array_to_string(tags, ',') FROM book;
-- Array to json conversion
SELECT array_to_json(tags) FROM book;

8. Extension hStore
CREATE EXTENSION hstore;
CREATE TABLE product (
id SERIAL PRIMARY KEY,
title VARCHAR(255) NOT NULL,
description TEXT,
price DECIMAL(12, 2) NOT NULL,
attributes HSTORE,
created_at TIMESTAMP WITH TIME ZONE DEFAULT (CURRENT_TIMESTAMP AT TIME ZONE
'UTC'),
updated_at TIMESTAMP
);

9. Adding data to hStore
INSERT INTO product (title, description, price, attributes)
VALUES ('Product A', 'Description', 35.00, 'color => red, weight => 1000, sku => LPT123'),
('Product B', 'Description', 70.00, 'color => blue, weight => 2500, sku => LPT145'),
('Product C', 'Description', 100.00, 'color => withe, weight => 1500, sku => LPT245,
is_something => true'),
('Product D', 'Description', 85.00,
'color => withe, weight => 3500, sku => LPT125, is_something => false, hidden => true'),
('Product E', 'Description', 10.00, 'color => red, weight => 1500, sku => LPT37')
RETURNING *;

10. Retrieving data from hStore
SELECT
title,
price :: MONEY,
attributes -> 'color' AS color,
attributes -> 'weight' AS weight,
attributes -> 'sku' AS sku
FROM product
WHERE (attributes -> 'weight') :: INT > 1500
ORDER BY replace(attributes -> 'sku', 'LPT', ' ');

11. hStore Data Manipulation
-- hstore key exists
SELECT * FROM product WHERE attributes ? 'is_something';
-- hstore contains all specified keys
SELECT * FROM product WHERE attributes ?& string_to_array('is_something,hidden', ',');
-- hstore to data records
SELECT
id,
(each(attributes)).key AS attribute,
(each(attributes)).value AS value
FROM product;

12. Creating XML data
-- Books to xml
CREATE TABLE book_as_xml (
id SERIAL PRIMARY KEY,
content XML NOT NULL
);
-- Transform all books to xml
INSERT INTO book_as_xml (content)
SELECT xmlroot(
xmlelement(NAME book, xmlforest(id, title, authors, tags)),
VERSION '1.1',
STANDALONE YES
) FROM book
RETURNING content;

13. XML2 - Transform XML to Presentable view
CREATE EXTENSION xml2;
CREATE OR REPLACE FUNCTION xml_pretty(TEXT)
RETURNS XML AS $body$
SELECT xslt_process($1,
'<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:strip-space elements="*" />
<xsl:output method="xml" indent="yes" />
<xsl:template match="node() | @*">
<xsl:copy>
<xsl:apply-templates select="node() | @*" />
</xsl:copy>
</xsl:template>
</xsl:stylesheet>' :: TEXT) :: XML
$body$ LANGUAGE SQL IMMUTABLE STRICT;

14. XML Manipulation
-- Show pretty xml
SELECT xml_pretty(content) FROM book_as_xml;
-- Xpath
SELECT array_to_string(xpath('//title/text()', content), '; ') FROM book_as_xml;
-- Get all tags values
SELECT array_to_string(xpath('//tags/element/text()', content), '; ') FROM book_as_xml;
-- Return all table content as xml
SELECT xmlroot(
xmlelement(name body, table_to_xml('book', TRUE, TRUE, '')),
VERSION '1.1',
STANDALONE YES
) FROM book;

15. JSON & JSONB
CREATE TABLE entity_as_jsonb (
id SERIAL PRIMARY KEY,
content JSONB
);
INSERT INTO entity_as_jsonb (type, content)
SELECT json_build_object(
'title', title,
id', id,
'description', description,
'price', price :: MONEY,
'attributes', attributes
) FROM product RETURNING * ;

16. JSON Data Retrieving
SELECT
content ->> 'id' AS id, -- like text
content ->> 'title' AS title, -- like text
content -> 'attributes' AS attributes, -- like json
content #>> '{attributes,sku}' AS sky -- by path
FROM entity_as_json
WHERE type = 'product' AND content #>> '{attributes,sku}' LIKE '%45';
-- Aggregate all table data
SELECT json_agg(content) FROM entity_as_json;
-- Array to json conversion
SELECT array_to_json(tags) FROM book;

17. JSON Append Function
CREATE OR REPLACE FUNCTION json_append(data JSON, insert_data JSON)
RETURNS JSON
IMMUTABLE LANGUAGE SQL AS $$
SELECT ('{' || string_agg(to_json(key) || ':' || value, ',') || '}') :: JSON
FROM (
SELECT * FROM json_each(data)
UNION ALL
SELECT * FROM json_each(insert_data)
) t;
$$;

18. JSON Merge Function
CREATE OR REPLACE FUNCTION json_merge(data JSON, merge_data JSON)
RETURNS JSON
IMMUTABLE LANGUAGE SQL AS $$
SELECT ('{' || string_agg(to_json(key) || ':' || value, ',') || '}') :: JSON
FROM (
WITH to_merge AS (
SELECT * FROM json_each(merge_data)
)
SELECT * FROM json_each(data) WHERE key NOT IN (SELECT key FROM to_merge)
UNION ALL
SELECT * FROM to_merge
) t;
$$;

19. Check Constraint
CREATE TABLE web_user (
id SERIAL PRIMARY KEY,
username VARCHAR(255) UNIQUE NOT NULL CHECK (trim(username) <> ''),
email VARCHAR(255) UNIQUE NOT NULL CHECK (valid_email(email)),
password CHARACTER(40) NOT NULL CHECK (char_length(password) = 40),
created TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
updated TIMESTAMP
);
CREATE EXTENSION pgcrypto;
INSERT INTO web_user VALUES (
'2', 'foo', 'abramchenkoa@bar.com', ENCODE(DIGEST('test', 'sha1'), 'hex')
);

20. Domain and Citext Extension
CREATE EXTENSION citext;
-- Create data type like email RFC5322
CREATE DOMAIN email AS citext
CHECK ( value ~ '^[a-zA-Z0-9.!#$%&''*+/=?^_`{|}~-]' ||
'+@[a-zA-Z0-9](?:[a-zA-Z0-9-]' ||
'{0,61}[a-zA-Z0-9])?(?:.[a-zA-Z0-9]' ||
'(?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$'
);

21. Write functions on Perl, Python, JS, Ruby, PHP
CREATE EXTENSION plperlu;
CREATE FUNCTION valid_email(text)
RETURNS boolean
LANGUAGE plperlu
IMMUTABLE LEAKPROOF STRICT AS
$$
use Email::Valid;
my $email = shift;
Email::Valid->address($email) or die "Invalid email address: $emailn";
return 'true';
$$;

22. Full Text Search
-- Add a new column
ALTER TABLE book ADD COLUMN search_fields TSVECTOR;
-- Fill the column for searching
UPDATE book
SET search_fields = to_tsvector(
'english',
book.title || ' ' || array_to_string(book.tags, ' ')
);
-- Add index
CREATE INDEX textsearch_idx ON book USING GIN (search_fields);

23. Search Queries
-- Get current text search config
SELECT get_current_ts_config(); -- english
-- Show all available text search configs
SELECT * FROM pg_ts_config;
-- Search examples
SELECT * FROM book
WHERE search_fields @@ to_tsquery('high & postgre:* & 9.6');
SELECT * FROM book
WHERE search_fields @@ plainto_tsquery(get_current_ts_config(), 'postgresql performance')
;
-- Displays query matching, how title matches the query
SELECT id, title, ts_headline(title, q) FROM book, to_tsquery('postgre:* & performance') AS q
WHERE setweight(to_tsvector('english', title),'A')
|| setweight(to_tsvector('english', content), 'B') @@ q;

24. Search By Trigrams
-- Enable extension
CREATE EXTENSION pg_trgm;
-- Add index
CREATE INDEX trgm_idx ON book USING GIST (title gist_trgm_ops);
-- How similar are the arguments
SELECT title, similarity(title, 'Postgre') AS sml
FROM book WHERE title % 'Postgre'
ORDER BY sml DESC;
-- How similar are the first string and the most similar word of the second string
SELECT title, word_similarity(title, 'Postgre') AS sml
FROM book WHERE title %> 'Postgre'
ORDER BY sml DESC;

25. Ltree Hierarchical Data Type
-- Enable extension
CREATE EXTENSION ltree;
-- Store branch like
CREATE TABLE comment (
id SERIAL PRIMARY KEY,
message TEXT,
branch LTREE NOT NULL,
created TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
);
-- Add index
CREATE INDEX ON comment USING GIST (branch);

26. Ltree Data Manipulation
INSERT INTO comment (message, branch) VALUES ('Comment 1', '0');
INSERT INTO comment (message, branch) VALUES ('Comment 1.1', '0.1');
INSERT INTO comment (message, branch) VALUES ('Comment 2', '0');
INSERT INTO comment (message, branch) VALUES ('Comment 2.1', '0.3');
INSERT INTO comment (message, branch) VALUES ('Comment 2.2', '0.3');
INSERT INTO comment (message, branch) VALUES ('Comment 2.2.1', '0.3.4');
-- Сhildren of the third message
SELECT * FROM comment WHERE branch <@ '0.3';
-- Get by lquery
SELECT * FROM comment WHERE branch ~ '*.3.*'::lquery;

27. Thank You For Attention!