Lesser-known Postgres features(hakibenita.com)

  id int SERIAL

  id int GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY

    SELECT *
    INTO TEMP copy
    FROM foobar;
    \copy "copy" to 'foobar.csv' with csv headers

    LISTEN new_data;
    SELECT ...;

    SELECT *
    FROM users
    WHERE email ~ ANY('{@gmail\.com$|@yahoo\.com$}')

    with connection.cursor() as cursor:
        cursor.execute('''
            SELECT *
            FROM users
            WHERE email ~ ANY(ARRAY%(patterns)s)
        ''' % {
            'patterns': [
                '@gmail\.com$',
                '@yahoo\.com$',
            ],
        })

  SELECT user_id, ARRAY_AGG(STRUCT(post_id, text, timestamp) ORDER BY timestamp DESC LIMIT 1)[SAFE_OFFSET(0)].*
  FROM posts
  GROUP BY user_id

  # create table users (id int primary key, email text);
  CREATE TABLE
  # create unique index on users(lower(email));
  CREATE INDEX
  # set enable_seqscan to false;
  SET
  
  # insert into users values (1, '[email protected]'), (2, '[email protected]'), (3, '[email protected]');
  INSERT 0 3
  # explain select * from users where email ~* '@(gmail.com|yahoo.com)$';
                                  QUERY PLAN
  --------------------------------------------------------------------------
   Seq Scan on users  (cost=10000000000.00..10000000025.88 rows=1 width=36)
     Filter: (email ~* '@(gmail.com|yahoo.com)$'::text)

  # create index on users(reverse(lower(email)) collate "C"); -- collate C explicitly to enable prefix lookups
  CREATE INDEX

  # explain select * from users where reverse(lower(email)) ~ '^(moc.liamg|moc.oohay)';
                                               QUERY PLAN
  ----------------------------------------------------------------------------------------------------
   Bitmap Heap Scan on users  (cost=4.21..13.71 rows=1 width=36)
     Filter: (reverse(lower(email)) ~ '^(moc.liamg|moc.oohay)'::text)
     ->  Bitmap Index Scan on users_reverse_idx  (cost=0.00..4.21 rows=6 width=0)
           Index Cond: ((reverse(lower(email)) >= 'm'::text) AND (reverse(lower(email)) < 'n'::text))