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tistaharahap / index-cardinality.sql
Last active August 27, 2016 11:47
MariaDB [fun]> SELECT COUNT(DISTINCT last_name) AS cardinality FROM users;
+-------------+
| cardinality |
+-------------+
| 9 |
+-------------+
@tistaharahap
tistaharahap / select-users.sql
Created August 27, 2016 11:33
MariaDB [fun]> SELECT * FROM users;
+----+------------+------------+
| id | first_name | last_name |
+----+------------+------------+
| 1 | Batista | Harahap |
| 2 | Rinto | Harahap |
| 3 | Michael | Jordan |
| 4 | Chris | Martin |
| 5 | Jordan | Sparks |
| 6 | Daniel | Craig |
@tistaharahap
tistaharahap / explain-index.sql
Created August 27, 2016 11:31
MariaDB [fun]> EXPLAIN SELECT * FROM users WHERE last_name = 'Harahap';
+------+-------------+-------+------+---------------+------------+---------+-------+------+-----------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-------+------+---------------+------------+---------+-------+------+-----------------------+
| 1 | SIMPLE | users | ref | last_names | last_names | 53 | const | 2 | Using index condition |
+------+-------------+-------+------+---------------+------------+---------+-------+------+-----------------------+
@tistaharahap
tistaharahap / create-index.sql
Created August 27, 2016 11:31
MariaDB [fun]> CREATE INDEX last_names ON users (last_name);
Query OK, 0 rows affected (0.05 sec)
Records: 0 Duplicates: 0 Warnings: 0
@tistaharahap
tistaharahap / select-where.txt
Created August 26, 2016 18:48
MariaDB [fun]> EXPLAIN SELECT * FROM users WHERE last_name = 'Harahap';
+------+-------------+-------+------+---------------+------+---------+------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-------+------+---------------+------+---------+------+------+-------------+
| 1 | SIMPLE | users | ALL | NULL | NULL | NULL | NULL | 10 | Using where |
+------+-------------+-------+------+---------------+------+---------+------+------+-------------+
1 row in set (0.00 sec)
@tistaharahap
tistaharahap / select-where.txt
Created August 26, 2016 18:47
MariaDB [fun]> SELECT * FROM users WHERE last_name = 'Harahap';
+----+------------+-----------+
| id | first_name | last_name |
+----+------------+-----------+
| 1 | Batista | Harahap |
| 2 | Rinto | Harahap |
+----+------------+-----------+
2 rows in set (0.00 sec)
@tistaharahap
tistaharahap / gist:c34cbdac3fb1f5187a9069e5167e7daf
Created August 26, 2016 18:44
MariaDB [fun]> EXPLAIN SELECT * FROM users;
+------+-------------+-------+------+---------------+------+---------+------+------+-------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-------+------+---------------+------+---------+------+------+-------+
| 1 | SIMPLE | users | ALL | NULL | NULL | NULL | NULL | 10 | |
+------+-------------+-------+------+---------------+------+---------+------+------+-------+
@tistaharahap
tistaharahap / gist:ba6b28bf9b391b6eaf453b7719df3a36
Created August 26, 2016 18:43
MariaDB [fun]> SELECT * FROM users;
+----+------------+------------+
| id | first_name | last_name |
+----+------------+------------+
| 1 | Batista | Harahap |
| 2 | Rinto | Harahap |
| 3 | Michael | Jordan |
| 4 | Chris | Martin |
| 5 | Jordan | Sparks |
| 6 | Daniel | Craig |
@tistaharahap
tistaharahap / select-names.sql
Created August 26, 2016 18:33
SELECT
first_name,
last_name
FROM
names
@tistaharahap
tistaharahap / select-users.sql
Created August 26, 2016 18:32
SELECT * FROM users