mysql

Allows to perform SELECT queries on data that is stored on a remote MySQL server.

mysql('host:port', 'database', 'table', 'user', 'password'[, replace_query, 'on_duplicate_clause']);

Parameters

host:port — MySQL server address.
database — Remote database name.
table — Remote table name.
user — MySQL user.
password — User password.
replace_query — Flag that sets query substitution INSERT INTO to REPLACE INTO. If replace_query=1, the query is replaced.
on_duplicate_clause — The ON DUPLICATE KEY on_duplicate_clause expression that is added to the INSERT query.

Example: INSERT INTO t (c1,c2) VALUES ('a', 2) ON DUPLICATE KEY UPDATE c2 = c2 + 1, where on_duplicate_clause is UPDATE c2 = c2 + 1. See MySQL documentation to find which on_duplicate_clause you can use with ON DUPLICATE KEY clause.

To specify on_duplicate_clause you need to pass 0 to the replace_query parameter. If you simultaneously pass replace_query = 1 and on_duplicate_clause, ClickHouse generates an exception.

At this time, simple WHERE clauses and elements of AND chain in WHERE clause such as =, !=, >, >=, <, <=, LIKE, IN with compatible functions are also pushed down for execution on the MySQL server.

The rest of the conditions and the LIMIT constraint are executed in ClickHouse only after the query to MySQL finishes.

Returned Value

A table object with the same columns as the original MySQL table.

Usage Example

Table in MySQL:

mysql> CREATE TABLE `test`.`test` (
    ->   `int_id` INT NOT NULL AUTO_INCREMENT,
    ->   `int_nullable` INT NULL DEFAULT NULL,
    ->   `float` FLOAT NOT NULL,
    ->   `float_nullable` FLOAT NULL DEFAULT NULL,
    ->   PRIMARY KEY (`int_id`));
Query OK, 0 rows affected (0,09 sec)

mysql> insert into test (`int_id`, `float`) VALUES (1,2);
Query OK, 1 row affected (0,00 sec)

mysql> select * from test;
+--------+--------------+-------+----------------+
| int_id | int_nullable | float | float_nullable |
+--------+--------------+-------+----------------+
|      1 |         NULL |     2 |           NULL |
+--------+--------------+-------+----------------+
1 row in set (0,00 sec)

Selection of the data from ClickHouse:

SELECT * FROM mysql('localhost:3306', 'test', 'test', 'bayonet', '123')

┌─int_id─┬─int_nullable─┬─float─┬─float_nullable─┐
│      1 │         ᴺᵁᴸᴸ │     2 │           ᴺᵁᴸᴸ │
└────────┴──────────────┴───────┴────────────────┘

2.9 KiB Raw Blame History

mysql

Usage Example

See Also

2.9 KiB

Raw Blame History