mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-11-20 14:42:02 +00:00
20 lines
1.1 KiB
Markdown
20 lines
1.1 KiB
Markdown
<a name="table_engines-mysql"></a>
|
|
|
|
# MySQL
|
|
|
|
The MySQL engine allows you to perform SELECT queries on data that is stored on a remote MySQL server.
|
|
|
|
The engine takes 5-7 parameters: the server address (host and port); the name of the database; the name of the table; the user's name; the user's password; whether to use replace query; the on duplcate clause. Example:
|
|
|
|
```text
|
|
MySQL('host:port', 'database', 'table', 'user', 'password'[, replace_query, 'on_duplicate_clause']);
|
|
```
|
|
|
|
At this time, simple WHERE clauses such as ```=, !=, >, >=, <, <=``` are executed on the MySQL server.
|
|
|
|
The rest of the conditions and the LIMIT sampling constraint are executed in ClickHouse only after the query to MySQL finishes.
|
|
|
|
If `replace_query` is specified to 1, then `INSERT INTO` query to this table would be transformed to `REPLACE INTO`.
|
|
If `on_duplicate_clause` is specified, eg `update impression = values(impression) + impression`, it would add `on_duplicate_clause` to the end of the MySQL insert sql.
|
|
Notice that only one of 'replace_query' and 'on_duplicate_clause' can be specified, or none of them.
|