> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-mintlify-8c05c8a2.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# PostgreSQL dictionary source

> Configure PostgreSQL as a dictionary source in ClickHouse.

Example of settings:

<Tabs>
  <Tab title="DDL">
    ```sql theme={null}
    SOURCE(POSTGRESQL(
        port 5432
        host 'postgresql-hostname'
        user 'postgres_user'
        password 'postgres_password'
        db 'db_name'
        table 'table_name'
        replica(host 'example01-1' port 5432 priority 1)
        replica(host 'example01-2' port 5432 priority 2)
        where 'id=10'
        invalidate_query 'SQL_QUERY'
        query 'SELECT id, value_1, value_2 FROM db_name.table_name'
    ))
    ```
  </Tab>

  <Tab title="Configuration file">
    ```xml theme={null}
    <source>
      <postgresql>
          <host>postgresql-hostname</hoat>
          <port>5432</port>
          <user>clickhouse</user>
          <password>qwerty</password>
          <db>db_name</db>
          <table>table_name</table>
          <where>id=10</where>
          <invalidate_query>SQL_QUERY</invalidate_query>
          <query>SELECT id, value_1, value_2 FROM db_name.table_name</query>
      </postgresql>
    </source>
    ```
  </Tab>
</Tabs>

<br />

Setting fields:

| Setting                | Description                                                                                                                                                                 |
| ---------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `host`                 | The host on the PostgreSQL server. You can specify it for all replicas, or for each one individually (inside `<replica>`).                                                  |
| `port`                 | The port on the PostgreSQL server. You can specify it for all replicas, or for each one individually (inside `<replica>`).                                                  |
| `user`                 | Name of the PostgreSQL user. You can specify it for all replicas, or for each one individually (inside `<replica>`).                                                        |
| `password`             | Password of the PostgreSQL user. You can specify it for all replicas, or for each one individually (inside `<replica>`).                                                    |
| `replica`              | Section of replica configurations. There can be multiple sections.                                                                                                          |
| `replica/host`         | The PostgreSQL host.                                                                                                                                                        |
| `replica/port`         | The PostgreSQL port.                                                                                                                                                        |
| `replica/priority`     | The replica priority. When attempting to connect, ClickHouse traverses the replicas in order of priority. The lower the number, the higher the priority.                    |
| `db`                   | Name of the database.                                                                                                                                                       |
| `table`                | Name of the table.                                                                                                                                                          |
| `where`                | The selection criteria. The syntax for conditions is the same as for `WHERE` clause in PostgreSQL. For example, `id > 10 AND id < 20`. Optional.                            |
| `invalidate_query`     | Query for checking the dictionary status. Optional. Read more in the section [Refreshing dictionary data using LIFETIME](/reference/statements/create/dictionary/lifetime). |
| `background_reconnect` | Reconnect to replica in background if connection fails. Optional.                                                                                                           |
| `query`                | The custom query. Optional.                                                                                                                                                 |

<Note>
  The `table` or `where` fields cannot be used together with the `query` field. And either one of the `table` or `query` fields must be declared.
</Note>