> ## Documentation Index
> Fetch the complete documentation index at: https://docs.activeviam.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Parquet loading topic

> Configuration reference for `ParquetTopicDescription` properties such as `file-pattern`, `columns`, `source-store-mapping`, `channels`, and source restrictions, defined under the `dlc.parquet.topics` namespace.

### Configuration properties

Properties for a Parquet Loading Topic are defined by name in the `dlc.parquet.topics` namespace,
and are picked up as configurations for the DLC.

| Key                   | Required | Type                  | Default                                                                  | Description                                                                                                                                                                                                                                                                                                                |
| --------------------- | :------: | --------------------- | :----------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| file-pattern          |          | `String`              |                                                                          | Path matcher.                                                                                                                                                                                                                                                                                                              |
| columns               |          | `List<String>`        | Columns will implicitly come from the store which is being published to. | The order of columns in the file. If a column name matches a datastore column, its parser will be implied. For columns that do not match a datastore column, a parser must be provided in the channel as a [Custom Field](/configuration/custom-field). Columns without a matching datastore column or parser are skipped. |
| source-store-mapping  |          | `Map<String, String>` |                                                                          | Ordered map of fields in the record from the remote topic or queue.                                                                                                                                                                                                                                                        |
| channels              |          | `Set<Channel>`        | A channel is created using the topic's name as the name of the target.   | [Channels](/configuration/channel).                                                                                                                                                                                                                                                                                        |
| restrict-to-sources   |          | `Set<String>`         |                                                                          | Sources *to* which the topic is restricted. See [source to topic matching](/functional/source-to-topic-matching).                                                                                                                                                                                                          |
| restrict-from-sources |          | `Set<String>`         |                                                                          | Sources *from* which the topic is restricted. See [source to topic matching](/functional/source-to-topic-matching).                                                                                                                                                                                                        |

#### YAML example

This configuration does not specify a target for the data or the data format.

<Note>
  If the topic is not named the same as the store, the target must be explicitly specified in the [channel](/configuration/channel) of the topic.
</Note>

* The target is implicitly the Atoti table named "Trades".
* The format implicitly comes from the columns of the Atoti table.

```yaml theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
dlc:
  parquet:
    topics:
      Trades:
        file-pattern: glob:trades*.parquet
```

### Java configuration

`ParquetTopicDescription` Spring Beans are picked up as configurations for the DLC.

| Parameter           | Required | Type                      | Default                                                                  | Description                                                                                                                                                                                                                                                                                                                |
| ------------------- | :------: | ------------------------- | :----------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| name                |     Y    | `String`                  |                                                                          | Name of the topic.                                                                                                                                                                                                                                                                                                         |
| filePattern         |          | `String`                  |                                                                          | Path matcher.                                                                                                                                                                                                                                                                                                              |
| columns             |          | `List<String>`            | Columns will implicitly come from the store which is being published to. | The order of columns in the file. If a column name matches a datastore column, its parser will be implied. For columns that do not match a datastore column, a parser must be provided in the channel as a [Custom Field](/configuration/custom-field). Columns without a matching datastore column or parser are skipped. |
| sourceStoreMapping  |          | `Map<String, String>`     |                                                                          | Ordered map of fields in the record from the remote topic or queue.                                                                                                                                                                                                                                                        |
| channels            |          | `Set<ChannelDescription>` | A channel is created using the topic's name as the name of the target    | [Channel Descriptions](/configuration/channel) which belong to the topic.                                                                                                                                                                                                                                                  |
| restrictToSources   |          | `Set<String>`             |                                                                          | Sources *to* which the topic is restricted. See [source to topic matching](/functional/source-to-topic-matching).                                                                                                                                                                                                          |
| restrictFromSources |          | `Set<String>`             |                                                                          | Sources *from* which the topic is restricted. See [source to topic matching](/functional/source-to-topic-matching).                                                                                                                                                                                                        |

#### Java example

This configuration does not specify a target for the data or the data format.

<Note>
  If the topic is not named the same as the store, the target must be explicitly specified in the [channel](/configuration/channel) of the topic.
</Note>

* The target is implicitly the Atoti table named "Trades".
* The format implicitly comes from the columns of the Atoti table.

```java theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
@Bean
public ParquetTopicDescription tradesTopic() {
    return ParquetTopicDescription.builder("Trades", "glob:trades*.parquet")
            .build();
}
```