The `consumer` in the connector contains the subscription api.
#### Create Consumer
The syntax for creating a consumer is `consumer = Consumer(configs)`. For more subscription api parameters, please refer to [Data Subscription](../../../develop/tmq/).
The `subscribe` function is used to subscribe to a list of topics.
```python
consumer.subscribe(['topic1', 'topic2'])
```
#### Consume
The `poll` function is used to consume data in tmq. The parameter of the `poll` function is a value of type float representing the timeout in seconds. It returns a `Message` before timing out, or `None` on timing out. You have to handle error messages in response data.
```python
while True:
res = consumer.poll(1)
if not res:
continue
err = res.error()
if err is not None:
raise err
val = res.value()
for block in val:
print(block.fetchall())
```
#### assignment
The `assignment` function is used to get the assignment of the topic.
```python
assignments = consumer.assignment()
```
#### Seek
The `seek` function is used to reset the assignment of the topic.
In addition to native connections, the connector also supports subscriptions via websockets.
#### Create Consumer
The syntax for creating a consumer is "consumer = consumer = Consumer(conf=configs)". You need to specify that the `td.connect.websocket.scheme` parameter is set to "ws" in the configuration. For more subscription api parameters, please refer to [Data Subscription](../../../develop/tmq/#create-a-consumer).
The `subscribe` function is used to subscribe to a list of topics.
```python
consumer.subscribe(['topic1', 'topic2'])
```
#### Consume
The `poll` function is used to consume data in tmq. The parameter of the `poll` function is a value of type float representing the timeout in seconds. It returns a `Message` before timing out, or `None` on timing out. You have to handle error messages in response data.
```python
while True:
res = consumer.poll(timeout=1.0)
if not res:
continue
err = res.error()
if err is not None:
raise err
for block in message:
for row in block:
print(row)
```
#### assignment
The `assignment` function is used to get the assignment of the topic.
```python
assignments = consumer.assignment()
```
#### Seek
The `seek` function is used to reset the assignment of the topic.
@@ -356,8 +358,10 @@ The following configuration items apply to TDengine Sink Connector and TDengine
3.`timestamp.initial`: Data synchronization start time. The format is 'yyyy-MM-dd HH:mm:ss'. If it is not set, the data importing to Kafka will be started from the first/oldest row in the database.
4.`poll.interval.ms`: The time interval for checking newly created tables or removed tables, default value is 1000.
5.`fetch.max.rows`: The maximum number of rows retrieved when retrieving the database, default is 100.
6.`query.interval.ms`: The time range of reading data from TDengine each time, its unit is millisecond. It should be adjusted according to the data flow in rate, the default value is 1000.
7.`topic.per.stable`: If it's set to true, it means one super table in TDengine corresponds to a topic in Kafka, the topic naming rule is `<topic.prefix>-<connection.database>-<stable.name>`; if it's set to false, it means the whole DB corresponds to a topic in Kafka, the topic naming rule is `<topic.prefix>-<connection.database>`.
6.`query.interval.ms`: The time range of reading data from TDengine each time, its unit is millisecond. It should be adjusted according to the data flow in rate, the default value is 0, this means to get all the data to the latest time.
7.`out.format`: Result output format. `line` indicates that the output format is InfluxDB line protocol format, `json` indicates that the output format is json. The default is line.
8.`topic.per.stable`: If it's set to true, it means one super table in TDengine corresponds to a topic in Kafka, the topic naming rule is `<topic.prefix>-<connection.database>-<stable.name>`; if it's set to false, it means the whole DB corresponds to a topic in Kafka, the topic naming rule is `<topic.prefix>-<connection.database>`.
9.`topic.ignore.db`: Whether the topic naming rule contains the database name: true indicates that the rule is `<topic.prefix>-<stable.name>`, false indicates that the rule is `<topic.prefix>-<connection.database>-<stable.name>`, and the default is false. Does not take effect when `topic.per.stable` is set to false.