I don't have enough information about how source connector works in KSQLDb and Kafka altogether.
How much fast the data is populated to Kafka topics?
And what if KsqlDb stream needs data from source to join data, but data is loaded still?
Does source connector send updated/inserted data to topic, it happens instantly?
Could you help me with these issues or avice a good tutorial, where I can learn more.
- How much fast the data is populated to Kafka topics?
Depends on the connector. Some connectors are event driven and some use a polling mechanism. The event driven connectors are generally going to be more real-time, but often require more db-side setup. Where as the polling based connectors generally don't require any db-side changes. With the polling based connectors you can increase the polling frequency, trading lower latencies for high db load.
Look more into the documentation of the connectors for more info.
- And what if KsqlDb stream needs data from source to join data, but data is loaded still?
ksqlDB generally processes your data in time order. When joining two topics, ksqlDB will process the side with the oldest data. This will generally mean the stream data is not processed until the table is bootstrapped.
- Does source connector send updated/inserted data to topic, it happens instantly?
Not sure how this question differs from question #1.